SYNOPSIS

cc <source> -ljim

or

jimsh [<scriptfile>|-]
jimsh -e '<immediate-script>'
jimsh --version
jimsh --help

INTRODUCTION

Jim Tcl is a small footprint reimplementation of the Tcl scripting language. The core language engine is compatible with Tcl 8.5+, while implementing a significant subset of the Tcl 8.6 command set, plus additional features available only in Jim Tcl.

Some notable differences with Tcl 8.5/8.6 are:

  1. Object-based I/O (aio), but with a Tcl-compatibility layer

  2. I/O: Support for sockets and pipes including udp, unix domain sockets and IPv6

  3. Integers are 64bit

  4. Support for references (ref/getref/setref) and garbage collection

  5. Builtin dictionary type (dict) with some limitations compared to Tcl 8.6

  6. env command to access environment variables

  7. Operating system features: os.fork, os.uptime, wait, signal, alarm, sleep

  8. Much better error reporting. info stacktrace as a replacement for $errorInfo, $errorCode

  9. Support for "static" variables in procedures

  10. Threads and coroutines are not supported

  11. Command and variable traces are not supported

  12. Built-in command line editing

  13. Expression shorthand syntax: $(…)

  14. Modular build allows many features to be omitted or built as dynamic, loadable modules

  15. Highly suitable for use in an embedded environment

  16. Support for UDP, IPv6, Unix-Domain sockets in addition to TCP sockets

RECENT CHANGES

Changes between 0.78 and 0.79

  1. Add file mtimeus for high resolution file timestamps

  2. aio now supports datagram Unix-Domain sockets

  3. Add support for aio lock -wait

  4. Add signal block to prevent delivery of signals

  5. Add support for file split

  6. Add support for json::encode and json::decode

  7. aio tty now allows setting echo without full raw mode

Changes between 0.77 and 0.78

  1. Add serial/tty support with aio tty

  2. Add support for jimsh -

  3. Add hidden -commands option to many commands

  4. Add scriptable autocompletion support in interactive mode with tcl::autocomplete

  5. Add aio sockopt

  6. Add scriptable autocompletion support with history completion

  7. Add support for tree delete

  8. Add support for defer and $jim::defer

  9. Renamed os.wait to wait, now more Tcl-compatible and compatible with exec ... &

  10. pipe is now a synonym for socket pipe

  11. Closing a pipe open with open |... now returns Tcl-like status

  12. It is now possible to used exec redirection with a pipe opened with open |...

  13. Interactive line editing now supports multiline mode if $::history::multiline is set

Changes between 0.76 and 0.77

  1. Add support for aio sync

  2. Add SSL and TLS support in aio

  3. Added zlib

  4. Added support for boolean constants in expr

  5. string is now supports boolean class

  6. Add support for aio lock and aio unlock

  7. Add new interp command

Changes between 0.75 and 0.76

  1. glob now supports the -tails option

  2. Add support for string cat

  3. Allow info source to add source info

Changes between 0.74 and 0.75

  1. binary, pack and unpack now support floating point

  2. file copy -force handles source and target as the same file

  3. format now supports %b for binary conversion

  4. lsort now supports -unique and -real

  5. Add support for half-close with aio close ?r|w?

  6. Add socket pair for a bidirectional pipe

  7. Add --random-hash to randomise hash tables for greater security

  8. dict now supports for, values, incr, append, lappend, update, info and replace

  9. file stat no longer requires the variable name

  10. Add support for file link

TCL INTRODUCTION

Tcl stands for tool command language and is pronounced tickle. It is actually two things: a language and a library.

First, Tcl is a simple textual language, intended primarily for issuing commands to interactive programs such as text editors, debuggers, illustrators, and shells. It has a simple syntax and is also programmable, so Tcl users can write command procedures to provide more powerful commands than those in the built-in set.

Second, Tcl is a library package that can be embedded in application programs. The Tcl library consists of a parser for the Tcl language, routines to implement the Tcl built-in commands, and procedures that allow each application to extend Tcl with additional commands specific to that application. The application program generates Tcl commands and passes them to the Tcl parser for execution. Commands may be generated by reading characters from an input source, or by associating command strings with elements of the application’s user interface, such as menu entries, buttons, or keystrokes.

When the Tcl library receives commands it parses them into component fields and executes built-in commands directly. For commands implemented by the application, Tcl calls back to the application to execute the commands. In many cases commands will invoke recursive invocations of the Tcl interpreter by passing in additional strings to execute (procedures, looping commands, and conditional commands all work in this way).

An application program gains three advantages by using Tcl for its command language. First, Tcl provides a standard syntax: once users know Tcl, they will be able to issue commands easily to any Tcl-based application. Second, Tcl provides programmability. All a Tcl application needs to do is to implement a few application-specific low-level commands. Tcl provides many utility commands plus a general programming interface for building up complex command procedures. By using Tcl, applications need not re-implement these features.

Third, Tcl can be used as a common language for communicating between applications. Inter-application communication is not built into the Tcl core described here, but various add-on libraries, such as the Tk toolkit, allow applications to issue commands to each other. This makes it possible for applications to work together in much more powerful ways than was previously possible.

Fourth, Jim Tcl includes a command processor, jimsh, which can be used to run standalone Tcl scripts, or to run Tcl commands interactively.

This manual page focuses primarily on the Tcl language. It describes the language syntax and the built-in commands that will be available in any application based on Tcl. The individual library procedures are described in more detail in separate manual pages, one per procedure.

JIMSH COMMAND INTERPRETER

A simple, but powerful command processor, jimsh, is part of Jim Tcl. It may be invoked in interactive mode as:

jimsh

or to process the Tcl script in a file with:

jimsh filename

or to process the Tcl script from standard input:

jimsh -

It may also be invoked to execute an immediate script with:

jimsh -e "script"

Interactive Mode

Interactive mode reads Tcl commands from standard input, evaluates those commands and prints the results.

$ jimsh
Welcome to Jim version 0.73, Copyright (c) 2005-8 Salvatore Sanfilippo
. info version
0.73
. lsort [info commands p*]
package parray pid popen proc puts pwd
. foreach i {a b c} {
{> puts $i
{> }
a
b
c
. bad
invalid command name "bad"
[error] . exit
$

If jimsh is configured with line editing (it is by default) and a VT-100-compatible terminal is detected, Emacs-style line editing commands are available, including: arrow keys, ^W to erase a word, ^U to erase the line, ^R for reverse incremental search in history. Additionally, the h command may be used to display the command history.

Command line history is automatically saved and loaded from ~/.jim_history

In interactive mode, jimsh automatically runs the script ~/.jimrc at startup if it exists.

INTERPRETERS

The central data structure in Tcl is an interpreter (C type Jim_Interp). An interpreter consists of a set of command bindings, a set of variable values, and a few other miscellaneous pieces of state. Each Tcl command is interpreted in the context of a particular interpreter.

Some Tcl-based applications will maintain multiple interpreters simultaneously, each associated with a different widget or portion of the application. Interpreters are relatively lightweight structures. They can be created and deleted quickly, so application programmers should feel free to use multiple interpreters if that simplifies the application.

DATA TYPES

Tcl supports only one type of data: strings. All commands, all arguments to commands, all command results, and all variable values are strings.

Where commands require numeric arguments or return numeric results, the arguments and results are passed as strings. Many commands expect their string arguments to have certain formats, but this interpretation is up to the individual commands. For example, arguments often contain Tcl command strings, which may get executed as part of the commands. The easiest way to understand the Tcl interpreter is to remember that everything is just an operation on a string. In many cases Tcl constructs will look similar to more structured constructs from other languages. However, the Tcl constructs are not structured at all; they are just strings of characters, and this gives them a different behaviour than the structures they may look like.

Although the exact interpretation of a Tcl string depends on who is doing the interpretation, there are three common forms that strings take: commands, expressions, and lists. The major sections below discuss these three forms in more detail.

BASIC COMMAND SYNTAX

The Tcl language has syntactic similarities to both the Unix shells and Lisp. However, the interpretation of commands is different in Tcl than in either of those other two systems. A Tcl command string consists of one or more commands separated by newline characters or semi-colons. Each command consists of a collection of fields separated by white space (spaces or tabs). The first field must be the name of a command, and the additional fields, if any, are arguments that will be passed to that command. For example, the command:

    set a 22

has three fields: the first, set, is the name of a Tcl command, and the last two, a and 22, will be passed as arguments to the set command. The command name may refer either to a built-in Tcl command, an application-specific command bound in with the library procedure Jim_CreateCommand, or a command procedure defined with the proc built-in command.

Arguments are passed literally as text strings. Individual commands may interpret those strings in any fashion they wish. The set command, for example, will treat its first argument as the name of a variable and its second argument as a string value to assign to that variable. For other commands arguments may be interpreted as integers, lists, file names, or Tcl commands.

Command names should normally be typed completely (e.g. no abbreviations). However, if the Tcl interpreter cannot locate a command it invokes a special command named unknown which attempts to find or create the command.

For example, at many sites unknown will search through library directories for the desired command and create it as a Tcl procedure if it is found. The unknown command often provides automatic completion of abbreviated commands, but usually only for commands that were typed interactively.

It’s probably a bad idea to use abbreviations in command scripts and other forms that will be re-used over time: changes to the command set may cause abbreviations to become ambiguous, resulting in scripts that no longer work.

COMMENTS

If the first non-blank character in a command is #, then everything from the # up through the next newline character is treated as a comment and ignored. When comments are embedded inside nested commands (e.g. fields enclosed in braces) they must have properly-matched braces (this is necessary because when Tcl parses the top-level command it doesn’t yet know that the nested field will be used as a command so it cannot process the nested comment character as a comment).

GROUPING ARGUMENTS WITH DOUBLE-QUOTES

Normally each argument field ends at the next white space, but double-quotes may be used to create arguments with embedded space.

If an argument field begins with a double-quote, then the argument isn’t terminated by white space (including newlines) or a semi-colon (see below for information on semi-colons); instead it ends at the next double-quote character. The double-quotes are not included in the resulting argument. For example, the command

    set a "This is a single argument"

will pass two arguments to set: a and This is a single argument.

Within double-quotes, command substitutions, variable substitutions, and backslash substitutions still occur, as described below. If the first character of a command field is not a quote, then quotes receive no special interpretation in the parsing of that field.

GROUPING ARGUMENTS WITH BRACES

Curly braces may also be used for grouping arguments. They are similar to quotes except for two differences. First, they nest; this makes them easier to use for complicated arguments like nested Tcl command strings. Second, the substitutions described below for commands, variables, and backslashes do not occur in arguments enclosed in braces, so braces can be used to prevent substitutions where they are undesirable.

If an argument field begins with a left brace, then the argument ends at the matching right brace. Tcl will strip off the outermost layer of braces and pass the information between the braces to the command without any further modification. For example, in the command

    set a {xyz a {b c d}}

the set command will receive two arguments: a and xyz a {b c d}.

When braces or quotes are in effect, the matching brace or quote need not be on the same line as the starting quote or brace; in this case the newline will be included in the argument field along with any other characters up to the matching brace or quote. For example, the eval command takes one argument, which is a command string; eval invokes the Tcl interpreter to execute the command string. The command

    eval {
      set a 22
      set b 33
    }

will assign the value 22 to a and 33 to b.

If the first character of a command field is not a left brace, then neither left nor right braces in the field will be treated specially (except as part of variable substitution; see below).

COMMAND SUBSTITUTION WITH BRACKETS

If an open bracket occurs in a field of a command, then command substitution occurs (except for fields enclosed in braces). All of the text up to the matching close bracket is treated as a Tcl command and executed immediately. Then the result of that command is substituted for the bracketed text. For example, consider the command

    set a [set b]

When the set command has only a single argument, it is the name of a variable and set returns the contents of that variable. In this case, if variable b has the value foo, then the command above is equivalent to the command

    set a foo

Brackets can be used in more complex ways. For example, if the variable b has the value foo and the variable c has the value gorp, then the command

    set a xyz[set b].[set c]

is equivalent to the command

    set a xyzfoo.gorp

A bracketed command may contain multiple commands separated by newlines or semi-colons in the usual fashion. In this case the value of the last command is used for substitution. For example, the command

    set a x[set b 22
    expr $b+2]x

is equivalent to the command

    set a x24x

If a field is enclosed in braces then the brackets and the characters between them are not interpreted specially; they are passed through to the argument verbatim.

VARIABLE SUBSTITUTION WITH $

The dollar sign ($) may be used as a special shorthand form for substituting variable values. If $ appears in an argument that isn’t enclosed in braces then variable substitution will occur. The characters after the $, up to the first character that isn’t a number, letter, or underscore, are taken as a variable name and the string value of that variable is substituted for the name.

For example, if variable foo has the value test, then the command

    set a $foo.c

is equivalent to the command

    set a test.c

There are two special forms for variable substitution. If the next character after the name of the variable is an open parenthesis, then the variable is assumed to be an array name, and all of the characters between the open parenthesis and the next close parenthesis are taken as an index into the array. Command substitutions and variable substitutions are performed on the information between the parentheses before it is used as an index.

For example, if the variable x is an array with one element named first and value 87 and another element named 14 and value more, then the command

    set a xyz$x(first)zyx

is equivalent to the command

    set a xyz87zyx

If the variable index has the value 14, then the command

    set a xyz$x($index)zyx

is equivalent to the command

    set a xyzmorezyx

For more information on arrays, see VARIABLES - SCALARS AND ARRAYS below.

The second special form for variables occurs when the dollar sign is followed by an open curly brace. In this case the variable name consists of all the characters up to the next curly brace.

Array references are not possible in this form: the name between braces is assumed to refer to a scalar variable. For example, if variable foo has the value test, then the command

    set a abc${foo}bar

is equivalent to the command

    set a abctestbar

Variable substitution does not occur in arguments that are enclosed in braces: the dollar sign and variable name are passed through to the argument verbatim.

The dollar sign abbreviation is simply a shorthand form. $a is completely equivalent to [set a]; it is provided as a convenience to reduce typing.

SEPARATING COMMANDS WITH SEMI-COLONS

Normally, each command occupies one line (the command is terminated by a newline character). However, semi-colon (;) is treated as a command separator character; multiple commands may be placed on one line by separating them with a semi-colon. Semi-colons are not treated as command separators if they appear within curly braces or double-quotes.

BACKSLASH SUBSTITUTION

Backslashes may be used to insert non-printing characters into command fields and also to insert special characters like braces and brackets into fields without them being interpreted specially as described above.

The backslash sequences understood by the Tcl interpreter are listed below. In each case, the backslash sequence is replaced by the given character:

\b

Backspace (0x8)

\f

Form feed (0xc)

\n

Newline (0xa)

\r

Carriage-return (0xd).

\t

Tab (0x9).

\v

Vertical tab (0xb).

\{

Left brace ({).

\}

Right brace (}).

\[

Open bracket ([).

\]

Close bracket (]).

\$

Dollar sign ($).

\<space>

Space ( ): doesn’t terminate argument.

\;

Semi-colon: doesn’t terminate command.

\"

Double-quote.

\<newline>

Nothing: this joins two lines together into a single line. This backslash feature is unique in that it will be applied even when the sequence occurs within braces.

\\

Backslash (\).

\ddd

The digits ddd (one, two, or three of them) give the octal value of the character. Note that Jim supports null characters in strings.

\unnnn
\u{nnn}
\Unnnnnnnn

The UTF-8 encoding of the unicode codepoint represented by the hex digits, nnnn, is inserted. The u form allows for one to four hex digits. The U form allows for one to eight hex digits. The u{nnn} form allows for one to eight hex digits, but makes it easier to insert characters UTF-8 characters which are followed by a hex digit.

For example, in the command

    set a \{x\[\ yz\141

the second argument to set will be {x[ yza.

If a backslash is followed by something other than one of the options described above, then the backslash is transmitted to the argument field without any special processing, and the Tcl scanner continues normal processing with the next character. For example, in the command

    set \*a \\\{foo

The first argument to set will be \*a and the second argument will be \{foo.

If an argument is enclosed in braces, then backslash sequences inside the argument are parsed but no substitution occurs (except for backslash-newline): the backslash sequence is passed through to the argument as is, without making any special interpretation of the characters in the backslash sequence. In particular, backslashed braces are not counted in locating the matching right brace that terminates the argument. For example, in the command

    set a {\{abc}

the second argument to set will be \{abc.

This backslash mechanism is not sufficient to generate absolutely any argument structure; it only covers the most common cases. To produce particularly complicated arguments it is probably easiest to use the format command along with command substitution.

STRING AND LIST INDEX SPECIFICATIONS

Many string and list commands take one or more index parameters which specify a position in the string relative to the start or end of the string/list.

The index may be one of the following forms:

integer

A simple integer, where 0 refers to the first element of the string or list.

integer+integer or
integer-integer

The sum or difference of the two integers. e.g. 2+3 refers to the 5th element. This is useful when used with (e.g.) $i+1 rather than the more verbose [expr {$i+1}]

end

The last element of the string or list.

end-integer

The nth-from-last element of the string or list.

COMMAND SUMMARY

  1. A command is just a string.

  2. Within a string commands are separated by newlines or semi-colons (unless the newline or semi-colon is within braces or brackets or is backslashed).

  3. A command consists of fields. The first field is the name of the command. The other fields are strings that are passed to that command as arguments.

  4. Fields are normally separated by white space.

  5. Double-quotes allow white space and semi-colons to appear within a single argument. Command substitution, variable substitution, and backslash substitution still occur inside quotes.

  6. Braces defer interpretation of special characters. If a field begins with a left brace, then it consists of everything between the left brace and the matching right brace. The braces themselves are not included in the argument. No further processing is done on the information between the braces except that backslash-newline sequences are eliminated.

  7. If a field doesn’t begin with a brace then backslash, variable, and command substitution are done on the field. Only a single level of processing is done: the results of one substitution are not scanned again for further substitutions or any other special treatment. Substitution can occur on any field of a command, including the command name as well as the arguments.

  8. If the first non-blank character of a command is a #, everything from the # up through the next newline is treated as a comment and ignored.

EXPRESSIONS

The second major interpretation applied to strings in Tcl is as expressions. Several commands, such as expr, for, and if, treat one or more of their arguments as expressions and call the Tcl expression processors (Jim_ExprLong, Jim_ExprBoolean, etc.) to evaluate them.

The operators permitted in Tcl expressions are a subset of the operators permitted in C expressions, and they have the same meaning and precedence as the corresponding C operators. Expressions almost always yield numeric results (integer or floating-point values). For example, the expression

    8.2 + 6

evaluates to 14.2.

Tcl expressions differ from C expressions in the way that operands are specified, and in that Tcl expressions support non-numeric operands and string comparisons.

A Tcl expression consists of a combination of operands, operators, and parentheses.

White space may be used between the operands and operators and parentheses; it is ignored by the expression processor. Where possible, operands are interpreted as integer values.

Integer values may be specified in decimal (the normal case) or in hexadecimal (if the first two characters of the operand are 0x). Note that Jim Tcl does not treat numbers with leading zeros as octal.

If an operand does not have one of the integer formats given above, then it is treated as a floating-point number if that is possible. Floating-point numbers may be specified in any of the ways accepted by an ANSI-compliant C compiler (except that the f, F, l, and L suffixes will not be permitted in most installations). For example, all of the following are valid floating-point numbers: 2.1, 3., 6e4, 7.91e+16.

If no numeric interpretation is possible, then an operand is left as a string (and only a limited set of operators may be applied to it).

String constants representing boolean constants (0, 1, false, off, no, true, on, yes) are also recognized and can be used in logical operations.

  1. Operands may be specified in any of the following ways:

  2. As a numeric value, either integer or floating-point.

  3. As one of valid boolean constants

  4. As a Tcl variable, using standard $ notation. The variable’s value will be used as the operand.

  5. As a string enclosed in double-quotes. The expression parser will perform backslash, variable, and command substitutions on the information between the quotes, and use the resulting value as the operand

  6. As a string enclosed in braces. The characters between the open brace and matching close brace will be used as the operand without any substitutions.

  7. As a Tcl command enclosed in brackets. The command will be executed and its result will be used as the operand.

Where substitutions occur above (e.g. inside quoted strings), they are performed by the expression processor. However, an additional layer of substitution may already have been performed by the command parser before the expression processor was called.

As discussed below, it is usually best to enclose expressions in braces to prevent the command parser from performing substitutions on the contents.

For some examples of simple expressions, suppose the variable a has the value 3 and the variable b has the value 6. Then the expression on the left side of each of the lines below will evaluate to the value on the right side of the line:

    $a + 3.1                6.1
    2 + "$a.$b"             5.6
    4*[llength "6 2"]       8
    {word one} < "word $a"  0

The valid operators are listed below, grouped in decreasing order of precedence:

int() double() round() abs(), rand(), srand()

Unary functions (except rand() which takes no arguments)

  • int() converts the numeric argument to an integer by truncating down.

  • double() converts the numeric argument to floating point.

  • round() converts the numeric argument to the closest integer value.

  • abs() takes the absolute value of the numeric argument.

  • rand() returns a pseudo-random floating-point value in the range (0,1).

  • srand() takes an integer argument to (re)seed the random number generator. Returns the first random number from that seed.

sin() cos() tan() asin() acos() atan() sinh() cosh() tanh() ceil() floor() exp() log() log10() sqrt()

Unary math functions. If Jim is compiled with math support, these functions are available.

- + ~ !

Unary minus, unary plus, bit-wise NOT, logical NOT. None of these operands may be applied to string operands, and bit-wise NOT may be applied only to integers.

** pow(x,y)

Power. e.g. xy. If Jim is compiled with math support, supports doubles and integers. Otherwise supports integers only. (Note that the math-function form has the same highest precedence)

* / %

Multiply, divide, remainder. None of these operands may be applied to string operands, and remainder may be applied only to integers.

+ -

Add and subtract. Valid for any numeric operands.

<< >> <<< >>>

Left and right shift, left and right rotate. Valid for integer operands only.

< > <= >=

Boolean less, greater, less than or equal, and greater than or equal. Each operator produces 1 if the condition is true, 0 otherwise. These operators may be applied to strings as well as numeric operands, in which case string comparison is used.

== !=

Boolean equal and not equal. Each operator produces a zero/one result. Valid for all operand types. Note that values will be converted to integers if possible, then floating point types, and finally strings will be compared. It is recommended that eq and ne should be used for string comparison.

eq ne

String equal and not equal. Uses the string value directly without attempting to convert to a number first.

in ni

String in list and not in list. For in, result is 1 if the left operand (as a string) is contained in the right operand (as a list), or 0 otherwise. The result for {$a ni $list} is equivalent to {!($a in $list)}.

&

Bit-wise AND. Valid for integer operands only.

|

Bit-wise OR. Valid for integer operands only.

^

Bit-wise exclusive OR. Valid for integer operands only.

&&

Logical AND. Produces a 1 result if both operands are non-zero, 0 otherwise. Valid for numeric operands only (integers or floating-point).

||

Logical OR. Produces a 0 result if both operands are zero, 1 otherwise. Valid for numeric operands only (integers or floating-point).

x ? y : z

If-then-else, as in C. If x evaluates to non-zero, then the result is the value of y. Otherwise the result is the value of z. The x operand must have a numeric value, while y and z can be of any type.

See the C manual for more details on the results produced by each operator. All of the binary operators group left-to-right within the same precedence level. For example, the expression

    4*2 < 7

evaluates to 0.

The &&, ||, and ?: operators have lazy evaluation, just as in C, which means that operands are not evaluated if they are not needed to determine the outcome. For example, in

    $v ? [a] : [b]

only one of [a] or [b] will actually be evaluated, depending on the value of $v.

All internal computations involving integers are done with the C type long long if available, or long otherwise, and all internal computations involving floating-point are done with the C type double.

When converting a string to floating-point, exponent overflow is detected and results in a Tcl error. For conversion to integer from string, detection of overflow depends on the behaviour of some routines in the local C library, so it should be regarded as unreliable. In any case, overflow and underflow are generally not detected reliably for intermediate results.

Conversion among internal representations for integer, floating-point, string operands is done automatically as needed. For arithmetic computations, integers are used until some floating-point number is introduced, after which floating-point is used. For example,

    5 / 4

yields the result 1, while

    5 / 4.0
    5 / ( [string length "abcd"] + 0.0 )

both yield the result 1.25.

String values may be used as operands of the comparison operators, although the expression evaluator tries to do comparisons as integer or floating-point when it can. If one of the operands of a comparison is a string and the other has a numeric value, the numeric operand is converted back to a string using the C sprintf format specifier %d for integers and %g for floating-point values. For example, the expressions

    "0x03" > "2"
    "0y" < "0x12"

both evaluate to 1. The first comparison is done using integer comparison, and the second is done using string comparison after the second operand is converted to the string 18.

In general it is safest to enclose an expression in braces when entering it in a command: otherwise, if the expression contains any white space then the Tcl interpreter will split it among several arguments. For example, the command

    expr $a + $b

results in three arguments being passed to expr: $a, +, and $b. In addition, if the expression isn’t in braces then the Tcl interpreter will perform variable and command substitution immediately (it will happen in the command parser rather than in the expression parser). In many cases the expression is being passed to a command that will evaluate the expression later (or even many times if, for example, the expression is to be used to decide when to exit a loop). Usually the desired goal is to re-do the variable or command substitutions each time the expression is evaluated, rather than once and for all at the beginning. For example, the command

    for {set i 1} $i<=10 {incr i} {...}        ** WRONG **

is probably intended to iterate over all values of i from 1 to 10. After each iteration of the body of the loop, for will pass its second argument to the expression evaluator to see whether or not to continue processing. Unfortunately, in this case the value of i in the second argument will be substituted once and for all when the for command is parsed. If i was 0 before the for command was invoked then the second argument of for will be 0<=10 which will always evaluate to 1, even though i eventually becomes greater than 10. In the above case the loop will never terminate. Instead, the expression should be placed in braces:

    for {set i 1} {$i<=10} {incr i} {...}      ** RIGHT **

This causes the substitution of i to be delayed; it will be re-done each time the expression is evaluated, which is the desired result.

LISTS

The third major way that strings are interpreted in Tcl is as lists. A list is just a string with a list-like structure consisting of fields separated by white space. For example, the string

    Al Sue Anne John

is a list with four elements or fields. Lists have the same basic structure as command strings, except that a newline character in a list is treated as a field separator just like space or tab. Conventions for braces and quotes and backslashes are the same for lists as for commands. For example, the string

    a b\ c {d e {f g h}}

is a list with three elements: a, b c, and d e {f g h}.

Whenever an element is extracted from a list, the same rules about braces and quotes and backslashes are applied as for commands. Thus in the example above when the third element is extracted from the list, the result is

    d e {f g h}

(when the field was extracted, all that happened was to strip off the outermost layer of braces). Command substitution and variable substitution are never made on a list (at least, not by the list-processing commands; the list can always be passed to the Tcl interpreter for evaluation).

The Tcl commands concat, foreach, lappend, lindex, linsert, list, llength, lrange, lreplace, lsearch, and lsort allow you to build lists, extract elements from them, search them, and perform other list-related functions.

Advanced list commands include lrepeat, lreverse, lmap, lassign, lset.

LIST EXPANSION

A new addition to Tcl 8.5 is the ability to expand a list into separate arguments. Support for this feature is also available in Jim.

Consider the following attempt to exec a list:

    set cmd {ls -l}
    exec $cmd

This will attempt to exec a command named "ls -l", which will clearly not work. Typically eval and concat are required to solve this problem, however it can be solved much more easily with {*}.

    exec {*}$cmd

This will expand the following argument into individual elements and then evaluate the resulting command.

Note that the official Tcl syntax is {*}, however {expand} is retained for backward compatibility with experimental versions of this feature.

REGULAR EXPRESSIONS

Tcl provides two commands that support string matching using regular expressions, regexp and regsub, as well as switch -regexp and lsearch -regexp.

Regular expressions may be implemented one of two ways. Either using the system’s C library POSIX regular expression support, or using the built-in regular expression engine. The differences between these are described below.

NOTE Tcl 7.x and 8.x use perl-style Advanced Regular Expressions (ARE).

POSIX Regular Expressions

If the system supports POSIX regular expressions, and UTF-8 support is not enabled, this support will be used by default. The type of regular expressions supported are Extended Regular Expressions (ERE) rather than Basic Regular Expressions (BRE). See REG_EXTENDED in the documentation.

Using the system-supported POSIX regular expressions will typically make for the smallest code size, but some features such as UTF-8 and \w, \d, \s are not supported, and null characters in strings are not supported.

See regex(3) and regex(7) for full details.

Jim built-in Regular Expressions

The Jim built-in regular expression engine may be selected with ./configure --with-jim-regexp or it will be selected automatically if UTF-8 support is enabled.

This engine supports UTF-8 as well as some ARE features. The differences with both Tcl 7.x/8.x and POSIX are highlighted below.

  1. UTF-8 strings and patterns are both supported

  2. All Tcl character classes are supported (e.g. [:alnum:], [:digit:], [:space:]), but…

  3. Character classes apply to ASCII characters only

  4. Supported shorthand character classes: \w = [:alnum:], \W = [:alnum:], \d = [:digit:], \D = [:digit:], \s = [:space:], + \S = ^[:space:]

  5. Supported constraint escapes: \m = \< = start of word, \M = \> = end of word

  6. Backslash escapes may be used within regular expressions, such as \n = newline, \uNNNN = unicode

  7. Partially supported constraint escapes: \A = start of string, \Z = end of string

  8. Support for the ? non-greedy quantifier. e.g. *?

  9. Support for non-capturing parentheses (?:…)

  10. Jim Tcl considers that both patterns and strings end at a null character (\x00)

COMMAND RESULTS

Each command produces two results: a code and a string. The code indicates whether the command completed successfully or not, and the string gives additional information. The valid codes are defined in jim.h, and are:

JIM_OK(0)

This is the normal return code, and indicates that the command completed successfully. The string gives the command’s return value.

JIM_ERR(1)

Indicates that an error occurred; the string gives a message describing the error.

JIM_RETURN(2)

Indicates that the return command has been invoked, and that the current procedure (or top-level command or source command) should return immediately. The string gives the return value for the procedure or command.

JIM_BREAK(3)

Indicates that the break command has been invoked, so the innermost loop should abort immediately. The string should always be empty.

JIM_CONTINUE(4)

Indicates that the continue command has been invoked, so the innermost loop should go on to the next iteration. The string should always be empty.

JIM_SIGNAL(5)

Indicates that a signal was caught while executing a commands. The string contains the name of the signal caught. See the signal and catch commands.

JIM_EXIT(6)

Indicates that the command called the exit command. The string contains the exit code.

Tcl programmers do not normally need to think about return codes, since JIM_OK is almost always returned. If anything else is returned by a command, then the Tcl interpreter immediately stops processing commands and returns to its caller. If there are several nested invocations of the Tcl interpreter in progress, then each nested command will usually return the error to its caller, until eventually the error is reported to the top-level application code. The application will then display the error message for the user.

In a few cases, some commands will handle certain error conditions themselves and not return them upwards. For example, the for command checks for the JIM_BREAK code; if it occurs, then for stops executing the body of the loop and returns JIM_OK to its caller. The for command also handles JIM_CONTINUE codes and the procedure interpreter handles JIM_RETURN codes. The catch command allows Tcl programs to catch errors and handle them without aborting command interpretation any further.

The info returncodes command may be used to programmatically map between return codes and names.

PROCEDURES

Tcl allows you to extend the command interface by defining procedures. A Tcl procedure can be invoked just like any other Tcl command (it has a name and it receives one or more arguments). The only difference is that its body isn’t a piece of C code linked into the program; it is a string containing one or more other Tcl commands.

The proc command is used to create a new Tcl command procedure:

proc name arglist ?statics? body

The new command is named name, and it replaces any existing command there may have been by that name. Whenever the new command is invoked, the contents of body will be executed by the Tcl interpreter.

arglist specifies the formal arguments to the procedure. It consists of a list, possibly empty, of the following argument specifiers:

name

Required Argument - A simple argument name.

{name default}

Optional Argument - A two-element list consisting of the argument name, followed by the default value, which will be used if the corresponding argument is not supplied.

&name

Reference Argument - The caller is expected to pass the name of an existing variable. An implicit upvar 1 origname name is done to make the variable available in the proc scope.

args

Variable Argument - The special name args, which is assigned all remaining arguments (including none) as a list. The variable argument may only be specified once. Note that the syntax {args newname} may be used to retain the special behaviour of args with a different local name. In this case, the variable is named newname rather than args.

When the command is invoked, a local variable will be created for each of the formal arguments to the procedure; its value will be the value of corresponding argument in the invoking command or the argument’s default value.

Arguments with default values need not be specified in a procedure invocation. However, there must be enough actual arguments for all required arguments, and there must not be any extra actual arguments (unless the Variable Argument is specified).

Actual arguments are assigned to formal arguments as in left-to-right order with the following precedence.

  1. Required Arguments (including Reference Arguments)

  2. Optional Arguments

  3. Variable Argument

The following example illustrates precedence. Assume a procedure declaration:

    proc p {{a A} args b {c C} d} {...}

This procedure requires at least two arguments, but can accept an unlimited number. The following table shows how various numbers of arguments are assigned. Values marked as - are assigned the default value.

Number of arguments a args b c d

2

-

-

1

-

2

3

1

-

2

-

3

4

1

-

2

3

4

5

1

2

3

4

5

6

1

2,3

4

5

6

When body is being executed, variable names normally refer to local variables, which are created automatically when referenced and deleted when the procedure returns. One local variable is automatically created for each of the procedure’s arguments. Global variables can be accessed by invoking the global command or via the :: prefix.

New in Jim

In addition to procedure arguments, Jim procedures may declare static variables. These variables scoped to the procedure and initialised at procedure definition. Either from the static variable definition, or from the enclosing scope.

Consider the following example:

    . set a 1
    . proc a {} {a {b 2}} {
        set c 1
        puts "$a $b $c"
        incr a
        incr b
        incr c
    }
    . a
    1 2 1
    . a
    2 3 1

The static variable a has no initialiser, so it is initialised from the enclosing scope with the value 1. (Note that it is an error if there is no variable with the same name in the enclosing scope). However b has an initialiser, so it is initialised to 2.

Unlike a local variable, the value of a static variable is retained across invocations of the procedure.

See the proc command for information on how to define procedures and what happens when they are invoked. See also NAMESPACES.

VARIABLES - SCALARS AND ARRAYS

Tcl allows the definition of variables and the use of their values either through $-style variable substitution, the set command, or a few other mechanisms.

Variables need not be declared: a new variable will automatically be created each time a new variable name is used.

Tcl supports two types of variables: scalars and arrays. A scalar variable has a single value, whereas an array variable can have any number of elements, each with a name (called its index) and a value.

Array indexes may be arbitrary strings; they need not be numeric. Parentheses are used refer to array elements in Tcl commands. For example, the command

    set x(first) 44

will modify the element of x whose index is first so that its new value is 44.

Two-dimensional arrays can be simulated in Tcl by using indexes that contain multiple concatenated values. For example, the commands

    set a(2,3) 1
    set a(3,6) 2

set the elements of a whose indexes are 2,3 and 3,6.

In general, array elements may be used anywhere in Tcl that scalar variables may be used.

If an array is defined with a particular name, then there may not be a scalar variable with the same name.

Similarly, if there is a scalar variable with a particular name then it is not possible to make array references to the variable.

To convert a scalar variable to an array or vice versa, remove the existing variable with the unset command.

The array command provides several features for dealing with arrays, such as querying the names of all the elements of the array and converting between an array and a list.

Variables may be either global or local. If a variable name is used when a procedure isn’t being executed, then it automatically refers to a global variable. Variable names used within a procedure normally refer to local variables associated with that invocation of the procedure. Local variables are deleted whenever a procedure exits. Either global command may be used to request that a name refer to a global variable for the duration of the current procedure (this is somewhat analogous to extern in C), or the variable may be explicitly scoped with the :: prefix. For example

    . set a 1
    . set b 2
    . proc p {} {
        set c 3
        global a

        puts "$a $::b $c"
    }
    . p

will output:

1 2 3

ARRAYS AS LISTS IN JIM

Unlike Tcl, Jim can automatically convert between a list (with an even number of elements) and an array value. This is similar to the way Tcl can convert between a string and a list.

For example:

  set a {1 one 2 two}
  puts $a(2)

will output:

  two

Thus array set is equivalent to set when the variable does not exist or is empty.

The reverse is also true where an array will be converted into a list.

  set a(1) one; set a(2) two
  puts $a

will output:

  1 one 2 two

DICTIONARY VALUES

Tcl 8.5 introduced the dict command, and Jim Tcl has added a version of this command. Dictionaries provide efficient access to key-value pairs, just like arrays, but dictionaries are pure values. This means that you can pass them to a procedure just as a list or a string. Tcl dictionaries are therefore much more like Tcl lists, except that they represent a mapping from keys to values, rather than an ordered sequence.

You can nest dictionaries, so that the value for a particular key consists of another dictionary. That way you can elegantly build complicated data structures, such as hierarchical databases. You can also combine dictionaries with other Tcl data structures. For instance, you can build a list of dictionaries that themselves contain lists.

Dictionaries are values that contain an efficient, order-preserving mapping from arbitrary keys to arbitrary values. Each key in the dictionary maps to a single value. They have a textual format that is exactly that of any list with an even number of elements, with each mapping in the dictionary being represented as two items in the list. When a command takes a dictionary and produces a new dictionary based on it (either returning it or writing it back into the variable that the starting dictionary was read from) the new dictionary will have the same order of keys, modulo any deleted keys and with new keys added on to the end. When a string is interpreted as a dictionary and it would otherwise have duplicate keys, only the last value for a particular key is used; the others are ignored, meaning that, "apple banana" and "apple carrot apple banana" are equivalent dictionaries (with different string representations).

Note that in Jim, arrays are implemented as dictionaries. Thus automatic conversion between lists and dictionaries applies as it does for arrays.

  . dict set a 1 one
  1 one
  . dict set a 2 two
  1 one 2 two
  . puts $a
  1 one 2 two
  . puts $a(2)
  two
  . dict set a 3 T three
  1 one 2 two 3 {T three}

See the dict command for more details.

NAMESPACES

Tcl added namespaces as a mechanism avoiding name clashes, especially in applications including a number of 3rd party components. While there is less need for namespaces in Jim Tcl (which does not strive to support large applications), it is convenient to provide a subset of the support for namespaces to easy porting code from Tcl.

Jim Tcl currently supports "light-weight" namespaces which should be adequate for most purposes. This feature is currently experimental. See README.namespaces for more information and the documentation of the namespace command.

GARBAGE COLLECTION, REFERENCES, LAMBDA FUNCTION

Unlike Tcl, Jim has some sophisticated support for functional programming. These are described briefly below.

More information may be found at http://wiki.tcl.tk/13847

References

A reference can be thought of as holding a value with one level of indirection, where the value may be garbage collected when unreferenced. Consider the following example:

    . set r [ref "One String" test]
    <reference.<test___>.00000000000000000000>
    . getref $r
    One String

The operation ref creates a references to the value specified by the first argument. (The second argument is a "type" used for documentation purposes).

The operation getref is the dereferencing operation which retrieves the value stored in the reference.

    . setref $r "New String"
    New String
    . getref $r
    New String

The operation setref replaces the value stored by the reference. If the old value is no longer accessible by any reference, it will eventually be automatically be garbage collected.

Garbage Collection

Normally, all values in Tcl are passed by value. As such values are copied and released automatically as necessary.

With the introduction of references, it is possible to create values whose lifetime transcend their scope. To support this, case, the Jim system will periodically identify and discard objects which are no longer accessible by any reference.

The collect command may be used to force garbage collection. Consider a reference created with a finalizer:

    . proc f {ref value} { puts "Finaliser called for $ref,$value" }
    . set r [ref "One String" test f]
    <reference.<test___>.00000000000
    . collect
    0
    . set r ""
    . collect
    Finaliser called for <reference.<test___>.00000000000,One String
    1

Note that once the reference, r, was modified so that it no longer contained a reference to the value, the garbage collector discarded the value (after calling the finalizer).

The finalizer for a reference may be examined or changed with the finalize command

    . finalize $r
    f
    . finalize $r newf
    newf

Lambda Function

Jim provides a garbage collected lambda function. This is a procedure which is able to create an anonymous procedure. Consider:

    . set f [lambda {a} {{x 0}} { incr x $a }]
    . $f 1
    1
    . $f 2
    3
    . set f ""

This create an anonymous procedure (with the name stored in f), with a static variable which is incremented by the supplied value and the result returned.

Once the procedure name is no longer accessible, it will automatically be deleted when the garbage collector runs.

The procedure may also be delete immediately by renaming it "". e.g.

    . rename $f ""

UTF-8 AND UNICODE

If Jim is built with UTF-8 support enabled (configure --enable-utf), then most string-related commands become UTF-8 aware. These include, but are not limited to, string match, split, glob, scan and format.

UTF-8 encoding has many advantages, but one of the complications is that characters can take a variable number of bytes. Thus the addition of string bytelength which returns the number of bytes in a string, while string length returns the number of characters.

If UTF-8 support is not enabled, all commands treat bytes as characters and string bytelength returns the same value as string length.

Note that even if UTF-8 support is not enabled, the \uNNNN and related syntax is still available to embed UTF-8 sequences.

Jim Tcl supports all currently defined unicode codepoints. That is 21 bits, up to +U+1FFFFF.

String Matching

Commands such as string match, lsearch -glob, array names and others use string pattern matching rules. These commands support UTF-8. For example:

  string match a\[\ua0-\ubf\]b "a\u00a3b"

format and scan

format %c allows a unicode codepoint to be be encoded. For example, the following will return a string with two bytes and one character. The same as \ub5

  format %c 0xb5

format respects widths as character widths, not byte widths. For example, the following will return a string with three characters, not three bytes.

  format %.3s \ub5\ub6\ub7\ub8

Similarly, scan … %c allows a UTF-8 to be decoded to a unicode codepoint. The following will set a to 181 (0xb5) and b to 65 (0x41).

  scan \u00b5A %c%c a b

scan %s will also accept a character class, including unicode ranges.

String Classes

string is has not been extended to classify UTF-8 characters. Therefore, the following will return 0, even though the string may be considered to be alphabetic.

  string is alpha \ub5Test

This does not affect the string classes ascii, control, digit, double, integer or xdigit.

Case Mapping and Conversion

Jim provides a simplified unicode case mapping. This means that case conversion and comparison will not increase or decrease the number of characters in a string. (Although it may change the number of bytes).

string toupper will convert any lowercase letters to their uppercase equivalent. Any character which is not a letter or has no uppercase equivalent is left unchanged. Similarly for string tolower and string totitle.

Commands which perform case insensitive matches, such as string compare -nocase and lsearch -nocase fold both strings to uppercase before comparison.

Invalid UTF-8 Sequences

Some UTF-8 character sequences are invalid, such as those beginning with 0xff, those which represent character sequences longer than 3 bytes (greater than U+FFFF), and those which end prematurely, such as a lone 0xc2.

In these situations, the offending bytes are treated as single characters. For example, the following returns 2.

  string bytelength \xff\xff

Regular Expressions

If UTF-8 support is enabled, the built-in regular expression engine will be selected which supports UTF-8 strings and patterns.

BUILT-IN COMMANDS

The Tcl library provides the following built-in commands, which will be available in any application using Tcl. In addition to these built-in commands, there may be additional commands defined by each application, plus commands defined as Tcl procedures.

In the command syntax descriptions below, words in boldface are literals that you type verbatim to Tcl.

Words in italics are meta-symbols; they serve as names for any of a range of values that you can type.

Optional arguments or groups of arguments are indicated by enclosing them in ?question-marks?.

Ellipses (...) indicate that any number of additional arguments or groups of arguments may appear, in the same format as the preceding argument(s).

alarm

alarm seconds

Delivers the SIGALRM signal to the process after the given number of seconds. If the platform supports ualarm(3) then the argument may be a floating point value. Otherwise it must be an integer.

Note that unless a signal handler for SIGALRM has been installed (see signal), the process will exit on this signal.

alias

alias name args...

Creates a single word alias (command) for one or more words. For example, the following creates an alias for the command info exists.

    alias e info exists
    if {[e var]} {
      ...
    }

alias returns name, allowing it to be used with local.

See also proc, curry, lambda, local, info alias, exists -alias

append

append varName value ?value value …?

Append all of the value arguments to the current value of variable varName. If varName doesn’t exist, it is given a value equal to the concatenation of all the value arguments.

This command provides an efficient way to build up long variables incrementally. For example, "append a $b" is much more efficient than "set a $a$b" if $a is long.

apply

apply lambdaExpr ?arg1 arg2 ...?

The command apply provides for anonymous procedure calls, similar to lambda, but without command name being created, even temporarily.

The function lambdaExpr is a two element list {args body} or a three element list {args body namespace}. The first element args specifies the formal arguments, in the same form as the proc and lambda commands.

array

array option arrayName ?arg...?

This command performs one of several operations on the variable given by arrayName.

Note that in general, if the named array does not exist, the array command behaves as though the array exists but is empty.

The option argument determines what action is carried out by the command. The legal options (which may be abbreviated) are:

array exists arrayName

Returns 1 if arrayName is an array variable, 0 if there is no variable by that name.

array get arrayName ?pattern?

Returns a list containing pairs of elements. The first element in each pair is the name of an element in arrayName and the second element of each pair is the value of the array element. The order of the pairs is undefined. If pattern is not specified, then all of the elements of the array are included in the result. If pattern is specified, then only those elements whose names match pattern (using the matching rules of string match) are included. If arrayName isn’t the name of an array variable, or if the array contains no elements, then an empty list is returned.

array names arrayName ?pattern?

Returns a list containing the names of all of the elements in the array that match pattern. If pattern is omitted then the command returns all of the element names in the array. If pattern is specified, then only those elements whose names match pattern (using the matching rules of string match) are included. If there are no (matching) elements in the array, or if arrayName isn’t the name of an array variable, then an empty string is returned.

array set arrayName list

Sets the values of one or more elements in arrayName. list must have a form like that returned by array get, consisting of an even number of elements. Each odd-numbered element in list is treated as an element name within arrayName, and the following element in list is used as a new value for that array element. If the variable arrayName does not already exist and list is empty, arrayName is created with an empty array value.

array size arrayName

Returns the number of elements in the array. If arrayName isn’t the name of an array then 0 is returned.

array unset arrayName ?pattern?

Unsets all of the elements in the array that match pattern (using the matching rules of string match). If arrayName isn’t the name of an array variable or there are no matching elements in the array, no error will be raised. If pattern is omitted and arrayName is an array variable, then the command unsets the entire array. The command always returns an empty string.

break

break

This command may be invoked only inside the body of a loop command such as for or foreach or while. It returns a JIM_BREAK code to signal the innermost containing loop command to return immediately.

case

The obsolete case command has been removed from Jim Tcl since v0.75. Use switch instead.

catch

catch ?-?no?code ...? ?--? command ?resultVarName? ?optionsVarName?

The catch command may be used to prevent errors from aborting command interpretation. catch evaluates command, and returns a JIM_OK code, regardless of any errors that might occur while executing command (with the possible exception of JIM_SIGNAL - see below).

The return value from catch is a decimal string giving the code returned by the Tcl interpreter after executing command. This will be 0 (JIM_OK) if there were no errors in command; otherwise it will have a non-zero value corresponding to one of the exceptional return codes (see jim.h for the definitions of code values, or the info returncodes command).

If the resultVarName argument is given, then it gives the name of a variable; catch will set the value of the variable to the string returned from command (either a result or an error message).

If the optionsVarName argument is given, then it gives the name of a variable; catch will set the value of the variable to a dictionary. For any return code other than JIM_RETURN, the value for the key -code will be set to the return code. For JIM_RETURN it will be set to the code given in return -code. Additionally, for the return code JIM_ERR, the value of the key -errorinfo will contain the current stack trace (the same result as info stacktrace), the value of the key -errorcode will contain the same value as the global variable $::errorCode, and the value of the key -level will be the current return level (see return -level). This can be useful to rethrow an error:

    if {[catch {...} msg opts]} {
        ...maybe do something with the error...
        incr opts(-level)
        return {*}$opts $msg
    }

Normally catch will not catch any of the codes JIM_EXIT, JIM_EVAL or JIM_SIGNAL. The set of codes which will be caught may be modified by specifying the one more codes before command.

e.g. To catch JIM_EXIT but not JIM_BREAK or JIM_CONTINUE

    catch -exit -nobreak -nocontinue -- { ... }

The use of -- is optional. It signifies that no more return code options follow.

Note that if a signal marked as signal handle is caught with catch -signal, the return value (stored in resultVarName) is name of the signal caught.

cd

cd dirName

Change the current working directory to dirName.

Returns an empty string.

This command can potentially be disruptive to an application, so it may be removed in some applications.

clock

clock seconds

Returns the current time as seconds since the epoch.

clock clicks

Returns the current time in "clicks", a system-dependent, high-resolution time.

clock microseconds

Returns the current time in microseconds.

clock milliseconds

Returns the current time in milliseconds.

clock format seconds ?-format format? ?-gmt boolean?

Format the given time (seconds since the epoch) according to the given format. See strftime(3) for supported formats. If no format is supplied, "%c" is used.

If boolean is true, processing is performed in UTC. If boolean is false (the default), processing is performeed in the local time zone.

clock scan str -format format ?-gmt boolean?

Scan the given time string using the given format string. See strptime(3) for supported formats. See clock format for the handling of -gmt.

close

close fileId

fileId close

Closes the file given by fileId. fileId must be the return value from a previous invocation of the open command; after this command, it should not be used anymore.

collect

collect

Normally reference garbage collection is automatically performed periodically. However it may be run immediately with the collect command.

See GARBAGE COLLECTION for more detail.

concat

concat arg ?arg ...?

This command treats each argument as a list and concatenates them into a single list. It permits any number of arguments. For example, the command

    concat a b {c d e} {f {g h}}

will return

    a b c d e f {g h}

as its result.

continue

continue

This command may be invoked only inside the body of a loop command such as for or foreach or while. It returns a JIM_CONTINUE code to signal the innermost containing loop command to skip the remainder of the loop’s body but continue with the next iteration of the loop.

curry

alias args...

Similar to alias except it creates an anonymous procedure (lambda) instead of a named procedure.

the following creates a local, unnamed alias for the command info exists.

    set e [local curry info exists]
    if {[$e var]} {
      ...
    }

curry returns the name of the procedure.

See also proc, alias, lambda, local.

dict

dict option ?arg...?

Performs one of several operations on dictionary values.

The option argument determines what action is carried out by the command. The legal options are:

dict create ?key value ...?

Create and return a new dictionary value that contains each of the key/value mappings listed as arguments (keys and values alternating, with each key being followed by its associated value.)

dict exists dictionary key ?key ...?

Returns a boolean value indicating whether the given key (or path of keys through a set of nested dictionaries) exists in the given dictionary value. This returns a true value exactly when dict get on that path will succeed.

dict get dictionary ?key ...?

Given a dictionary value (first argument) and a key (second argument), this will retrieve the value for that key. Where several keys are supplied, the behaviour of the command shall be as if the result of "dict get $dictVal $key" was passed as the first argument to dict get with the remaining arguments as second (and possibly subsequent) arguments. This facilitates lookups in nested dictionaries. If no keys are provided, dict would return a list containing pairs of elements in a manner similar to array get. That is, the first element of each pair would be the key and the second element would be the value for that key. It is an error to attempt to retrieve a value for a key that is not present in the dictionary.

dict keys dictionary ?pattern?

Returns a list of the keys in the dictionary. If pattern is specified, then only those keys whose names match pattern (using the matching rules of string match) are included.

dict merge ?dictionary ...?

Return a dictionary that contains the contents of each of the dictionary arguments. Where two (or more) dictionaries contain a mapping for the same key, the resulting dictionary maps that key to the value according to the last dictionary on the command line containing a mapping for that key.

dict set dictionaryName key ?key ...? value

This operation takes the name of a variable containing a dictionary value and places an updated dictionary value in that variable containing a mapping from the given key to the given value. When multiple keys are present, this operation creates or updates a chain of nested dictionaries.

dict size dictionary

Return the number of key/value mappings in the given dictionary value.

dict unset dictionaryName key ?key ...? value

This operation (the companion to dict set) takes the name of a variable containing a dictionary value and places an updated dictionary value in that variable that does not contain a mapping for the given key. Where multiple keys are present, this describes a path through nested dictionaries to the mapping to remove. At least one key must be specified, but the last key on the key-path need not exist. All other components on the path must exist.

dict with dictionaryName key ?key ...? script

Execute the Tcl script in script with the value for each key in dictionaryName mapped to a variable with the same name. Where one or more keys are given, these indicate a chain of nested dictionaries, with the innermost dictionary being the one opened out for the execution of body. Making dictionaryName unreadable will make the updates to the dictionary be discarded, and this also happens if the contents of dictionaryName are adjusted so that the chain of dictionaries no longer exists. The result of dict with is (unless some kind of error occurs) the result of the evaluation of body.

The variables are mapped in the scope enclosing the dict with; it is recommended that this command only be used in a local scope (procedure). Because of this, the variables set by dict with will continue to exist after the command finishes (unless explicitly unset). Note that changes to the contents of dictionaryName only happen when script terminates.

dict for, values, incr, append, lappend, update, info, replace to be documented…

env

env ?name? ?default?

If name is supplied, returns the value of name from the initial environment (see getenv(3)). An error is returned if name does not exist in the environment, unless default is supplied - in which case that value is returned instead.

If no arguments are supplied, returns a list of all environment variables and their values as {name value ...}

See also the global variable ::env

eof

eof fileId

fileId eof

Returns 1 if an end-of-file condition has occurred on fileId, 0 otherwise.

fileId must have been the return value from a previous call to open, or it may be stdin, stdout, or stderr to refer to one of the standard I/O channels.

error

error message ?stacktrace?

Returns a JIM_ERR code, which causes command interpretation to be unwound. message is a string that is returned to the application to indicate what went wrong.

If the stacktrace argument is provided and is non-empty, it is used to initialize the stacktrace.

This feature is most useful in conjunction with the catch command: if a caught error cannot be handled successfully, stacktrace can be used to return a stack trace reflecting the original point of occurrence of the error:

    catch {...} errMsg
    ...
    error $errMsg [info stacktrace]

See also errorInfo, info stacktrace, catch and return

errorInfo

errorInfo error ?stacktrace?

Returns a human-readable representation of the given error message and stack trace. Typical usage is:

    if {[catch {...} error]} {
        puts stderr [errorInfo $error [info stacktrace]]
        exit 1
    }

See also error.

eval

eval arg ?arg...?

eval takes one or more arguments, which together comprise a Tcl command (or collection of Tcl commands separated by newlines in the usual way). eval concatenates all its arguments in the same fashion as the concat command, passes the concatenated string to the Tcl interpreter recursively, and returns the result of that evaluation (or any error generated by it).

exec

exec arg ?arg...?

This command treats its arguments as the specification of one or more UNIX commands to execute as subprocesses. The commands take the form of a standard shell pipeline; | arguments separate commands in the pipeline and cause standard output of the preceding command to be piped into standard input of the next command (or |& for both standard output and standard error).

Under normal conditions the result of the exec command consists of the standard output produced by the last command in the pipeline followed by the standard error output.

If any of the commands writes to its standard error file, then this will be included in the result after the standard output of the last command.

Note that unlike Tcl, data written to standard error does not cause exec to return an error.

If any of the commands in the pipeline exit abnormally or are killed or suspended, then exec will return an error. If no standard error output was produced, or is redirected, the error message will include the normal result, as above, followed by error messages describing the abnormal terminations.

If any standard error output was produced, these abnormal termination messages are suppressed.

If the last character of the result or error message is a newline then that character is deleted from the result or error message for consistency with normal Tcl return values.

An arg may have one of the following special forms:

>filename

The standard output of the last command in the pipeline is redirected to the file. In this situation exec will normally return an empty string.

>>filename

As above, but append to the file.

>@fileId

The standard output of the last command in the pipeline is redirected to the given (writable) file descriptor (e.g. stdout, stderr, or the result of open). In this situation exec will normally return an empty string.

2>filename

The standard error of the last command in the pipeline is redirected to the file.

2>>filename

As above, but append to the file.

2>@fileId

The standard error of the last command in the pipeline is redirected to the given (writable) file descriptor.

2>@1

The standard error of the last command in the pipeline is redirected to the same file descriptor as the standard output.

>&filename

Both the standard output and standard error of the last command in the pipeline is redirected to the file.

>>&filename

As above, but append to the file.

<filename

The standard input of the first command in the pipeline is taken from the file.

<<string

The standard input of the first command is taken as the given immediate value.

<@fileId

The standard input of the first command in the pipeline is taken from the given (readable) file descriptor.

If there is no redirection of standard input, standard error or standard output, these are connected to the corresponding input or output of the application.

If the last arg is & then the command will be executed in background. In this case the standard output from the last command in the pipeline will go to the application’s standard output unless redirected in the command, and error output from all the commands in the pipeline will go to the application’s standard error file. The return value of exec in this case is a list of process ids (pids) in the pipeline.

Each arg becomes one word for a command, except for |, <, <<, >, and & arguments, and the arguments that follow <, <<, and >.

The first word in each command is taken as the command name; the directories in the PATH environment variable are searched for an executable by the given name.

No glob expansion or other shell-like substitutions are performed on the arguments to commands.

If the command fails, the global $::errorCode (and the -errorcode option in catch) will be set to a list, as follows:

CHILDKILLED pid sigName msg

This format is used when a child process has been killed because of a signal. The pid element will be the process’s identifier (in decimal). The sigName element will be the symbolic name of the signal that caused the process to terminate; it will be one of the names from the include file signal.h, such as SIGPIPE. The msg element will be a short human-readable message describing the signal, such as "write on pipe with no readers" for SIGPIPE.

CHILDSUSP pid sigName msg

This format is used when a child process has been suspended because of a signal. The pid element will be the process’s identifier, in decimal. The sigName element will be the symbolic name of the signal that caused the process to suspend; this will be one of the names from the include file signal.h, such as SIGTTIN. The msg element will be a short human-readable message describing the signal, such as "background tty read" for SIGTTIN.

CHILDSTATUS pid code

This format is used when a child process has exited with a non-zero exit status. The pid element will be the process’s identifier (in decimal) and the code element will be the exit code returned by the process (also in decimal).

The environment for the executed command is set from $::env (unless this variable is unset, in which case the original environment is used).

exists

exists ?-var|-proc|-command|-alias? name

Checks the existence of the given variable, procedure, command or alias respectively and returns 1 if it exists or 0 if not. This command provides a more simplified/convenient version of info exists, info procs and info commands.

If the type is omitted, a type of -var is used. The type may be abbreviated.

exit

exit ?returnCode?

Terminate the process, returning returnCode to the parent as the exit status.

If returnCode isn’t specified then it defaults to 0.

Note that exit can be caught with catch.

expr

expr arg

Calls the expression processor to evaluate arg, and returns the result as a string. See the section EXPRESSIONS above.

Note that Jim supports a shorthand syntax for expr as $(...) The following two are identical.

  set x [expr {3 * 2 + 1}]
  set x $(3 * 2 + 1)

file

file option name ?arg...?

Operate on a file or a file name. name is the name of a file.

option indicates what to do with the file name. Any unique abbreviation for option is acceptable. The valid options are:

file atime name

Return a decimal string giving the time at which file name was last accessed. The time is measured in the standard UNIX fashion as seconds from a fixed starting time (often January 1, 1970). If the file doesn’t exist or its access time cannot be queried then an error is generated.

file copy ?-force? source target

Copies file source to file target. The source file must exist. The target file must not exist, unless -force is specified.

file delete ?-force? ?--? name...

Deletes file or directory name. If the file or directory doesn’t exist, nothing happens. If it can’t be deleted, an error is generated. Non-empty directories will not be deleted unless the -force options is given. In this case no errors will be generated, even if the file/directory can’t be deleted. Use -- if there is any possibility of the first name being -force.

file dirname name

Return all of the characters in name up to but not including the last slash character. If there are no slashes in name then return . (a single dot). If the last slash in name is its first character, then return /.

file executable name

Return 1 if file name is executable by the current user, 0 otherwise.

file exists name

Return 1 if file name exists and the current user has search privileges for the directories leading to it, 0 otherwise.

file extension name

Return all of the characters in name after and including the last dot in name. If there is no dot in name then return the empty string.

file isdirectory name

Return 1 if file name is a directory, 0 otherwise.

file isfile name

Return 1 if file name is a regular file, 0 otherwise.

file join arg...

Joins multiple path components. Note that if any components is an absolute path, the preceding components are ignored. Thus "file join /tmp /root" returns "/root".

file link ?-hard|-symbolic? newname target

Creates a hard link (default) or symbolic link from newname to target. Note that the sense of this command is the opposite of file rename and file copy and also of ln, but this is compatible with Tcl. An error is returned if target doesn’t exist or newname already exists.

file lstat name varName

Same as stat option (see below) except uses the lstat kernel call instead of stat. This means that if name refers to a symbolic link the information returned in varName is for the link rather than the file it refers to. On systems that don’t support symbolic links this option behaves exactly the same as the stat option.

file mkdir dir1 ?dir2...?

Creates each directory specified. For each pathname dir specified, this command will create all non-existing parent directories as well as dir itself. If an existing directory is specified, then no action is taken and no error is returned. Trying to overwrite an existing file with a directory will result in an error. Arguments are processed in the order specified, halting at the first error, if any.

file mtime name ?time?

Return a decimal string giving the time at which file name was last modified. The time is measured in the standard UNIX fashion as seconds from a fixed starting time (often January 1, 1970). If the file doesn’t exist or its modified time cannot be queried then an error is generated. If time is given, sets the modification time of the file to the given value.

file mtimeus name ?time_us?

As for file mtime except the time value is in microseconds since the epoch (see also clock microseconds). Note that some platforms and some filesystems don’t support high resolution timestamps for files.

file normalize name

Return the normalized path of name. See realpath(3).

file owned name

Return 1 if file name is owned by the current user, 0 otherwise.

file readable name

Return 1 if file name is readable by the current user, 0 otherwise.

file readlink name

Returns the value of the symbolic link given by name (i.e. the name of the file it points to). If name isn’t a symbolic link or its value cannot be read, then an error is returned. On systems that don’t support symbolic links this option is undefined.

file rename ?-force? oldname newname

Renames the file from the old name to the new name. If newname already exists, an error is returned unless -force is specified.

file rootname name

Return all of the characters in name up to but not including the last . character in the name. If name doesn’t contain a dot, then return name.

file split name

Returns a list whose elements are the path components in name. The first element of the list will have the same path type as name. All other elements will be relative. Path separators will be discarded.

file stat name ?varName?

Invoke the stat kernel call on name, and return the result as a dictionary with the following keys: atime, ctime, dev, gid, ino, mode, mtime, nlink, size, type, uid, mtimeus (if supported - see file mtimeus) Each element except type is a decimal string with the value of the corresponding field from the stat return structure; see the manual entry for stat for details on the meanings of the values. The type element gives the type of the file in the same form returned by the command file type. If varName is specified, it is taken to be the name of an array variable and the values are also stored into the array.

file tail name

Return all of the characters in name after the last slash. If name contains no slashes then return name.

file tempfile ?template?

Creates and returns the name of a unique temporary file. If template is omitted, a default template will be used to place the file in /tmp. See mkstemp(3) for the format of the template and security concerns.

file type name

Returns a string giving the type of file name, which will be one of file, directory, characterSpecial, blockSpecial, fifo, link, or socket.

file writable name

Return 1 if file name is writable by the current user, 0 otherwise.

The file commands that return 0/1 results are often used in conditional or looping commands, for example:

    if {![file exists foo]} {
        error {bad file name}
    } else {
        ...
    }

finalize

finalize reference ?command?

If command is omitted, returns the finalizer command for the given reference.

Otherwise, sets a new finalizer command for the given reference. command may be the empty string to remove the current finalizer.

The reference must be a valid reference create with the ref command.

See GARBAGE COLLECTION for more detail.

flush

flush fileId

fileId flush

Flushes any output that has been buffered for fileId. fileId must have been the return value from a previous call to open, or it may be stdout or stderr to access one of the standard I/O streams; it must refer to a file that was opened for writing. This command returns an empty string.

for

for start test next body

for is a looping command, similar in structure to the C for statement. The start, next, and body arguments must be Tcl command strings, and test is an expression string.

The for command first invokes the Tcl interpreter to execute start. Then it repeatedly evaluates test as an expression; if the result is non-zero it invokes the Tcl interpreter on body, then invokes the Tcl interpreter on next, then repeats the loop. The command terminates when test evaluates to 0.

If a continue command is invoked within body then any remaining commands in the current execution of body are skipped; processing continues by invoking the Tcl interpreter on next, then evaluating test, and so on.

If a break command is invoked within body or next, then the for command will return immediately.

The operation of break and continue are similar to the corresponding statements in C.

for returns an empty string.

foreach

foreach varName list body

foreach varList list ?varList2 list2 ...? body

In this command, varName is the name of a variable, list is a list of values to assign to varName, and body is a collection of Tcl commands.

For each field in list (in order from left to right), foreach assigns the contents of the field to varName (as if the lindex command had been used to extract the field), then calls the Tcl interpreter to execute body.

If instead of being a simple name, varList is used, multiple assignments are made each time through the loop, one for each element of varList.

For example, if there are two elements in varList and six elements in the list, the loop will be executed three times.

If the length of the list doesn’t evenly divide by the number of elements in varList, the value of the remaining variables in the last iteration of the loop are undefined.

The break and continue statements may be invoked inside body, with the same effect as in the for command.

foreach returns an empty string.

format

format formatString ?arg ...?

This command generates a formatted string in the same way as the C sprintf procedure (it uses sprintf in its implementation). formatString indicates how to format the result, using % fields as in sprintf, and the additional arguments, if any, provide values to be substituted into the result.

All of the sprintf options are valid; see the sprintf man page for details. Each arg must match the expected type from the % field in formatString; the format command converts each argument to the correct type (floating, integer, etc.) before passing it to sprintf for formatting.

The only unusual conversion is for %c; in this case the argument must be a decimal string, which will then be converted to the corresponding ASCII (or UTF-8) character value.

In addition, Jim Tcl provides basic support for conversion to binary with %b.

format does backslash substitution on its formatString argument, so backslash sequences in formatString will be handled correctly even if the argument is in braces.

The return value from format is the formatted string.

getref

getref reference

Returns the string associated with reference. The reference must be a valid reference create with the ref command.

See GARBAGE COLLECTION for more detail.

gets

gets fileId ?varName?

fileId gets ?varName?

Reads the next line from the file given by fileId and discards the terminating newline character.

If varName is specified, then the line is placed in the variable by that name and the return value is a count of the number of characters read (not including the newline).

If the end of the file is reached before reading any characters then -1 is returned and varName is set to an empty string.

If varName is not specified then the return value will be the line (minus the newline character) or an empty string if the end of the file is reached before reading any characters.

An empty string will also be returned if a line contains no characters except the newline, so eof may have to be used to determine what really happened.

If the last character in the file is not a newline character, then gets behaves as if there were an additional newline character at the end of the file.

fileId must be stdin or the return value from a previous call to open; it must refer to a file that was opened for reading.

glob

glob ?-nocomplain? ?-directory dir? ?-tails? ?--? pattern ?pattern ...?

This command performs filename globbing, using csh rules. The returned value from glob is the list of expanded filenames.

If -nocomplain is specified as the first argument then an empty list may be returned; otherwise an error is returned if the expanded list is empty. The -nocomplain argument must be provided exactly: an abbreviation will not be accepted.

If -directory is given, the dir is understood to contain a directory name to search in. This allows globbing inside directories whose names may contain glob-sensitive characters. The returned names include the directory name unless -tails is specified.

If -tails is specified, along with -directory, the returned names are relative to the given directory.

global

global varName ?varName ...?

This command is ignored unless a Tcl procedure is being interpreted. If so, then it declares each given varName to be a global variable rather than a local one. For the duration of the current procedure (and only while executing in the current procedure), any reference to varName will be bound to a global variable instead of a local one.

An alternative to using global is to use the :: prefix to explicitly name a variable in the global scope.

if

if expr1 ?then? body1 elseif expr2 ?then? body2 elseif ... ?else? ?bodyN?

The if command evaluates expr1 as an expression (in the same way that expr evaluates its argument). The value of the expression must be numeric; if it is non-zero then body1 is executed by passing it to the Tcl interpreter.

Otherwise expr2 is evaluated as an expression and if it is non-zero then body2 is executed, and so on.

If none of the expressions evaluates to non-zero then bodyN is executed.

The then and else arguments are optional "noise words" to make the command easier to read.

There may be any number of elseif clauses, including zero. bodyN may also be omitted as long as else is omitted too.

The return value from the command is the result of the body script that was executed, or an empty string if none of the expressions was non-zero and there was no bodyN.

incr

incr varName ?increment?

Increment the value stored in the variable whose name is varName. The value of the variable must be integral.

If increment is supplied then its value (which must be an integer) is added to the value of variable varName; otherwise 1 is added to varName.

The new value is stored as a decimal string in variable varName and also returned as result.

If the variable does not exist, the variable is implicitly created and set to 0 first.

info

info option ?arg...?

Provide information about various internals to the Tcl interpreter. The legal option's (which may be abbreviated) are:

info args procname

Returns a list containing the names of the arguments to procedure procname, in order. procname must be the name of a Tcl command procedure.

info alias command

command must be an alias created with alias. In which case the target command and arguments, as passed to alias are returned. See exists -alias

info body procname

Returns the body of procedure procname. procname must be the name of a Tcl command procedure.

info channels

Returns a list of all open file handles from open or socket

info commands ?pattern?

If pattern isn’t specified, returns a list of names of all the Tcl commands, including both the built-in commands written in C and the command procedures defined using the proc command. If pattern is specified, only those names matching pattern are returned. Matching is determined using the same rules as for string match.

info complete command ?missing?

Returns 1 if command is a complete Tcl command in the sense of having no unclosed quotes, braces, brackets or array element names, If the command doesn’t appear to be complete then 0 is returned. This command is typically used in line-oriented input environments to allow users to type in commands that span multiple lines; if the command isn’t complete, the script can delay evaluating it until additional lines have been typed to complete the command. If varName is specified, the missing character is stored in the variable with that name.

info exists varName

Returns 1 if the variable named varName exists in the current context (either as a global or local variable), returns 0 otherwise.

info frame ?number?

If number is not specified, this command returns a number which is the same result as info level - the current stack frame level. If number is specified, then the result is a list consisting of the procedure, filename and line number for the procedure call at level number on the stack. If number is positive then it selects a particular stack level (1 refers to the top-most active procedure, 2 to the procedure it called, and so on); otherwise it gives a level relative to the current level (0 refers to the current procedure, -1 to its caller, and so on). The level has an identical meaning to info level.

info globals ?pattern?

If pattern isn’t specified, returns a list of all the names of currently-defined global variables. If pattern is specified, only those names matching pattern are returned. Matching is determined using the same rules as for string match.

info hostname

An alias for os.gethostname for compatibility with Tcl 6.x

info level ?number?

If number is not specified, this command returns a number giving the stack level of the invoking procedure, or 0 if the command is invoked at top-level. If number is specified, then the result is a list consisting of the name and arguments for the procedure call at level number on the stack. If number is positive then it selects a particular stack level (1 refers to the top-most active procedure, 2 to the procedure it called, and so on); otherwise it gives a level relative to the current level (0 refers to the current procedure, -1 to its caller, and so on). See the uplevel command for more information on what stack levels mean.

info locals ?pattern?

If pattern isn’t specified, returns a list of all the names of currently-defined local variables, including arguments to the current procedure, if any. Variables defined with the global and upvar commands will not be returned. If pattern is specified, only those names matching pattern are returned. Matching is determined using the same rules as for string match.

info nameofexecutable

Returns the name of the binary file from which the application was invoked. A full path will be returned, unless the path can’t be determined, in which case the empty string will be returned.

info procs ?pattern?

If pattern isn’t specified, returns a list of all the names of Tcl command procedures. If pattern is specified, only those names matching pattern are returned. Matching is determined using the same rules as for string match.

info references

Returns a list of all references which have not yet been garbage collected.

info returncodes ?code?

Returns a list representing the mapping of standard return codes to names. e.g. {0 ok 1 error 2 return ...}. If a code is given, instead returns the name for the given code.

info script

If a Tcl script file is currently being evaluated (i.e. there is a call to Jim_EvalFile active or there is an active invocation of the source command), then this command returns the name of the innermost file being processed. Otherwise the command returns an empty string.

info source script ?filename line?

With a single argument, returns the original source location of the given script as a list of {filename linenumber}. If the source location can’t be determined, the list {{} 0} is returned. If filename and line are given, returns a copy of script with the associate source information. This can be useful to produce useful messages from eval, etc. if the original source information may be lost.

info stacktrace

After an error is caught with catch, returns the stack trace as a list of {procedure filename line ...}.

info statics procname

Returns a dictionary of the static variables of procedure procname. procname must be the name of a Tcl command procedure. An empty dictionary is returned if the procedure has no static variables.

info version

Returns the version number for this version of Jim in the form x.yy.

info vars ?pattern?

If pattern isn’t specified, returns a list of all the names of currently-visible variables, including both locals and currently-visible globals. If pattern is specified, only those names matching pattern are returned. Matching is determined using the same rules as for string match.

join

join list ?joinString?

The list argument must be a valid Tcl list. This command returns the string formed by joining all of the elements of list together with joinString separating each adjacent pair of elements.

The joinString argument defaults to a space character.

kill

kill ?SIG|-0? pid

Sends the given signal to the process identified by pid.

The signal may be specified by name or number in one of the following forms:

  • TERM

  • SIGTERM

  • -TERM

  • 15

  • -15

The signal name may be in either upper or lower case.

The special signal name -0 simply checks that a signal could be sent.

If no signal is specified, SIGTERM is used.

An error is raised if the signal could not be delivered.

lambda

lambda args ?statics? body

The lambda command is identical to proc, except rather than creating a named procedure, it creates an anonymous procedure and returns the name of the procedure.

See proc and GARBAGE COLLECTION for more detail.

lappend

lappend varName value ?value value ...?

Treat the variable given by varName as a list and append each of the value arguments to that list as a separate element, with spaces between elements.

If varName doesn’t exist, it is created as a list with elements given by the value arguments. lappend is similar to append except that each value is appended as a list element rather than raw text.

This command provides a relatively efficient way to build up large lists. For example,

    lappend a $b

is much more efficient than

    set a [concat $a [list $b]]

when $a is long.

lassign

lassign list varName ?varName ...?

This command treats the value list as a list and assigns successive elements from that list to the variables given by the varName arguments in order. If there are more variable names than list elements, the remaining variables are set to the empty string. If there are more list elements than variables, a list of unassigned elements is returned.

    . lassign {1 2 3} a b; puts a=$a,b=$b
    3
    a=1,b=2

local

local cmd ?arg...?

First, local evaluates cmd with the given arguments. The return value must be the name of an existing command, which is marked as having local scope. This means that when the current procedure exits, the specified command is deleted. This can be useful with lambda, local procedures or to automatically close a filehandle.

In addition, if a command already exists with the same name, the existing command will be kept rather than deleted, and may be called via upcall. The previous command will be restored when the current procedure exits. See upcall for more details.

In this example, a local procedure is created. Note that the procedure continues to have global scope while it is active.

    proc outer {} {
      # proc ... returns "inner" which is marked local
      local proc inner {} {
        # will be deleted when 'outer' exits
      }

      inner
      ...
    }

In this example, the lambda is deleted at the end of the procedure rather than waiting until garbage collection.

    proc outer {} {
      set x [lambda inner {args} {
        # will be deleted when 'outer' exits
      }]
      # Use 'function' here which simply returns $x
      local function $x

      $x ...
      ...
    }

loop

loop var first limit ?incr? body

Similar to for except simpler and possibly more efficient. With a positive increment, equivalent to:

    for {set var $first} {$var < $limit} {incr var $incr} $body

If incr is not specified, 1 is used. Note that setting the loop variable inside the loop does not affect the loop count.

lindex

lindex list ?index …?

Treats list as a Tcl list and returns element index from it (0 refers to the first element of the list). See STRING AND LIST INDEX SPECIFICATIONS for all allowed forms for index.

In extracting the element, lindex observes the same rules concerning braces and quotes and backslashes as the Tcl command interpreter; however, variable substitution and command substitution do not occur.

If no index values are given, simply returns list

If index is negative or greater than or equal to the number of elements in list, then an empty string is returned.

If additional index arguments are supplied, then each argument is used in turn to select an element from the previous indexing operation, allowing the script to select elements from sublists.

linsert

linsert list index element ?element element ...?

This command produces a new list from list by inserting all of the element arguments just before the element index of list. Each element argument will become a separate element of the new list. If index is less than or equal to zero, then the new elements are inserted at the beginning of the list. If index is greater than or equal to the number of elements in the list, then the new elements are appended to the list.

See STRING AND LIST INDEX SPECIFICATIONS for all allowed forms for index.

list

list arg ?arg ...?

This command returns a list comprised of all the arguments, arg. Braces and backslashes get added as necessary, so that the lindex command may be used on the result to re-extract the original arguments, and also so that eval may be used to execute the resulting list, with arg1 comprising the command’s name and the other args comprising its arguments. list produces slightly different results than concat: concat removes one level of grouping before forming the list, while list works directly from the original arguments. For example, the command

    list a b {c d e} {f {g h}}

will return

    a b {c d e} {f {g h}}

while concat with the same arguments will return

    a b c d e f {g h}

llength

llength list

Treats list as a list and returns a decimal string giving the number of elements in it.

lset

lset varName ?index ..? newValue

Sets an element in a list.

The lset command accepts a parameter, varName, which it interprets as the name of a variable containing a Tcl list. It also accepts zero or more indices into the list. Finally, it accepts a new value for an element of varName. If no indices are presented, the command takes the form:

    lset varName newValue

In this case, newValue replaces the old value of the variable varName.

When presented with a single index, the lset command treats the content of the varName variable as a Tcl list. It addresses the index’th element in it (0 refers to the first element of the list). When interpreting the list, lset observes the same rules concerning braces and quotes and backslashes as the Tcl command interpreter; however, variable substitution and command substitution do not occur. The command constructs a new list in which the designated element is replaced with newValue. This new list is stored in the variable varName, and is also the return value from the lset command.

If index is negative or greater than or equal to the number of elements in $varName, then an error occurs.

See STRING AND LIST INDEX SPECIFICATIONS for all allowed forms for index.

If additional index arguments are supplied, then each argument is used in turn to address an element within a sublist designated by the previous indexing operation, allowing the script to alter elements in sublists. The command,

    lset a 1 2 newValue

replaces element 2 of sublist 1 with newValue.

The integer appearing in each index argument must be greater than or equal to zero. The integer appearing in each index argument must be strictly less than the length of the corresponding list. In other words, the lset command cannot change the size of a list. If an index is outside the permitted range, an error is reported.

lmap

lmap varName list body

lmap varList list ?varList2 list2 ...? body

lmap is a "collecting" foreach which returns a list of its results.

For example:

    . lmap i {1 2 3 4 5} {expr $i*$i}
    1 4 9 16 25
    . lmap a {1 2 3} b {A B C} {list $a $b}
    {1 A} {2 B} {3 C}

If the body invokes continue, no value is added for this iteration. If the body invokes break, the loop ends and no more values are added.

load

load filename

Loads the dynamic extension, filename. Generally the filename should have the extension .so. The initialisation function for the module must be based on the name of the file. For example loading hwaccess.so will invoke the initialisation function, Jim_hwaccessInit. Normally the load command should not be used directly. Instead it is invoked automatically by package require.

lrange

lrange list first last

list must be a valid Tcl list. This command will return a new list consisting of elements first through last, inclusive.

See STRING AND LIST INDEX SPECIFICATIONS for all allowed forms for first and last.

If last is greater than or equal to the number of elements in the list, then it is treated as if it were end.

If first is greater than last then an empty string is returned.

Note: "lrange list first first" does not always produce the same result as "lindex list first" (although it often does for simple fields that aren’t enclosed in braces); it does, however, produce exactly the same results as "list [lindex list first]"

lreplace

lreplace list first last ?element element ...?

Returns a new list formed by replacing one or more elements of list with the element arguments.

first gives the index in list of the first element to be replaced.

If first is less than zero then it refers to the first element of list; the element indicated by first must exist in the list.

last gives the index in list of the last element to be replaced; it must be greater than or equal to first.

See STRING AND LIST INDEX SPECIFICATIONS for all allowed forms for first and last.

The element arguments specify zero or more new arguments to be added to the list in place of those that were deleted.

Each element argument will become a separate element of the list.

If no element arguments are specified, then the elements between first and last are simply deleted.

lrepeat

lrepeat number element1 ?element2 ...?

Build a list by repeating elements number times (which must be a positive integer).

    . lrepeat 3 a b
    a b a b a b

lreverse

lreverse list

Returns the list in reverse order.

    . lreverse {1 2 3}
    3 2 1

lsearch

lsearch ?options? list pattern

This command searches the elements list to see if one of them matches pattern. If so, the command returns the index of the first matching element (unless the options -all, -inline or -bool are specified.) If not, the command returns -1. The option arguments indicates how the elements of the list are to be matched against pattern and must have one of the values below:

Note that this command is different from Tcl in that default match type is -exact rather than -glob.

-exact

pattern is a literal string that is compared for exact equality against each list element. This is the default.

-glob

pattern is a glob-style pattern which is matched against each list element using the same rules as the string match command.

-regexp

pattern is treated as a regular expression and matched against each list element using the rules described by regexp.

-command cmdname

cmdname is a command which is used to match the pattern against each element of the list. It is invoked as cmdname ?-nocase? pattern listvalue and should return 1 for a match, or 0 for no match.

-all

Changes the result to be the list of all matching indices (or all matching values if -inline is specified as well). If indices are returned, the indices will be in numeric order. If values are returned, the order of the values will be the order of those values within the input list.

-inline

The matching value is returned instead of its index (or an empty string if no value matches). If -all is also specified, then the result of the command is the list of all values that matched. The -inline and -bool options are mutually exclusive.

-bool

Changes the result to 1 if a match was found, or 0 otherwise. If -all is also specified, the result will be a list of 0 and 1 for each element of the list depending upon whether the corresponding element matches. The -inline and -bool options are mutually exclusive.

-not

This negates the sense of the match, returning the index (or value if -inline is specified) of the first non-matching value in the list. If -bool is also specified, the 0 will be returned if a match is found, or 1 otherwise. If -all is also specified, non-matches will be returned rather than matches.

-nocase

Causes comparisons to be handled in a case-insensitive manner.

lsort

lsort ?-index listindex? ?-nocase|-integer|-real|-command cmdname? ?-unique? ?-decreasing|-increasing? list

Sort the elements of list, returning a new list in sorted order. By default, ASCII (or UTF-8) sorting is used, with the result in increasing order.

If -nocase is specified, comparisons are case-insensitive.

If -integer is specified, numeric sorting is used.

If -real is specified, floating point number sorting is used.

If -command cmdname is specified, cmdname is treated as a command name. For each comparison, cmdname $value1 $value2 is called which should compare the values and return an integer less than, equal to, or greater than zero if the $value1 is to be considered less than, equal to, or greater than $value2, respectively.

If -decreasing is specified, the resulting list is in the opposite order to what it would be otherwise. -increasing is the default.

If -unique is specified, then only the last set of duplicate elements found in the list will be retained. Note that duplicates are determined relative to the comparison used in the sort. Thus if -index 0 is used, {1 a} and {1 b} would be considered duplicates and only the second element, {1 b}, would be retained.

If -index listindex is specified, each element of the list is treated as a list and the given index is extracted from the list for comparison. The list index may be any valid list index, such as 1, end or end-2.

defer

defer script

This command is a simple helper command to add a script to the $jim::defer variable that will run when the current proc or interpreter exits. For example:

    . proc a {} { defer {puts "Leaving a"}; puts "Exit" }
    . a
    Exit
    Leaving a

If the $jim::defer variable exists, it is treated as a list of scripts to run when the proc or interpreter exits.

open

open fileName ?access?

open |command-pipeline ?access?

Opens a file and returns an identifier that may be used in future invocations of commands like read, puts, and close. fileName gives the name of the file to open.

The access argument indicates the way in which the file is to be accessed. It may have any of the following values:

r

Open the file for reading only; the file must already exist.

r+

Open the file for both reading and writing; the file must already exist.

w

Open the file for writing only. Truncate it if it exists. If it doesn’t exist, create a new file.

w+

Open the file for reading and writing. Truncate it if it exists. If it doesn’t exist, create a new file.

a

Open the file for writing only. The file must already exist, and the file is positioned so that new data is appended to the file.

a+

Open the file for reading and writing. If the file doesn’t exist, create a new empty file. Set the initial access position to the end of the file.

access defaults to r.

If a file is opened for both reading and writing, then seek must be invoked between a read and a write, or vice versa.

If the first character of fileName is "|" then the remaining characters of fileName are treated as a list of arguments that describe a command pipeline to invoke, in the same style as the arguments for exec. In this case, the channel identifier returned by open may be used to write to the command’s input pipe or read from its output pipe, depending on the value of access. If write-only access is used (e.g. access is w), then standard output for the pipeline is directed to the current standard output unless overridden by the command. If read-only access is used (e.g. access is r), standard input for the pipeline is taken from the current standard input unless overridden by the command.

The pid command may be used to return the process ids of the commands forming the command pipeline.

See also socket, pid, exec

package

package provide name ?version?

Indicates that the current script provides the package named name. If no version is specified, 1.0 is used.

Any script which provides a package may include this statement as the first statement, although it is not required.

package require name ?version?*

Searches for the package with the given name by examining each path in $::auto_path and trying to load $path/$name.so as a dynamic extension, or $path/$name.tcl as a script package.

The first such file which is found is considered to provide the package. (The version number is ignored).

If $name.so exists, it is loaded with the load command, otherwise if $name.tcl exists it is loaded with the source command.

If load or source fails, package require will fail immediately. No further attempt will be made to locate the file.

pid

pid

pid fileId

The first form returns the process identifier of the current process.

The second form accepts a handle returned by open and returns a list of the process ids forming the pipeline in the same form as exec ... &. If fileId represents a regular file handle rather than a command pipeline, the empty string is returned instead.

See also open, exec

proc

proc name args ?statics? body

The proc command creates a new Tcl command procedure, name. When the new command is invoked, the contents of body will be executed. Tcl interpreter. args specifies the formal arguments to the procedure. If specified, statics, declares static variables which are bound to the procedure.

See <<_procedures,PROCEDURES> for detailed information about Tcl procedures.

The proc command returns name (which is useful with local).

When a procedure is invoked, the procedure’s return value is the value specified in a return command. If the procedure doesn’t execute an explicit return, then its return value is the value of the last command executed in the procedure’s body.

If an error occurs while executing the procedure body, then the procedure-as-a-whole will return that same error.

puts

puts ?-nonewline? ?fileId? string

fileId puts ?-nonewline? string

Writes the characters given by string to the file given by fileId. fileId must have been the return value from a previous call to open, or it may be stdout or stderr to refer to one of the standard I/O channels; it must refer to a file that was opened for writing.

In the first form, if no fileId is specified then it defaults to stdout. puts normally outputs a newline character after string, but this feature may be suppressed by specifying the -nonewline switch.

Output to files is buffered internally by Tcl; the flush command may be used to force buffered characters to be output.

pipe

Creates a pair of aio channels and returns the handles as a list: {read write}

    lassign [pipe] r w

    # Must close $w after exec
    exec ps >@$w &
    $w close

    $r readable ...

pwd

pwd

Returns the path name of the current working directory.

rand

rand ?min? ?max?

Returns a random integer between min (defaults to 0) and max (defaults to the maximum integer).

If only one argument is given, it is interpreted as max.

range

range ?start? end ?step?

Returns a list of integers starting at start (defaults to 0) and ranging up to but not including end in steps of step defaults to 1).

    . range 5
    0 1 2 3 4
    . range 2 5
    2 3 4
    . range 2 10 4
    2 6
    . range 7 4 -2
    7 5

read

read ?-nonewline? fileId

fileId read ?-nonewline?

read fileId numBytes

fileId read numBytes

In the first form, all of the remaining bytes are read from the file given by fileId; they are returned as the result of the command. If the -nonewline switch is specified then the last character of the file is discarded if it is a newline.

In the second form, the extra argument specifies how many bytes to read; exactly this many bytes will be read and returned, unless there are fewer than numBytes bytes left in the file; in this case, all the remaining bytes are returned.

fileId must be stdin or the return value from a previous call to open; it must refer to a file that was opened for reading.

regexp

regexp ?-nocase? ?-line? ?-indices? ?-start offset? ?-all? ?-inline? ?--? exp string ?matchVar? ?subMatchVar subMatchVar ...?

Determines whether the regular expression exp matches part or all of string and returns 1 if it does, 0 if it doesn’t.

See REGULAR EXPRESSIONS above for complete information on the syntax of exp and how it is matched against string.

If additional arguments are specified after string then they are treated as the names of variables to use to return information about which part(s) of string matched exp. matchVar will be set to the range of string that matched all of exp. The first subMatchVar will contain the characters in string that matched the leftmost parenthesized subexpression within exp, the next subMatchVar will contain the characters that matched the next parenthesized subexpression to the right in exp, and so on.

Normally, matchVar and the each subMatchVar are set to hold the matching characters from string, however see -indices and -inline below.

If there are more values for subMatchVar than parenthesized subexpressions within exp, or if a particular subexpression in exp doesn’t match the string (e.g. because it was in a portion of the expression that wasn’t matched), then the corresponding subMatchVar will be set to "-1 -1" if -indices has been specified or to an empty string otherwise.

The following switches modify the behaviour of regexp

-nocase

Causes upper-case and lower-case characters to be treated as identical during the matching process.

-line

Use newline-sensitive matching. By default, newline is a completely ordinary character with no special meaning in either REs or strings. With this flag, [ bracket expressions and . never match newline, an anchor matches the null string after any newline in the string in addition to its normal function, and the $ anchor matches the null string before any newline in the string in addition to its normal function.

-indices

Changes what is stored in the subMatchVars. Instead of storing the matching characters from string, each variable will contain a list of two decimal strings giving the indices in string of the first and last characters in the matching range of characters.

-start offset

Specifies a character index offset into the string at which to start matching the regular expression. If -indices is specified, the indices will be indexed starting from the absolute beginning of the input string. offset will be constrained to the bounds of the input string.

-all

Causes the regular expression to be matched as many times as possible in the string, returning the total number of matches found. If this is specified with match variables, they will contain information for the last match only.

-inline

Causes the command to return, as a list, the data that would otherwise be placed in match variables. When using -inline, match variables may not be specified. If used with -all, the list will be concatenated at each iteration, such that a flat list is always returned. For each match iteration, the command will append the overall match data, plus one element for each subexpression in the regular expression.

--

Marks the end of switches. The argument following this one will be treated as exp even if it starts with a -.

regsub

regsub ?-nocase? ?-all? ?-line? ?-start offset? ?--? exp string subSpec ?varName?

This command matches the regular expression exp against string using the rules described in REGULAR EXPRESSIONS above.

If varName is specified, the commands stores string to varName with the substitutions detailed below, and returns the number of substitutions made (normally 1 unless -all is specified). This is 0 if there were no matches.

If varName is not specified, the substituted string will be returned instead.

When copying string, the portion of string that matched exp is replaced with subSpec. If subSpec contains a & or \0, then it is replaced in the substitution with the portion of string that matched exp.

If subSpec contains a \n, where n is a digit between 1 and 9, then it is replaced in the substitution with the portion of string that matched the n'-th parenthesized subexpression of exp. Additional backslashes may be used in subSpec to prevent special interpretation of & or \0 or \n or backslash.

The use of backslashes in subSpec tends to interact badly with the Tcl parser’s use of backslashes, so it’s generally safest to enclose subSpec in braces if it includes backslashes.

The following switches modify the behaviour of regsub

-nocase

Upper-case characters in string are converted to lower-case before matching against exp; however, substitutions specified by subSpec use the original unconverted form of string.

-all

All ranges in string that match exp are found and substitution is performed for each of these ranges, rather than only the first. The & and \n sequences are handled for each substitution using the information from the corresponding match.

-line

Use newline-sensitive matching. By default, newline is a completely ordinary character with no special meaning in either REs or strings. With this flag, [ bracket expressions and . never match newline, an anchor matches the null string after any newline in the string in addition to its normal function, and the $ anchor matches the null string before any newline in the string in addition to its normal function.

-start offset

Specifies a character index offset into the string at which to start matching the regular expression. offset will be constrained to the bounds of the input string.

--

Marks the end of switches. The argument following this one will be treated as exp even if it starts with a -.

ref

ref string tag ?finalizer?

Create a new reference containing string of type tag. If finalizer is specified, it is a command which will be invoked when the a garbage collection cycle runs and this reference is no longer accessible.

The finalizer is invoked as:

    finalizer reference string

See GARBAGE COLLECTION for more detail.

rename

rename oldName newName

Rename the command that used to be called oldName so that it is now called newName. If newName is an empty string (e.g. {}) then oldName is deleted. The rename command returns an empty string as result.

return

return ?-code code? ?-errorinfo stacktrace? ?-errorcode errorcode? ?-level n? ?value?

Return immediately from the current procedure (or top-level command or source command), with value as the return value. If value is not specified, an empty string will be returned as result.

If -code is specified (as either a number or ok, error, break, continue, signal, return or exit), this code will be used instead of JIM_OK. This is generally useful when implementing flow of control commands.

If -level is specified and greater than 1, it has the effect of delaying the new return code from -code. This is useful when rethrowing an error from catch. See the implementation of try/catch in tclcompat.tcl for an example of how this is done.

Note: The following options are only used when -code is JIM_ERR.

If -errorinfo is specified (as returned from info stacktrace) it is used to initialize the stacktrace.

If -errorcode is specified, it is used to set the global variable $::errorCode.

scan

scan string format varName1 ?varName2 ...?

This command parses fields from an input string in the same fashion as the C sscanf procedure. string gives the input to be parsed and format indicates how to parse it, using % fields as in sscanf. All of the sscanf options are valid; see the sscanf man page for details. Each varName gives the name of a variable; when a field is scanned from string, the result is converted back into a string and assigned to the corresponding varName. The only unusual conversion is for %c. For %c conversions a single character value is converted to a decimal string, which is then assigned to the corresponding varName; no field width may be specified for this conversion.

seek

seek fileId offset ?origin?

fileId seek offset ?origin?

Change the current access position for fileId. The offset and origin arguments specify the position at which the next read or write will occur for fileId. offset must be a number (which may be negative) and origin must be one of the following:

start

The new access position will be offset bytes from the start of the file.

current

The new access position will be offset bytes from the current access position; a negative offset moves the access position backwards in the file.

end

The new access position will be offset bytes from the end of the file. A negative offset places the access position before the end-of-file, and a positive offset places the access position after the end-of-file.

The origin argument defaults to start.

fileId must have been the return value from a previous call to open, or it may be stdin, stdout, or stderr to refer to one of the standard I/O channels.

This command returns an empty string.

set

set varName ?value?

Returns the value of variable varName.

If value is specified, then set the value of varName to value, creating a new variable if one doesn’t already exist, and return its value.

If varName contains an open parenthesis and ends with a close parenthesis, then it refers to an array element: the characters before the open parenthesis are the name of the array, and the characters between the parentheses are the index within the array. Otherwise varName refers to a scalar variable.

If no procedure is active, then varName refers to a global variable.

If a procedure is active, then varName refers to a parameter or local variable of the procedure, unless the global command has been invoked to declare varName to be global.

The :: prefix may also be used to explicitly reference a variable in the global scope.

setref

setref reference string

Store a new string in reference, replacing the existing string. The reference must be a valid reference create with the ref command.

See GARBAGE COLLECTION for more detail.

signal

Command for signal handling.

See kill for the different forms which may be used to specify signals.

Commands which return a list of signal names do so using the canonical form: "SIGINT SIGTERM".

signal handle ?signals ...?

If no signals are given, returns a list of all signals which are currently being handled. If signals are specified, these are added to the list of signals currently being handled.

signal ignore ?signals ...?

If no signals are given, returns a lists all signals which are currently being ignored. If signals are specified, these are added to the list of signals currently being ignored. These signals are still delivered, but are not considered by catch -signal or try -signal. Use signal check to determine which signals have occurred but been ignored.

signal block ?signals ...?

If no signals are given, returns a lists all signals which are currently being blocked. If signals are specified, these are added to the list of signals currently being blocked. These signals are not delivered to the process. This can be useful for signals such as SIGPIPE, especially in conjunction with exec as child processes inherit the parent’s signal disposition.

signal default ?signals ...?

If no signals are given, returns a lists all signals which currently have the default behaviour. If signals are specified, these are added to the list of signals which have the default behaviour.

signal check ?-clear? ?signals ...?

Returns a list of signals which have been delivered to the process but are ignored. If signals are specified, only that set of signals will be checked, otherwise all signals will be checked. If -clear is specified, any signals returned are removed and will not be returned by subsequent calls to signal check unless delivered again.

signal throw ?signal?

Raises the given signal, which defaults to SIGINT if not specified. The behaviour is identical to:

    kill signal [pid]

Note that signal handle and signal ignore represent two forms of signal handling. signal handle is used in conjunction with catch -signal or try -signal to immediately abort execution when the signal is delivered. Alternatively, signal ignore is used in conjunction with signal check to handle signal synchronously. Consider the two examples below.

Prevent a processing from taking too long

    signal handle SIGALRM
    alarm 20
    try -signal {
        .. possibly long running process ..
        alarm 0
    } on signal {sig} {
        puts stderr "Process took too long"
    }

Handle SIGHUP to reconfigure:

    signal ignore SIGHUP
    while {1} {
        ... handle configuration/reconfiguration ...
        while {[signal check -clear SIGHUP] eq ""} {
            ... do processing ..
        }
        # Received SIGHUP, so reconfigure
    }

Note: signal handling is currently not supported in child interpreters. In these interpreters, the signal command does not exist.

sleep

sleep seconds

Pauses for the given number of seconds, which may be a floating point value less than one to sleep for less than a second, or an integer to sleep for one or more seconds.

source

source fileName

Read file fileName and pass the contents to the Tcl interpreter as a sequence of commands to execute in the normal fashion. The return value of source is the return value of the last command executed from the file. If an error occurs in executing the contents of the file, then the source command will return that error.

If a return command is invoked from within the file, the remainder of the file will be skipped and the source command will return normally with the result from the return command.

split

split string ?splitChars?

Returns a list created by splitting string at each character that is in the splitChars argument.

Each element of the result list will consist of the characters from string between instances of the characters in splitChars.

Empty list elements will be generated if string contains adjacent characters in splitChars, or if the first or last character of string is in splitChars.

If splitChars is an empty string then each character of string becomes a separate element of the result list.

splitChars defaults to the standard white-space characters. For example,

    split "comp.unix.misc" .

returns "comp unix misc" and

    split "Hello world" {}

returns "H e l l o { } w o r l d".

stackdump

stackdump stacktrace

Creates a human readable representation of a stack trace.

stacktrace

stacktrace

Returns a live stack trace as a list of proc file line proc file line .... Iteratively uses info frame to create the stack trace. This stack trace is in the same form as produced by catch and info stacktrace

See also stackdump.

string

string option arg ?arg ...?

Perform one of several string operations, depending on option. The legal options (which may be abbreviated) are:

string bytelength string

Returns the length of the string in bytes. This will return the same value as string length if UTF-8 support is not enabled, or if the string is composed entirely of ASCII characters. See UTF-8 AND UNICODE.

string byterange string first last

Like string range except works on bytes rather than characters. These commands are identical if UTF-8 support is not enabled.

string cat ?string1 string2 ...?

Concatenates the given strings into a single string.

string compare ?-nocase? ?-length len? string1 string2

Perform a character-by-character comparison of strings string1 and string2 in the same way as the C strcmp procedure. Return -1, 0, or 1, depending on whether string1 is lexicographically less than, equal to, or greater than string2. If -length is specified, then only the first len characters are used in the comparison. If len is negative, it is ignored. Performs a case-insensitive comparison if -nocase is specified.

string equal ?-nocase? ?-length len? string1 string2

Returns 1 if the strings are equal, or 0 otherwise. If -length is specified, then only the first len characters are used in the comparison. If len is negative, it is ignored. Performs a case-insensitive comparison if -nocase is specified.

string first string1 string2 ?firstIndex?

Search string2 for a sequence of characters that exactly match the characters in string1. If found, return the index of the first character in the first such match within string2. If not found, return -1. If firstIndex is specified, matching will start from firstIndex of string1.

See STRING AND LIST INDEX SPECIFICATIONS for all allowed forms for firstIndex.

string index string charIndex

Returns the charIndexth character of the 'string argument. A charIndex of 0 corresponds to the first character of the string. If charIndex is less than 0 or greater than or equal to the length of the string then an empty string is returned.

See STRING AND LIST INDEX SPECIFICATIONS for all allowed forms for charIndex.

string is class ?-strict? string

Returns 1 if string is a valid member of the specified character class, otherwise returns 0. If -strict is specified, then an empty string returns 0, otherwise an empty string will return 1 on any class. The following character classes are recognized (the class name can be abbreviated):

alnum

Any alphabet or digit character.

alpha

Any alphabet character.

ascii

Any character with a value less than 128 (those that are in the 7-bit ascii range).

boolean

Any of the valid string formats for a boolean value in Tcl (0, false, no, off, 1, true, yes, on)

control

Any control character.

digit

Any digit character.

double

Any of the valid forms for a double in Tcl, with optional surrounding whitespace. In case of under/overflow in the value, 0 is returned.

graph

Any printing character, except space.

integer

Any of the valid string formats for an integer value in Tcl, with optional surrounding whitespace.

lower

Any lower case alphabet character.

print

Any printing character, including space.

punct

Any punctuation character.

space

Any space character.

upper

Any upper case alphabet character.

xdigit

Any hexadecimal digit character ([0-9A-Fa-f]).

Note that string classification does not respect UTF-8. See UTF-8 AND UNICODE.

Note that only lowercase boolean values are recognized (Tcl accepts any case).

string last string1 string2 ?lastIndex?

Search string2 for a sequence of characters that exactly match the characters in string1. If found, return the index of the first character in the last such match within string2. If there is no match, then return -1. If lastIndex is specified, only characters up to lastIndex of string2 will be considered in the match.

See STRING AND LIST INDEX SPECIFICATIONS for all allowed forms for lastIndex.

string length string

Returns a decimal string giving the number of characters in string. If UTF-8 support is enabled, this may be different than the number of bytes. See UTF-8 AND UNICODE.

string map ?-nocase? mapping string

Replaces substrings in string based on the key-value pairs in mapping, which is a list of key value key value ... as in the form returned by array get. Each instance of a key in the string will be replaced with its corresponding value. If -nocase is specified, then matching is done without regard to case differences. Both key and value may be multiple characters. Replacement is done in an ordered manner, so the key appearing first in the list will be checked first, and so on. string is only iterated over once, so earlier key replacements will have no affect for later key matches. For example,

      string map {abc 1 ab 2 a 3 1 0} 1abcaababcabababc

will return the string 01321221.

Note that if an earlier key is a prefix of a later one, it will completely mask the later one. So if the previous example is reordered like this,

      string map {1 0 ab 2 a 3 abc 1} 1abcaababcabababc

it will return the string 02c322c222c.

string match ?-nocase? pattern string

See if pattern matches string; return 1 if it does, 0 if it doesn’t. Matching is done in a fashion similar to that used by the C-shell. For the two strings to match, their contents must be identical except that the following special sequences may appear in pattern:

*

Matches any sequence of characters in string, including a null string.

?

Matches any single character in string.

[chars]

Matches any character in the set given by chars. If a sequence of the form x-y appears in chars, then any character between x and y, inclusive, will match.

\x

Matches the single character x. This provides a way of avoiding the special interpretation of the characters \*?[] in pattern.

Performs a case-insensitive comparison if -nocase is specified.

string range string first last

Returns a range of consecutive characters from string, starting with the character whose index is first and ending with the character whose index is last. An index of 0 refers to the first character of the string.

See STRING AND LIST INDEX SPECIFICATIONS for all allowed forms for first and last.

If first is less than zero then it is treated as if it were zero, and if last is greater than or equal to the length of the string then it is treated as if it were end. If first is greater than last then an empty string is returned.

string repeat string count

Returns a new string consisting of string repeated count times.

string replace string first last ?newstring?

Removes a range of consecutive characters from string, starting with the character whose index is first and ending with the character whose index is last. If newstring is specified, then it is placed in the removed character range. If first is less than zero then it is treated as if it were zero, and if last is greater than or equal to the length of the string then it is treated as if it were end. If first is greater than last or the length of the initial string, or last is less than 0, then the initial string is returned untouched.

string reverse string

Returns a string that is the same length as string but with its characters in the reverse order.

string tolower string

Returns a value equal to string except that all upper case letters have been converted to lower case.

string totitle string

Returns a value equal to string except that the first character is converted to title case (or upper case if there is no UTF-8 titlecase variant) and all remaining characters have been converted to lower case.

string toupper string

Returns a value equal to string except that all lower case letters have been converted to upper case.

string trim string ?chars?

Returns a value equal to string except that any leading or trailing characters from the set given by chars are removed. If chars is not specified then white space is removed (spaces, tabs, newlines, and carriage returns).

string trimleft string ?chars?

Returns a value equal to string except that any leading characters from the set given by chars are removed. If chars is not specified then white space is removed (spaces, tabs, newlines, and carriage returns).

string trimright string ?chars?

Returns a value equal to string except that any trailing characters from the set given by chars are removed. If chars is not specified then white space is removed (spaces, tabs, newlines, and carriage returns). Null characters are always removed.

subst

subst ?-nobackslashes? ?-nocommands? ?-novariables? string

This command performs variable substitutions, command substitutions, and backslash substitutions on its string argument and returns the fully-substituted result. The substitutions are performed in exactly the same way as for Tcl commands. As a result, the string argument is actually substituted twice, once by the Tcl parser in the usual fashion for Tcl commands, and again by the subst command.

If any of the -nobackslashes, -nocommands, or -novariables are specified, then the corresponding substitutions are not performed. For example, if -nocommands is specified, no command substitution is performed: open and close brackets are treated as ordinary characters with no special interpretation.

Note: when it performs its substitutions, subst does not give any special treatment to double quotes or curly braces. For example, the following script returns xyz {44}, not xyz {$a}.

    set a 44
    subst {xyz {$a}}

switch

switch ?options? string pattern body ?pattern body ...?

switch ?options? string {pattern body ?pattern body ...?}

The switch command matches its string argument against each of the pattern arguments in order. As soon as it finds a pattern that matches string it evaluates the following body and returns the result of that evaluation. If the last pattern argument is default then it matches anything. If no pattern argument matches string and no default is given, then the switch command returns an empty string. If the initial arguments to switch start with - then they are treated as options. The following options are currently supported:

-exact

Use exact matching when comparing string to a pattern. This is the default.

-glob

When matching string to the patterns, use glob-style matching (i.e. the same as implemented by the string match command).

-regexp

When matching string to the patterns, use regular expression matching (i.e. the same as implemented by the regexp command).

-command commandname

When matching string to the patterns, use the given command, which must be a single word. The command is invoked as commandname pattern string, or commandname -nocase pattern string and must return 1 if matched, or 0 if not.

--

Marks the end of options. The argument following this one will be treated as string even if it starts with a -.

Two syntaxes are provided for the pattern and body arguments. The first uses a separate argument for each of the patterns and commands; this form is convenient if substitutions are desired on some of the patterns or commands. The second form places all of the patterns and commands together into a single argument; the argument must have proper list structure, with the elements of the list being the patterns and commands. The second form makes it easy to construct multi-line switch commands, since the braces around the whole list make it unnecessary to include a backslash at the end of each line. Since the pattern arguments are in braces in the second form, no command or variable substitutions are performed on them; this makes the behaviour of the second form different than the first form in some cases.

If a body is specified as - it means that the body for the next pattern should also be used as the body for this pattern (if the next pattern also has a body of - then the body after that is used, and so on). This feature makes it possible to share a single body among several patterns.

Below are some examples of switch commands:

    switch abc a - b {format 1} abc {format 2} default {format 3}

will return 2,

    switch -regexp aaab {
           ^a.*b$ -
           b {format 1}
           a* {format 2}
           default {format 3}
    }

will return 1, and

    switch xyz {
           a -
           b {format 1}
           a* {format 2}
           default {format 3}
    }

will return 3.

tailcall

tailcall cmd ?arg...?

The tailcall command provides an optimised way of invoking a command whilst replacing the current call frame. This is similar to exec in Bourne Shell.

The following are identical except the first immediately replaces the current call frame.

  tailcall a b c
  return [uplevel 1 [list a b c]]

tailcall is useful as a dispatch mechanism:

  proc a {cmd args} {
    tailcall sub_$cmd {*}$args
  }
  proc sub_cmd1 ...
  proc sub_cmd2 ...

tell

tell fileId

fileId tell

Returns a decimal string giving the current access position in fileId.

fileId must have been the return value from a previous call to open, or it may be stdin, stdout, or stderr to refer to one of the standard I/O channels.

throw

throw code ?msg?

This command throws an exception (return) code along with an optional message. This command is mostly for convenient usage with try.

The command throw break is equivalent to break. The command throw 20 message can be caught with an on 20 ... clause to try.

time

time command ?count?

This command will call the Tcl interpreter count times to execute command (or once if count isn’t specified). It will then return a string of the form

    503 microseconds per iteration

which indicates the average amount of time required per iteration, in microseconds.

Time is measured in elapsed time, not CPU time.

try

try ?catchopts? tryscript ?on returncodes {?resultvar? ?optsvar?} handlerscript ...? ?finally finalscript?

The try command is provided as a convenience for exception handling.

This interpeter first evaluates tryscript under the effect of the catch options catchopts (e.g. -signal -noexit --, see catch).

It then evaluates the script for the first matching on handler (there many be zero or more) based on the return code from the try section. For example a normal JIM_ERR error will be matched by an on error handler.

Finally, any finalscript is evaluated.

The result of this command is the result of tryscript, except in the case where an exception occurs in a matching on handler script or the finally script, in which case the result is this new exception.

The specified returncodes is a list of return codes either as names (ok, error, break, etc.) or as integers.

If resultvar and optsvar are specified, they are set as for catch before evaluating the matching handler.

For example:

    set f [open input]
    try -signal {
        process $f
    } on {continue break} {} {
        error "Unexpected break/continue"
    } on error {msg opts} {
        puts "Dealing with error"
        return {*}$opts $msg
    } on signal sig {
        puts "Got signal: $sig"
    } finally {
        $f close
    }

If break, continue or error are raised, they are dealt with by the matching handler.

In any case, the file will be closed via the finally clause.

See also throw, catch, return, error.

unknown

unknown cmdName ?arg arg …?

This command doesn’t actually exist as part of Tcl, but Tcl will invoke it if it does exist.

If the Tcl interpreter encounters a command name for which there is not a defined command, then Tcl checks for the existence of a command named unknown.

If there is no such command, then the interpreter returns an error.

If the unknown command exists, then it is invoked with arguments consisting of the fully-substituted name and arguments for the original non-existent command.

The unknown command typically does things like searching through library directories for a command procedure with the name cmdName, or expanding abbreviated command names to full-length, or automatically executing unknown commands as UNIX sub-processes.

In some cases (such as expanding abbreviations) unknown will change the original command slightly and then (re-)execute it. The result of the unknown command is used as the result for the original non-existent command.

unset

unset ?-nocomplain? ?--? ?name name …?

Remove variables. Each name is a variable name, specified in any of the ways acceptable to the set command.

If a name refers to an element of an array, then that element is removed without affecting the rest of the array.

If a name consists of an array name with no parenthesized index, then the entire array is deleted.

The unset command returns an empty string as result.

An error occurs if any of the variables doesn’t exist, unless -nocomplain is specified. The -- argument may be specified to stop option processing in case the variable name may be -nocomplain.

upcall

upcall command ?args …?

May be used from within a proc defined as local proc in order to call the previous, hidden version of the same command.

If there is no previous definition of the command, an error is returned.

uplevel

uplevel ?level? command ?command …?

All of the command arguments are concatenated as if they had been passed to concat; the result is then evaluated in the variable context indicated by level. uplevel returns the result of that evaluation. If level is an integer, then it gives a distance (up the procedure calling stack) to move before executing the command. If level consists of # followed by a number then the number gives an absolute level number. If level is omitted then it defaults to 1. level cannot be defaulted if the first command argument starts with a digit or #.

For example, suppose that procedure a was invoked from top-level, and that it called b, and that b called c. Suppose that c invokes the uplevel command. If level is 1 or #2 or omitted, then the command will be executed in the variable context of b. If level is 2 or #1 then the command will be executed in the variable context of a.

If level is 3 or #0 then the command will be executed at top-level (only global variables will be visible). The uplevel command causes the invoking procedure to disappear from the procedure calling stack while the command is being executed. In the above example, suppose c invokes the command

    uplevel 1 {set x 43; d}

where d is another Tcl procedure. The set command will modify the variable x in b’s context, and 'd will execute at level 3, as if called from b. If it in turn executes the command

    uplevel {set x 42}

then the set command will modify the same variable x in b’s context: the procedure 'c does not appear to be on the call stack when d is executing. The command info level may be used to obtain the level of the current procedure.

uplevel makes it possible to implement new control constructs as Tcl procedures (for example, uplevel could be used to implement the while construct as a Tcl procedure).

upvar

upvar ?level? otherVar myVar ?otherVar myVar …?

This command arranges for one or more local variables in the current procedure to refer to variables in an enclosing procedure call or to global variables.

level may have any of the forms permitted for the uplevel command, and may be omitted if the first letter of the first otherVar isn’t # or a digit (it defaults to 1).

For each otherVar argument, upvar makes the variable by that name in the procedure frame given by level (or at global level, if level is #0) accessible in the current procedure by the name given in the corresponding myVar argument.

The variable named by otherVar need not exist at the time of the call; it will be created the first time myVar is referenced, just like an ordinary variable.

upvar may only be invoked from within procedures.

upvar returns an empty string.

The upvar command simplifies the implementation of call-by-name procedure calling and also makes it easier to build new control constructs as Tcl procedures. For example, consider the following procedure:

    proc add2 name {
        upvar $name x
        set x [expr $x+2]
    }

add2 is invoked with an argument giving the name of a variable, and it adds two to the value of that variable. Although add2 could have been implemented using uplevel instead of upvar, upvar makes it simpler for add2 to access the variable in the caller’s procedure frame.

wait

wait

wait -nohang pid

With no arguments, cleans up any processes started by exec ... & that have completed (reaps zombie processes).

With one or two arguments, waits for a process by id, either returned by exec ... & or by os.fork (if supported).

Waits for the process to complete, unless -nohang is specified, in which case returns immediately if the process is still running.

Returns a list of 3 elements.

{NONE x x} if the process does not exist or has already been waited for, or if -nohang is specified, and the process is still alive.

{CHILDSTATUS <pid> <exit-status>} if the process exited normally.

{CHILDKILLED <pid> <signal>} if the process terminated on a signal.

{CHILDSUSP <pid> none} if the process terminated for some other reason.

Note that on platforms supporting waitpid(2), pid can also be given special values such as 0 or -1. See waitpid(2) for more detail.

while

while test body

The while command evaluates test as an expression (in the same way that expr evaluates its argument). The value of the expression must be numeric; if it is non-zero then body is executed by passing it to the Tcl interpreter.

Once body has been executed then test is evaluated again, and the process repeats until eventually test evaluates to a zero numeric value. continue commands may be executed inside body to terminate the current iteration of the loop, and break commands may be executed inside body to cause immediate termination of the while command.

The while command always returns an empty string.

OPTIONAL-EXTENSIONS

The following extensions may or may not be available depending upon what options were selected when Jim Tcl was built.

posix: os.fork, os.gethostname, os.getids, os.uptime

os.fork

Invokes fork(2) and returns the result.

os.gethostname

Invokes gethostname(3) and returns the result.

os.getids

Returns the various user/group ids for the current process.

    . os.getids
    uid 1000 euid 1000 gid 100 egid 100
os.uptime

Returns the number of seconds since system boot. See description of uptime in sysinfo(2).

ANSI I/O (aio) and EVENTLOOP API

Jim provides an alternative object-based API for I/O.

See open and socket for commands which return an I/O handle.

aio

$handle accept ?addrvar?

Server socket only: Accept a connection and return stream. If addrvar is specified, the address of the connected client is stored in the named variable in the form addr:port for IP sockets or path for Unix domain sockets. See socket for details.

$handle buffering none|line|full

Sets the buffering mode of the stream.

$handle close ?r(ead)|w(rite)|-nodelete?

Closes the stream. The read and write arguments perform a "half-close" on a socket. See the shutdown(2) man page. The -nodelete option is applicable only for Unix domain sockets. It closes the socket but does not delete the bound path (e.g. after os.fork).

$handle copyto tofd ?size?

Copy bytes to the file descriptor tofd. If size is specified, at most that many bytes will be copied. Otherwise copying continues until the end of the input file. Returns the number of bytes actually copied.

$handle eof

Returns 1 if stream is at eof

$handle filename

Returns the original filename associated with the handle. Handles returned by socket give the socket type instead of a filename.

$handle flush

Flush the stream

$handle gets ?var?

Read one line and return it or store it in the var

$handle isatty

Returns 1 if the stream is a tty device.

$handle lock ?-wait?

Apply a POSIX lock to the open file associated with the handle using fcntl(F_SETLK), or fcntl(F_SETLKW) to wait for the lock to be available if -wait is specified. The handle must be open for write access. Returns 1 if the lock was successfully obtained, 0 otherwise. An error occurs if the handle is not suitable for locking (e.g. if it is not open for write)

$handle ndelay ?0|1?

Set O_NDELAY (if arg). Returns current/new setting. Note that in general ANSI I/O interacts badly with non-blocking I/O. Use with care.

$handle peername

Returns the remote address or path of the connected socket. See getpeername(2).

$handle puts ?-nonewline? str

Write the string, with newline unless -nonewline

$handle read ?-nonewline? ?len?

Read and return bytes from the stream. To eof if no len.

$handle recvfrom maxlen ?addrvar?

Receives a message from the handle via recvfrom(2) and returns it. At most maxlen bytes are read. If addrvar is specified, the sending address of the message is stored in the named variable in the form addr:port for IP sockets or path for Unix domain sockets. See socket for details.

$handle seek offset ?start|current|end?

Seeks in the stream (default current)

$handle sendto str ?address

Sends the string, str, to the given address (host:port or path) via the socket using sendto(2). This is intended for udp/dgram sockets and may give an error or behave in unintended ways for other handle types. Returns the number of bytes written.

$handle sockname

Returns the bound address or path of the socket. See getsockname(2).

$handle sockopt ?name value?

With no arguments, returns a dictionary of socket options currently set for the handle (will be empty for a non-socket). With name and value, sets the socket option to the given value. Currently supports the following boolean socket options: broadcast, debug, keepalive, nosigpipe, oobinline, tcp_nodelay, and the following integer socket options: sndbuf, rcvbuf

$handle sync

Flush the stream, then fsync(2) to commit any changes to storage. Only available on platforms that support fsync(2).

$handle tell

Returns the current seek position

$handle tty ?settings?

If no arguments are given, returns a dictionary containing the tty settings for the stream. If arguments are given, they must either be a dictionary, or setting value ... Abbrevations are supported for both settings and values, so the following is acceptable: $f tty parity e input c out raw. Only available on platforms that support termios(3). Supported settings are:

baud rate

Baud rate. e.g. 115200

data 5|6|7|8

Number of data bits

stop 1|2

Number of stop bits

parity even|odd|none

Parity setting

handshake xonxoff|rtscts|none

Handshaking type

input raw|cooked

Input character processing. In raw mode, the usual key sequences such as ^C do not generate signals.

output raw|cooked

Output character processing. Typically CR → CRNL is disabled in raw mode.

echo 0|1

Disable or enable echo on input. Note that this is a set-only value. Setting input to raw or cooked will overwrite this setting.

vmin numchars

Minimum number of characters to read.

vtime time

Timeout for noncanonical read (units of 0.1 seconds)

$handle ssl ?-server cert priv?

Upgrades the stream to a SSL/TLS session and returns the handle.

$handle unlock

Release a POSIX lock previously acquired by aio lock.

$handle verify

Verifies the certificate of a SSL/TLS stream peer

load_ssl_certs dir

Loads SSL/TLS CA certificates for use during verification

fconfigure

fconfigure handle ?-blocking 0|1? ?-buffering noneline|full? ?-translation mode?

For compatibility with Tcl, a limited form of the fconfigure command is supported.

eventloop: after, vwait, update

The following commands allow a script to be invoked when the given condition occurs. If no script is given, returns the current script. If the given script is the empty, the handler is removed.

$handle readable ?readable-script?

Sets or returns the script for when the socket is readable.

$handle writable ?writable-script?

Sets or returns the script for when the socket is writable.

$handle onexception ?exception-script?

Sets or returns the script for when oob data received.

For compatibility with Tcl, these may be prefixed with fileevent. e.g.

fileevent $handle readable ...

Time-based execution is also available via the eventloop API.

after ms

Sleeps for the given number of milliseconds. No events are processed during this time.

after ms|idle script ?script ...?

The scripts are concatenated and executed after the given number of milliseconds have elapsed. If idle is specified, the script will run the next time the event loop is processed with vwait or update. The script is only run once and then removed. Returns an event id.

after cancel id|command

Cancels an after event with the given event id or matching command (script). Returns the number of milliseconds remaining until the event would have fired. Returns the empty string if no matching event is found.

after info ?id?

If id is not given, returns a list of current after events. If id is given, returns a list containing the associated script and either timer or idle to indicated the type of the event. An error occurs if id does not match an event.

vwait variable

A call to vwait enters the eventloop. vwait processes events until the named (global) variable changes or all event handlers are removed. The variable need not exist beforehand. If there are no event handlers defined, vwait returns immediately.

update ?idletasks?

A call to update enters the eventloop to process expired events, but no new events. If idletasks is specified, only expired time events are handled, not file events. Returns once handlers have been run for all expired events.

Scripts are executed at the global scope. If an error occurs during a handler script, an attempt is made to call (the user-defined command) bgerror with the details of the error. If the bgerror command does not exist, the error message details are printed to stderr instead.

If a file event handler script generates an error, the handler is automatically removed to prevent infinite errors. (A time event handler is always removed after execution).

bgerror msg

Called when an event handler script generates an error. Note that the normal command resolution rules are used for bgerror. First the name is resolved in the current namespace, then in the global scope.

socket

Various socket types may be created.

socket unix path

A unix domain socket client connected to path

socket unix.server path

A unix domain socket server listening on path

socket unix.dgram ?path?

A unix domain socket datagram client, optionally connected to path

socket unix.dgram.server path

A unix domain socket datagram server server listening on path

socket ?-ipv6? stream addr:port

A TCP socket client. (See the forms for addr below)

socket ?-ipv6? stream.server ?addr:?port

A TCP socket server (addr defaults to 0.0.0.0 for IPv4 or [::] for IPv6).

socket ?-ipv6? dgram ?addr:port?

A UDP socket client. If the address is not specified, the client socket will be unbound and sendto must be used to indicated the destination.

socket ?-ipv6? dgram.server addr:port

A UDP socket server.

socket pipe

A synonym for pipe

socket pair

A socketpair (see socketpair(2)). Like pipe, this command returns a list of two channels: {s1 s2}. These channels are both readable and writable.

This command creates a socket connected (client) or bound (server) to the given address.

The returned value is channel and may generally be used with the various file I/O commands (gets, puts, read, etc.), either as object-based syntax or Tcl-compatible syntax.

    . set f [socket stream www.google.com:80]
    aio.sockstream1
    . $f puts -nonewline "GET / HTTP/1.0\r\n\r\n"
    . $f gets
    HTTP/1.0 302 Found
    . $f close

Server sockets, however support only accept, which is most useful in conjunction with the EVENTLOOP API.

    set f [socket stream.server 80]
    $f readable {
        set client [$f accept]
        $client gets $buf
        ...
        $client puts -nonewline "HTTP/1.1 404 Not found\r\n"
        $client close
    }
    vwait done

The address, addr, can be given in one of the following forms:

  1. For IPv4 socket types, an IPv4 address such as 192.168.1.1

  2. For IPv6 socket types, an IPv6 address such as [fe80::1234] or [::]

  3. A hostname

Note that on many systems, listening on an IPv6 address such as [::] will also accept requests via IPv4.

Where a hostname is specified, the first returned address is used which matches the socket type is used.

An unconnected dgram socket (either dgram or unix.dgram) must use sendto to specify the destination address.

The path for Unix domain sockets is automatically removed when the socket is closed. Use close -nodelete in the rare case where this behaviour should be avoided (e.g. after os.fork).

syslog

syslog ?options? ?priority? message

This command sends message to system syslog facility with given priority. Valid priorities are:

emerg, alert, crit, err, error, warning, notice, info, debug

If a message is specified, but no priority is specified, then a priority of info is used.

By default, facility user is used and the value of global tcl variable argv0 is used as ident string. However, any of the following options may be specified before priority to control these parameters:

-facility value

Use specified facility instead of user. The following values for facility are recognized:

authpriv, cron, daemon, kernel, lpr, mail, news, syslog, user,
uucp, local0-local7
-ident string

Use given string instead of argv0 variable for ident string.

-options integer

Set syslog options such as LOG_CONS, LOG_NDELAY. You should use numeric values of those from your system syslog.h file, because I haven’t got time to implement yet another hash table.

pack: pack, unpack

The optional pack extension provides commands to encode and decode binary strings.

pack varName value -intle|-intbe|-floatle|-floatbe|-str bitwidth ?bitoffset?

Packs the binary representation of value into the variable varName. The value is packed according to the given type (integer/floating point/string, big-endian/little-endian), width and bit offset. The variable is created if necessary (like append). The variable is expanded if necessary.

unpack binvalue -intbe|-intle|-uintbe|-uintle|-floatbe|-floatle|-str bitpos bitwidth

Unpacks bits from binvalue at bit position bitpos and with bitwidth. Interprets the value according to the type (integer/floating point/string, big-endian/little-endian and signed/unsigned) and returns it. For integer types, bitwidth may be up to the size of a Jim Tcl integer (typically 64 bits). For floating point types, bitwidth may be 32 bits (for single precision numbers) or 64 bits (for double precision). For the string type, both the width and the offset must be on a byte boundary (multiple of 8). Attempting to access outside the length of the value will return 0 for integer types, 0.0 for floating point types or the empty string for the string type.

zlib

The optional zlib extension provides a Tcl-compatible subset of the zlib command.

crc32 data ?startValue?

Returns the CRC32 checksum of a buffer. Optionally, an initial value may be specified; this is most useful for calculating the checksum of chunked data read from a stream (for instance, a pipe).

deflate string ?level?

Compresses a buffer and outputs a raw, Deflate-compressed stream. Optionally, a compression level (1-9) may be specified to choose the desired speed vs. compression rate ratio.

inflate data ?bufferSize?

Decompresses a raw, Deflate-compressed stream. When the uncompressed data size is known and specified, memory allocation is more efficient. Otherwise, decomperssion is chunked and therefore slower.

gzip string ?-level level?

Compresses a buffer and adds a gzip header.

gunzip data ?-buffersize size?

Decompresses a gzip-compressed buffer. Decompression is chunked, with a default, small buffer size of 64K which guarantees lower memory footprint at the cost of speed. It is recommended to use a bigger size, on systems without a severe memory constraint.

binary

The optional, pure-Tcl binary extension provides the Tcl-compatible binary scan and binary format commands based on the low-level pack and unpack commands.

Note that binary format with f/r/R specifiers (single-precision float) uses the value of Infinity in case of overflow.

oo: class, super

The optional, pure-Tcl oo extension provides object-oriented (OO) support for Jim Tcl.

See the online documentation (http://jim.tcl.tk/index.html/doc/www/www/documentation/oo/) for more details.

class classname ?baseclasses? classvars

Create a new class, classname, with the given dictionary (classvars) as class variables. These are the initial variables which all newly created objects of this class are initialised with. If a list of baseclasses is given, methods and instance variables are inherited.

super method ?args ...?

From within a method, invokes the given method on the base class. Note that this will only call the last baseclass given.

tree

The optional, pure-Tcl tree extension implements an OO, general purpose tree structure similar to that provided by tcllib ::struct::tree (http://core.tcl.tk/tcllib/doc/trunk/embedded/www/tcllib/files/modules/struct/struct_tree.html)

A tree is a collection of nodes, where each node (except the root node) has a single parent and zero or more child nodes (ordered), as well as zero or more attribute/value pairs.

tree

Creates and returns a new tree object with a single node named "root". All operations on the tree are invoked through this object.

$tree destroy

Destroy the tree and all it’s nodes. (Note that the tree will also be automatically garbage collected once it goes out of scope).

$tree set nodename key value

Set the value for the given attribute key.

$tree lappend nodename key value ...

Append to the (list) value(s) for the given attribute key, or set if not yet set.

$tree keyexists nodename key

Returns 1 if the given attribute key exists.

$tree get nodename key

Returns the value associated with the given attribute key.

$tree getall nodename

Returns the entire attribute dictionary associated with the given key.

$tree depth nodename

Returns the depth of the given node. The depth of "root" is 0.

$tree parent nodename

Returns the node name of the parent node, or "" for the root node.

$tree numchildren nodename

Returns the number of child nodes.

$tree children nodename

Returns a list of the child nodes.

$tree next nodename

Returns the next sibling node, or "" if none.

$tree insert nodename ?index?

Add a new child node to the given node. The index is a list index such as 3 or end-2. The default index is end. Returns the name of the newly added node.

$tree walk nodename dfs|bfs {actionvar nodevar} script

Walks the tree starting from the given node, either breadth first (bfs) depth first (dfs). The value "enter" or "exit" is stored in variable actionvar. The name of each node is stored in nodevar. The script is evaluated twice for each node, on entry and exit.

$tree dump

Dumps the tree contents to stdout

tcl::prefix

The optional tclprefix extension provides the Tcl8.6-compatible tcl::prefix command (http://www.tcl.tk/man/tcl8.6/TclCmd/prefix.htm) for matching strings against a table of possible values (typically commands or options).

tcl::prefix all table string

Returns a list of all elements in table that begin with the prefix string.

tcl::prefix longest table string

Returns the longest common prefix of all elements in table that begin with the prefix string.

tcl::prefix match ?options? table string

If string equals one element in table or is a prefix to exactly one element, the matched element is returned. If not, the result depends on the -error option.

  • -exact Accept only exact matches.

  • -message string Use string in the error message at a mismatch. Default is "option".

  • -error options The options are used when no match is found. If options is empty, no error is generated and an empty string is returned. Otherwise the options are used as return options when generating the error message. The default corresponds to setting -level 0.

tcl::autocomplete

Scriptable command line completion is supported in the interactive shell, jimsh, through the tcl::autocomplete callback. A simple implementation is provided, however this may be replaced with a custom command instead if desired.

In the interactive shell, press <TAB> to activate command line completion.

tcl::autocomplete commandline

This command is called with the current command line when the user presses <TAB>. The command should return a list of all possible command lines that match the current command line. For example if pr is the current command line, the list {prefix proc} may be returned.

history

The optional history extension provides script access to the command line editing and history support available in jimsh. See examples/jtclsh.tcl for an example. Note: if line editing support is not available, history getline acts like gets and the remaining subcommands do nothing.

history load filename

Load history from a (text) file. If the file does not exist or is not readable, it is ignored.

history getline prompt ?varname?

Displays the given prompt and allows a line to be entered. Similarly to gets, if varname is given, it receives the line and the length of the line is returned, or -1 on EOF. If varname is not given, the line is returned directly.

history completion command

Sets an autocompletion command (see tcl::autocomplete) that is active during history getline. If the command is empty, autocompletion is disabled.

history add line

Adds the given line to the history buffer.

history save filename

Saves the current history buffer to the given file.

history show

Displays the current history buffer to standard output.

namespace

Provides namespace-related functions. See also: http://www.tcl.tk/man/tcl8.6/TclCmd/namespace.htm

namespace code script

Captures the current namespace context for later execution of the script script. It returns a new script in which script has been wrapped in a namespace inscope command.

namespace current

Returns the fully-qualified name for the current namespace.

namespace delete ?namespace …?

Deletes all commands and variables with the given namespace prefixes.

namespace eval namespace arg ?arg…?

Activates a namespace called namespace and evaluates some code in that context.

namespace origin command

Returns the fully-qualified name of the original command to which the imported command command refers.

namespace parent ?namespace?

Returns the fully-qualified name of the parent namespace for namespace namespace, if given, otherwise for the current namespace.

namespace qualifiers string

Returns any leading namespace qualifiers for string

namespace tail string

Returns the simple name at the end of a qualified string.

namespace upvar namespace ?arg…?

This command arranges for zero or more local variables in the current procedure to refer to variables in namespace

namespace which ?-command|-variable? name

Looks up name as either a command (the default) or variable and returns its fully-qualified name.

interp

The optional interp command allows sub-interpreters to be created where commands may be run independently (but synchronously) of the main interpreter.

interp

Creates and returns a new interpreter object (command). The created interpeter contains any built-in commands along with static extensions, but does not include any dynamically loaded commands (package require, load). These must be reloaded in the child interpreter if required.

$interp delete

Deletes the interpeter object.

$interp eval script

Evaluates a script in the context for the child interpreter, in the same way as eval.

$interp alias alias childcmd parentcmd ?arg …?

Similar to alias, but creates a command, childcmd, in the child interpreter that is an alias for parentcmd in the parent interpreter, with the given, fixed arguments. The alias may be deleted in the child with rename.

json::encode

The Tcl → JSON encoder is part of the optional json package.

json::encode value ?schema?

Encode a Tcl value as JSON according to the schema (defaults to str). The following schema types are supported:

  • str - Tcl string → JSON string

  • num - Tcl value → bare numeric value or null

  • bool - Tcl boolean value → true, false

  • obj ?name subschema …? - Tcl dict → JSON object. For each dict key matching name, the corresponding subschema is applied. The special name * matches any keys not otherwise matched, otherwise the default str is used.

  • list ?subschema? - Tcl list → JSON array. The subschema (default str) is applied for each element of the list/array.

  • mixed ?subschema …? = Tcl list → JSON array. Each subschema is applied for the corresponding element of the list/array.

The following are examples:

    . json::encode {1 2 true false null 5.0} list
    [ "1", "2", "true", "false", "null", "5.0" ]
    . json::encode {1 2 true false null 5.0} {list num}
    [ 1, 2, true, false, null, 5.0 ]
    . json::encode {0 1 2 true false 5.0 off} {list bool}
    [ false, true, true, true, false, true, false ]
    . json::encode {a 1 b hello c {3 4}} obj
    { "a":"1", "b":"hello", "c":"3 4" }
    . json::encode {a 1 b hello c {3 4}} {obj a num c {list num}}
    { "a":1, "b":"hello", "c":[ 3, 4 ] }
    . json::encode {true true {abc def}} {mixed str num obj}
    [ "true", true, { "abc":"def" } ]
    . json::encode {a 1 b 3.0 c hello d null} {obj c str * num}
    { "a":1, "b":3.0, "c":"hello", "d":null }

json::decode

The JSON → Tcl decoder is part of the optional json package.

json::decode ?-index? ?-null string? ?-schema? json-string

Decodes the given JSON string (must be array or object) into a Tcl data structure. If -index is specified, decodes JSON arrays as dictionaries with numeric keys. This makes it possible to retrieve data from nested arrays and dictionaries with just dict get. With the option -schema returns a list of {data schema} where the schema is compatible with json::encode. Otherwise just returns the data. Decoding is as follows (with schema types listed in parentheses):

  • object → dict (obj)

  • array → list (mixed or list)

  • number → as-is (num)

  • boolean → as-is (bool)

  • string → string (str)

  • null → supplied null string or the default "null" (num)

Note that an object decoded into a dict will return the keys in the same order as the original string.

    . json::decode {[1, 2]}
    {1 2}
    . json::decode -schema {[1, 2]}
    {1 2} {list num}
    . json::decode -schema {{"a":1, "b":2}}
    {a 1 b 2} {obj a num b num}
    . json::decode -schema {[1, 2, {a:"b", c:false}, "hello"]}
    {1 2 {a b c false} hello} {mixed num num {obj a str c bool} str}
    . json::decode -index {["foo", "bar"]}
    {0 foo 1 bar}

BUILT-IN VARIABLES

The following global variables are created automatically by the Tcl library.

env

This variable is set by Jim as an array whose elements are the environment variables for the process. Reading an element will return the value of the corresponding environment variable. This array is initialised at startup from the env command. It may be modified and will affect the environment passed to commands invoked with exec.

platform_tcl

This variable is set by Jim as an array containing information about the platform on which Jim was built. Currently this includes os and platform.

auto_path

This variable contains a list of paths to search for packages. It defaults to a location based on where jim is installed (e.g. /usr/local/lib/jim), but may be changed by jimsh or the embedding application. Note that jimsh will consider the environment variable $JIMLIB to be a list of colon-separated list of paths to add to auto_path.

errorCode

This variable holds the value of the -errorcode return option set by the most recent error that occurred in this interpreter. This list value represents additional information about the error in a form that is easy to process with programs. The first element of the list identifies a general class of errors, and determines the format of the rest of the list. The following formats for -errorcode return options are used by the Tcl core; individual applications may define additional formats. Currently only exec sets this variable. Otherwise it will be NONE.

The following global variables are set by jimsh.

tcl_interactive

This variable is set to 1 if jimsh is started in interactive mode or 0 otherwise.

tcl_platform

This variable is set by Jim as an array containing information about the platform upon which Jim was built. The following is an example of the contents of this array.

    tcl_platform(byteOrder)     = littleEndian
    tcl_platform(engine)        = Jim
    tcl_platform(os)            = Darwin
    tcl_platform(platform)      = unix
    tcl_platform(pointerSize)   = 8
    tcl_platform(threaded)      = 0
    tcl_platform(wordSize)      = 8
    tcl_platform(pathSeparator) = :
argv0

If jimsh is invoked to run a script, this variable contains the name of the script.

argv

If jimsh is invoked to run a script, this variable contains a list of any arguments supplied to the script.

argc

If jimsh is invoked to run a script, this variable contains the number of arguments supplied to the script.

jim::argv0

The value of argv[0] when jimsh was invoked.

The following variables have special meaning to Jim Tcl:

jim::defer

If this variable is set, it is considered to be a list of scripts to evaluate when the current proc exits (local variables), or the interpreter exits (global variable). See defer.

history::multiline

If this variable is set to "1", interactive line editing operates in multiline mode. That is, long lines will wrap across multiple lines rather than scrolling within a single line.

CHANGES IN PREVIOUS RELEASES

In v0.74

  1. Numbers with leading zeros are treated as decimal, not octal

  2. Add aio isatty

  3. Add LFS (64 bit) support for aio seek, aio tell, aio copyto, file copy

  4. string compare and string equal now support -length

  5. glob now supports -directory

In v0.73

  1. Built-in regexp now support non-capturing parentheses: (?:…)

  2. Add string replace

  3. Add string totitle

  4. Add info statics

  5. Add build-jim-ext for easy separate building of loadable modules (extensions)

  6. local now works with any command, not just procs

  7. Add info alias to access the target of an alias

  8. UTF-8 encoding past the basic multilingual plane (BMP) is supported

  9. Add tcl::prefix

  10. Add history

  11. Most extensions are now enabled by default

  12. Add support for namespaces and the namespace command

  13. Add apply

In v0.72

  1. procs now allow args and optional parameters in any position

  2. Add Tcl-compatible expr functions, rand(), srand() and pow()

  3. Add support for the -force option to file delete

  4. Better diagnostics when source fails to load a script with a missing quote or bracket

  5. New tcl_platform(pathSeparator)

  6. Add support settings the modification time with file mtime

  7. exec is now fully supported on win32 (mingw32)

  8. file join, pwd, glob etc. now work for mingw32

  9. Line editing is now supported for the win32 console (mingw32)

  10. Add aio listen command

In v0.71

  1. Allow args to be renamed in procs

  2. Add $(…) shorthand syntax for expressions

  3. Add automatic reference variables in procs with &var syntax

  4. Support jimsh --version

  5. Additional variables in tcl_platform()

  6. local procs now push existing commands and upcall can call them

  7. Add loop command (TclX compatible)

  8. Add aio buffering command

  9. info complete can now return the missing character

  10. binary format and binary scan are now (optionally) supported

  11. Add string byterange

  12. Built-in regexp now support non-greedy repetition (*?, +?, ??)

In v0.70

  1. platform_tcl() settings are now automatically determined

  2. Add aio $handle filename

  3. Add info channels

  4. The bio extension is gone. Now aio supports copyto.

  5. Add exists command

  6. Add the pure-Tcl oo extension

  7. The exec command now only uses vfork(), not fork()

  8. Unit test framework is less verbose and more Tcl-compatible

  9. Optional UTF-8 support

  10. Optional built-in regexp engine for better Tcl compatibility and UTF-8 support

  11. Command line editing in interactive mode, e.g. jimsh

In v0.63

  1. source now checks that a script is complete (.i.e. not missing a brace)

  2. info complete now uses the real parser and so is 100% accurate

  3. Better access to live stack frames with info frame, stacktrace and stackdump

  4. tailcall no longer loses stack trace information

  5. Add alias and curry

  6. lambda, alias and curry are implemented via tailcall for efficiency

  7. local allows procedures to be deleted automatically at the end of the current procedure

  8. udp sockets are now supported for both clients and servers.

  9. vfork-based exec is now working correctly

  10. Add file tempfile

  11. Add socket pipe

  12. Enhance try … on … finally to be more Tcl 8.6 compatible

  13. It is now possible to return from within try

  14. IPv6 support is now included

  15. Add string is

  16. Event handlers works better if an error occurs. eof handler has been removed.

  17. exec now sets $::errorCode, and catch sets opts(-errorcode) for exit status

  18. Command pipelines via open "|…" are now supported

  19. pid can now return pids of a command pipeline

  20. Add info references

  21. Add support for after 'ms, 'after idle, after info, update

  22. exec now sets environment based on $::env

  23. Add dict keys

  24. Add support for lsort -index

In v0.62

  1. Add support to exec for >&, >>&, |&, 2>@1

  2. Fix exec error messages when special token (e.g. >) is the last token

  3. Fix subst handling of backslash escapes.

  4. Allow abbreviated options for subst

  5. Add support for return, break, continue in subst

  6. Many expr bug fixes

  7. Add support for functions in expr (e.g. int(), abs()), and also in, ni list operations

  8. The variable name argument to regsub is now optional

  9. Add support for unset -nocomplain

  10. Add support for list commands: lassign, lrepeat

  11. Fully-functional lsearch is now implemented

  12. Add info nameofexecutable and info returncodes

  13. Allow catch to determine what return codes are caught

  14. Allow incr to increment an unset variable by first setting to 0

  15. Allow args and optional arguments to the left or required arguments in proc

  16. Add file copy

  17. Add try … finally command

LICENCE

Copyright 2005 Salvatore Sanfilippo <antirez@invece.org>
Copyright 2005 Clemens Hintze <c.hintze@gmx.net>
Copyright 2005 patthoyts - Pat Thoyts <patthoyts@users.sf.net>
Copyright 2008 oharboe - Oyvind Harboe - oyvind.harboe@zylin.com
Copyright 2008 Andrew Lunn <andrew@lunn.ch>
Copyright 2008 Duane Ellis <openocd@duaneellis.com>
Copyright 2008 Uwe Klein <uklein@klein-messgeraete.de>
Copyright 2009 Steve Bennett <steveb@workware.net.au>
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
   notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above
   copyright notice, this list of conditions and the following
   disclaimer in the documentation and/or other materials
   provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE JIM TCL PROJECT ``AS IS'' AND ANY
EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
JIM TCL PROJECT OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
The views and conclusions contained in the software and documentation
are those of the authors and should not be interpreted as representing
official policies, either expressed or implied, of the Jim Tcl Project.