pam_motd(8) — Linux manual page

PAM_MOTD(8)                 Linux-PAM Manual                 PAM_MOTD(8)

NAME

       pam_motd - Display the motd file

SYNOPSIS

       pam_motd.so [motd=/path/filename] [motd_dir=/path/dirname.d]

DESCRIPTION

       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.

OPTIONS

       motd=/path/filename
           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.

       motd_dir=/path/dirname.d
           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.

MODULE TYPES PROVIDED

       Only the session module type is provided.

RETURN VALUES

       PAM_ABORT
           Not all relevant data or options could be obtained.

       PAM_BUF_ERR
           Memory buffer error.

       PAM_IGNORE
           This is the default return value of this module.

EXAMPLES

       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

SEE ALSO

       motd(5), pam.conf(5), pam.d(5), pam(8)

AUTHOR

       pam_motd was written by Ben Collins <bcollins@debian.org>.

       The motd_dir= option was added by Allison Karlitskaya
       <allison.karlitskaya@redhat.com>.

COLOPHON

       This page is part of the linux-pam (Pluggable Authentication
       Modules for Linux) project.  Information about the project can be
       found at ⟨http://www.linux-pam.org/⟩.  If you have a bug report
       for this manual page, see ⟨//www.linux-pam.org/⟩.  This page was
       obtained from the project's upstream Git repository
       ⟨https://github.com/linux-pam/linux-pam.git⟩ on 2023-12-22.  (At
       that time, the date of the most recent commit that was found in
       the repository was 2023-12-18.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there
       is a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to
       man-pages@man7.org

Linux-PAM Manual               12/22/2023                    PAM_MOTD(8)

Pages that refer to this page: login(1), systemd.system-credentials(7)

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