pam_motd.so [
motd=/path/filename
] [
motd_dir=/path/dirname.d
]
pam_motd is a PAM module that can be used to display arbitrary motd (message of the day) files after a successful login. By default, pam_motd shows files in the following locations:
/etc/motd |
/run/motd |
/usr/lib/motd |
/etc/motd.d/ |
/run/motd.d/ |
/usr/lib/motd.d/ |
Each message size is limited to 64KB.
If /etc/motd does not exist,
then /run/motd is shown. If
/run/motd does not exist, then
/usr/lib/motd is shown.
Similar overriding behavior applies to the directories.
Files in /etc/motd.d/ override files
with the same name in /run/motd.d/ and
/usr/lib/motd.d/. Files in /run/motd.d/
override files with the same name in /usr/lib/motd.d/.
Files in the directories listed above are displayed in lexicographic order by name. Moreover, the files are filtered by reading them with the credentials of the target user authenticating on the system.
To silence a message,
a symbolic link with target /dev/null
may be placed in /etc/motd.d with
the same filename as the message to be silenced. Example:
Creating a symbolic link as follows silences /usr/lib/motd.d/my_motd.
ln -s /dev/null /etc/motd.d/my_motd
The MOTD_SHOWN=pam environment variable is set after showing the motd files, even when all of them were silenced using symbolic links.
The /path/filename file is displayed
as message of the day. Multiple paths to try can be
specified as a colon-separated list. By default this option
is set to /etc/motd:/run/motd:/usr/lib/motd.
The /path/dirname.d directory is scanned
and each file contained inside of it is displayed. Multiple
directories to scan can be specified as a colon-separated list.
By default this option is set to /etc/motd.d:/run/motd.d:/usr/lib/motd.d.
When no options are given, the default behavior applies for both options. Specifying either option (or both) will disable the default behavior for both options.
Not all relevant data or options could be obtained.
Memory buffer error.
This is the default return value of this module.
The suggested usage for /etc/pam.d/login is:
session optional pam_motd.so
To use a motd file from a different location:
session optional pam_motd.so motd=/elsewhere/motd
To use a motd file from elsewhere, along with a
corresponding .d directory:
session optional pam_motd.so motd=/elsewhere/motd motd_dir=/elsewhere/motd.d