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PAM_SYSTEMD(8)                    pam_systemd                   PAM_SYSTEMD(8)
NAME
       pam_systemd - Register user sessions in the systemd login manager
SYNOPSIS
       pam_systemd.so
DESCRIPTION
       pam_systemd registers user sessions with the systemd login manager
       systemd-logind.service(8), and hence the systemd control group
       hierarchy.
       On login, this module -- in conjunction with systemd-logind.service --
       ensures the following:
        1. If it does not exist yet, the user runtime directory /run/user/$UID
           is either created or mounted as new "tmpfs" file system with quota
           applied, and its ownership changed to the user that is logging in.
        2. The $XDG_SESSION_ID environment variable is initialized. If
           auditing is available and pam_loginuid.so was run before this
           module (which is highly recommended), the variable is initialized
           from the auditing session id (/proc/self/sessionid). Otherwise, an
           independent session counter is used.
        3. A new systemd scope unit is created for the session. If this is the
           first concurrent session of the user, an implicit per-user slice
           unit below user.slice is automatically created and the scope placed
           into it. An instance of the system service user@.service, which
           runs the systemd user manager instance, is started.
       On logout, this module ensures the following:
        1. If enabled in logind.conf(5) (KillUserProcesses=), all processes of
           the session are terminated. If the last concurrent session of a
           user ends, the user's systemd instance will be terminated too, and
           so will the user's slice unit.
        2. If the last concurrent session of a user ends, the user runtime
           directory /run/user/$UID 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.
OPTIONS
       The following options are understood:
       class=
           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.
       type=
           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.
       debug[=]
           Takes an optional boolean argument. If yes or without the argument,
           the module will log debugging information as it operates.
MODULE TYPES PROVIDED
       Only session is provided.
ENVIRONMENT
       The following environment variables are set for the processes of the
       user's session:
       $XDG_SESSION_ID
           A session identifier, suitable to be used in filenames. 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.
       $XDG_RUNTIME_DIR
           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[1].
           $XDG_RUNTIME_DIR is not set if the current user is not the original
           user of the session.
       The following environment variables are read by the module and may be
       used by the PAM service to pass metadata to the module:
       $XDG_SESSION_TYPE
           The session type. This may be used instead of session= on the
           module parameter line, and is usually preferred.
       $XDG_SESSION_CLASS
           The session class. This may be used instead of class= on the module
           parameter line, and is usually preferred.
       $XDG_SESSION_DESKTOP
           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[2]. (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.
       $XDG_SEAT
           The seat name the session shall be registered for, if any.
       $XDG_VTNR
           The VT number the session shall be registered for, if any. (Only
           applies to seats with a VT available, such as "seat0")
       If not set, pam_systemd will determine the values for $XDG_SEAT and
       $XDG_VTNR based on the $DISPLAY variable.
SESSION LIMITS
       PAM modules earlier in the stack, that is those that come before
       pam_systemd.so, can set session scope limits using the PAM context
       objects. The data for these objects is provided as NUL-terminated C
       strings and maps directly to the respective unit resource control
       directives. Note that these limits apply to individual sessions of the
       user, they do not apply to all user processes as a combined whole. In
       particular, the per-user user@.service unit instance, which runs the
       systemd --user manager process and its children, and is tracked outside
       of any session, being shared by all the user's sessions, is not covered
       by these limits.
       See systemd.resource-control(5) for more information about the
       resources. Also, see pam_set_data(3) for additional information about
       how to set the context objects.
       systemd.memory_max
           Sets unit MemoryMax=.
       systemd.tasks_max
           Sets unit TasksMax=.
       systemd.cpu_weight
           Sets unit CPUWeight=.
       systemd.io_weight
           Sets unit IOWeight=.
       Example data as can be provided from an another PAM module:
           pam_set_data(handle, "systemd.memory_max", (void *)"200M", cleanup);
           pam_set_data(handle, "systemd.tasks_max",  (void *)"50",   cleanup);
           pam_set_data(handle, "systemd.cpu_weight", (void *)"100",  cleanup);
           pam_set_data(handle, "systemd.io_weight",  (void *)"340",  cleanup);
EXAMPLE
           #%PAM-1.0
           auth       required     pam_unix.so
           auth       required     pam_nologin.so
           account    required     pam_unix.so
           password   required     pam_unix.so
           session    required     pam_unix.so
           session    required     pam_loginuid.so
           session    required     pam_systemd.so
SEE ALSO
       systemd(1), systemd-logind.service(8), logind.conf(5), loginctl(1),
       pam.conf(5), pam.d(5), pam(8), pam_loginuid(8), systemd.scope(5),
       systemd.slice(5), systemd.service(5)
NOTES
        1. XDG Base Directory Specification
           http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html
        2. Desktop Entry Specification
           http://standards.freedesktop.org/desktop-entry-spec/latest/
systemd 239                                                     PAM_SYSTEMD(8)