pam_shells 8 Linux-PAM Manual pam_shells PAM module to check for valid login shell pam_shells.so pam_shells is a PAM module that only allows access to the system if the users shell is listed in /etc/shells. It also checks if /etc/shells is a plain file and not world writable. This module does not recognise any options. The auth and account module types are provided. PAM_AUTH_ERR Access to the system was denied. PAM_SUCCESS The users login shell was listed as valid shell in /etc/shells. PAM_SERVICE_ERR The module was not able to get the name of the user. auth required pam_shells.so shells5 , pam.conf5 , pam.d5 , pam8 pam_shells was written by Erik Troan <ewt@redhat.com>.