pam_systemd registers user sessions with 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 was 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 systemd scope unit is created for the session. If this is the
first concurrent session of the user, an implicit slice below
user.slice is automatically created and the scope placed into it.
An instance of the system service user@.service, which runs the
systemd user manager instance, is started.
On logout, this module ensures the following:
1. If enabled in logind.conf(5), all processes of the session are
terminated. If the last concurrent session of a user ends, the
user's systemd instance will be terminated too, and so will the
user's slice unit.
2. If the last concurrent session of a user ends, the $XDG_RUNTIME_DIR
directory and all its contents are removed, too.
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 string argument which sets the session class. The
XDG_SESSION_CLASS environmental variable takes precedence. One of
"user", "greeter", "lock-screen" or "background". See
sd_session_get_class(3) for details about the session class.
Takes a string argument which sets the session type. The
XDG_SESSION_TYPE environmental variable takes precedence. One of
"unspecified", "tty", "x11", "wayland" or "mir". See
sd_session_get_type(3) for details about the session type.
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 the user's 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
AF_UNIX sockets, FIFOs, PID files and similar. It is guaranteed
that this directory is local and offers the greatest possible file
system feature set the operating system provides. For further
details, see the XDG Base Directory Specification.
The following environment variables are read by the module and may be
used by the PAM service to pass metadata to the module:
The session type. This may be used instead of session= on the
module parameter line, and is usually preferred.
The session class. This may be used instead of class= on the module
parameter line, and is usually preferred.
A single, short identifier string for the desktop environment. This
may be used to indicate the session desktop used, where this
applies and if this information is available. For example: "GNOME",
or "KDE". It is recommended to use the same identifiers and
capitalization as for $XDG_CURRENT_DESKTOP, as defined by the
Desktop Entry Specification. (However, note that
$XDG_SESSION_DESKTOP only takes a single item, and not a
colon-separated list like $XDG_CURRENT_DESKTOP.) See
sd_session_get_desktop(3) for more details.
The seat name the session shall be registered for, if any.
The VT number the session shall be registered for, if any. (Only
applies to seats with a VT available, such as "seat0")
auth required pam_unix.so
1. XDG Base Directory Specification
2. Desktop Entry Specification
systemd 229 PAM_SYSTEMD(8)
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