diff options
Diffstat (limited to 'chronyd.8.in')
| -rw-r--r-- | chronyd.8.in | 48 |
1 files changed, 26 insertions, 22 deletions
diff --git a/chronyd.8.in b/chronyd.8.in index bafe85e..22edec7 100644 --- a/chronyd.8.in +++ b/chronyd.8.in @@ -1,4 +1,4 @@ -.TH CHRONYD 8 "June 2015" "chrony 2.1.1" "System Administration" +.TH CHRONYD 8 "October 2015" "chrony 2.2" "System Administration" .SH NAME chronyd \- chrony background daemon @@ -40,9 +40,11 @@ A summary of the options supported by \fBchronyd\fR is included below. .TP \fB\-P\fR \fIpriority\fR -This option will select the SCHED_FIFO real-time scheduler at the specified -priority (which must be between 0 and 100). This mode is supported only on -Linux. +On Linux, this option will select the SCHED_FIFO real-time scheduler at the +specified priority (which must be between 0 and 100). On Mac OS X, this +option must have either a value of 0 (the default) to disable the thread +time constraint policy or 1 for the policy to be enabled. Other systems do not +support this option. .TP .B \-m This option will lock chronyd into RAM so that it will never be paged out. @@ -67,10 +69,9 @@ This option will reload sample histories for each of the servers being used. These histories are created by using the \fIdump\fR command in \fIchronyc\fR, or by setting the \fIdumponexit\fR directive in the configuration file. This option is useful if you want to stop and restart \fBchronyd\fR briefly for any -reason, e.g. to install a new version. However, it only makes sense on +reason, e.g. to install a new version. However, it should be used only on systems where the kernel can maintain clock compensation whilst not under -\fBchronyd\fR's control. The only version where this happens so far is Linux. -On other systems this option should not be used. +\fBchronyd\fR's control (i.e. Linux, FreeBSD, NetBSD and Solaris). .TP .B \-R When this option is used, the \fIinitstepslew\fR directive and the @@ -79,13 +80,9 @@ option is useful when restarting \fBchronyd\fR and can be used in conjunction with the \fB-r\fR option. .TP .B \-s -This option will set the system clock from the computer's real-time -clock. This is analogous to supplying the \fI-s\fR flag to the -\fI/sbin/hwclock\fR program during the Linux boot sequence. - -Support for real-time clocks is limited at present - the criteria -are described in the section on the \fIrtcfile\fR directive in the -documentation supplied with the distribution. +This option will set the system clock from the computer's real-time clock or +to the last modification time of the file specified by the \fIdriftfile\fR +directive. Real-time clocks are supported only on Linux. If used in conjunction with the \fB-r\fR flag, \fBchronyd\fR will attempt to preserve the old samples after setting the system clock from @@ -96,16 +93,23 @@ not in use. For this to work well, it relies on \fBchronyd\fR having been able to determine accurate statistics for the difference between the RTC and system clock last time the computer was on. -If \fBchronyd\fR doesn't support the RTC on your computer or there is no RTC -installed, the system clock will be set with this option forward to the time of -the last modification of the drift file (specified by the \fIdriftfile\fR -directive) to restore the system time at which \fBchronyd\fR was previously -stopped. +If the last modification time of the drift file is later than the current time +and the RTC time, the system time will be set to it to restore the time when +\fBchronyd\fR was previously stopped. This is useful on computers that have no +RTC or the RTC is broken (e.g. it has no battery). .TP \fB\-u\fR \fIuser\fR -This option sets the name of the user to which will \fBchronyd\fR switch to -drop root privileges if compiled with Linux capabilities support (default -\fB@DEFAULT_USER@\fR). +This option sets the name of the system user to which \fBchronyd\fR will switch +after start in order to drop root privileges. It overrides the \fBuser\fR +directive (default \fB@DEFAULT_USER@\fR). It may be set to a non-root user +only when \fBchronyd\fR is compiled with support for Linux capabilities +(libcap) or on NetBSD with the \fB/dev/clockctl\fR device. +.TP +\fB\-F\fR \fIlevel\fR +This option configures a system call filter when \fBchronyd\fR is compiled with +support for the Linux secure computing (seccomp) facility. In level 1 the +process is killed when a forbidden system call is made, in level -1 the SYSSIG +signal is thrown instead and in level 0 the filter is disabled (default 0). .TP .B \-q When run in this mode, chronyd will set the system clock once |