pam_systemd registers user sessions in the systemd login manager
systemd-logind.service(8), and hence the systemd control group
On login, this module ensures the following:
1. If it does not exist yet, the user runtime directory
/run/user/$USER is created and its ownership changed to the user
that is logging in.
2. The $XDG_SESSION_ID environment variable is initialized. If
auditing is available and pam_loginuid.so run before this module
(which is highly recommended), the variable is initialized from the
auditing session id (/proc/self/sessionid). Otherwise an
independent session counter is used.
3. A new control group /user/$USER/$XDG_SESSION_ID is created and the
login process moved into it.
On logout, this module ensures the following:
1. If $XDG_SESSION_ID is set and kill-session-processes=1 specified,
all remaining processes in the /user/$USER/$XDG_SESSION_ID control
group are killed and the control group is removed.
2. If the last subgroup of the /user/$USER control group was removed
the $XDG_RUNTIME_DIR directory and all its contents are removed,
If the system was not booted up with systemd as init system, this
module does nothing and immediately returns PAM_SUCCESS.
The following options are understood:
Takes a boolean argument. If true, all processes created by the
user during his session and from his session will be terminated
when he logs out from his session.
Takes a comma separated list of user names or numeric user ids as
argument. If this option is used the effect of the
kill-session-processes= options will apply only to the listed
users. If this option is not used the option applies to all local
users. Note that kill-exclude-users= takes precedence over this
list and is hence subtracted from the list specified here.
Takes a comma separated list of control group controllers in which
hierarchies the logged in processes will be reset to the root
Takes a string argument which sets the session class. The
XDG_SESSION_CLASS environmental variable takes precedence.
Takes a boolean argument. If yes, the module will log debugging
information as it operates.
Note that setting kill-session-processes=1 will break tools like
Note that kill-session-processes=1 is a stricter version of
KillUserProcesses=1 which may be configured system-wide in
logind.conf(5). The former kills processes of a session as soon as it
ends, the latter kills processes as soon as the last session of the
If the options are omitted they default to kill-session-processes=0,
kill-only-users=, kill-exclude-users=, controllers=,
MODULE TYPES PROVIDED
Only session is provided.
The following environment variables are set for the processes of the
A session identifier, suitable to be used in file names. The string
itself should be considered opaque, although often it is just the
audit session ID as reported by /proc/self/sessionid. Each ID will
be assigned only once during machine uptime. It may hence be used
to uniquely label files or other resources of this session.
Path to a user-private user-writable directory that is bound to the
user login time on the machine. It is automatically created the
first time a user logs in and removed on his final logout. If a
user logs in twice at the same time, both sessions will see the
same $XDG_RUNTIME_DIR and the same contents. If a user logs in
once, then logs out again, and logs in again, the directory
contents will have been lost in between, but applications should
not rely on this behavior and must be able to deal with stale
files. To store session-private data in this directory the user
should include the value of $XDG_SESSION_ID in the filename. This
directory shall be used for runtime file system objects such as
session required pam_systemd.so kill-session-processes=1
systemd(1), systemd-logind.service(8), logind.conf(5), loginctl(1),
pam.conf(5), pam.d(5), pam(8), pam_loginuid(8)
systemd 204 PAM_SYSTEMD(8)
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