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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | MODULE TYPES PROVIDED | RETURN VALUES | EXAMPLES | SEE ALSO | AUTHOR | COLOPHON |
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PAM_UMASK(8) Linux-PAM Manual PAM_UMASK(8)
pam_umask - PAM module to set the file mode creation mask
pam_umask.so [debug] [silent] [usergroups] [nousergroups]
[umask=mask]
pam_umask is a PAM module to set the file mode creation mask of
the current environment. The umask affects the default permissions
assigned to newly created files.
The PAM module tries to get the umask value from the following
places in the following order:
• umask= entry in the user's GECOS field (see below for details)
• umask= argument
• UMASK entry from /etc/login.defs
• UMASK= entry from /etc/default/login
The GECOS field is split on comma ',' characters. Entries must be
set in its 'other' (sub-)field (the 5th field within the GECOS
field), which could be done, for example, using chfn --other. In
addition to the umask= entry, the module also recognizes the pri=
entry, which sets the nice priority value for the session, and the
ulimit= entry, which sets the maximum size of files the processes
in the session can create.
debug
Print debug information.
silent
Don't print informative messages.
usergroups
If the user is not root and the username is the same as
primary group name, the umask group bits are set to be the
same as owner bits (examples: 022 -> 002, 077 -> 007).
nousergroups
This is the direct opposite of the usergroups option described
above, which can be useful in case pam_umask has been compiled
with usergroups enabled by default and you want to disable it
at runtime.
umask=mask
Sets the calling process's file mode creation mask (umask) to
mask & 0777. The value is interpreted as Octal.
Only the session type is provided.
PAM_SUCCESS
The new umask was set successfully.
PAM_BUF_ERR
Memory buffer error.
PAM_CONV_ERR
The conversation method supplied by the application failed to
obtain the username.
PAM_INCOMPLETE
The conversation method supplied by the application returned
PAM_CONV_AGAIN.
PAM_SERVICE_ERR
No username was given.
PAM_USER_UNKNOWN
User not known.
Add the following line to /etc/pam.d/login to set the user
specific umask at login:
session optional pam_umask.so umask=0022
pam.conf(5), pam.d(5), pam(8)
pam_umask was written by Thorsten Kukuk <kukuk@thkukuk.de>.
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 2026-01-16. (At
that time, the date of the most recent commit that was found in
the repository was 2026-01-12.) 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 01/16/2026 PAM_UMASK(8)
Pages that refer to this page: systemd.exec(5)
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HTML rendering created 2026-01-16 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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