DOKK / manpages / debian 13 / libpam-runtime / pam_umask.8.en
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(7)

pam_umask was written by Thorsten Kukuk <kukuk@thkukuk.de>.

06/29/2025 Linux-PAM