xss-lock(1)

Name
xss-lock - use external locker as X screen saver

Synopsis
xss-lock [-n notify_cmd] [-s session ID] [--ignore-sleep] [-l] [-v|-q] [--] locker [arg] ...
xss-lock --help|--version

Description

xss-lock hooks up your favorite locker to the MIT screen saver extension for X and also to systemd's login manager.

xss-lock should be run in your xsession either by starting it in your .xsessionrc or by other session specific means (e.g. Window manager configuration). Note that xss-lock runs in the foreground (i.e. doesn't fork) and therefore you may need to run it in the background (for example by running with &).

The locker is executed in response to events from these two sources:

•   X signals when screen saver activation is forced or after a period of user inactivity (as set with xset s TIMEOUT). In the latter case, the notifier command, if specified, is executed first.

•   The login manager can also request that the session be locked; as a result of loginctl lock-sessions, for example. Additionally, xss-lock uses the inhibition logic to lock the screen before the system goes to sleep.

    xss-lock waits for the locker to exit -- or kills it when screen saver deactivation or session unlocking is forced -- so the command should not fork.

    Also, xss-lock manages the idle hint on the login session. The idle state of the session is directly linked to user activity as reported by X (except when the notifier runs before locking the screen). When all sessions are idle, the login manager can take action (such as suspending the system) after a preconfigured delay.

Options

-n cmd, --notifier=cmd
    Run cmd when the screen saver activates because of user inactivity. Shell-style quoting is supported. The notifier is killed with the signal SIGHUP when X signals user activity or with signal SIGTERM when the locker is started. The locker is started after the first screen saver cycle, as set with xset s TIMEOUT CYCLE. If the screen saver cycle time is 0, the notifier is not run and the locker is started immediately after timeout.

    This can be used to run a countdown or (on laptops) dim the screen before locking. For an example, see the script /usr/share/doc/xss-lock/dim-screen.sh.

    For an example on how to use the two different signals received by the notifier command, see the script /usr/share/doc/xss-lock/dim-screen2.sh.

-l, --transfer-sleep-lock
    Allow the locker process to inherit the file descriptor that represents the delay lock obtained from the login manager. The corresponding index will be made available in the environment variable $XSS_SLEEP_LOCK_FD; this will only be set if the reason for locking is that the system is preparing to go to sleep. The locker should close this file descriptor to indicate it is ready.

    Example scripts that wrap existing lockers are available as /usr/share/doc/xss-lock/transfer-sleep-lock-*.sh.

-s ID, --session=ID
    Use the session ID instead of the current session.

    Example: /usr/share/doc/xss-lock/xss-lock.service.

--ignore-sleep
    Do not lock on suspend/hibernate.

-q, --quiet
    Output only fatal errors.

-v, --verbose
    Output more messages.

-h, --help
    Print help message and exit.

--version
    Print version number and exit.

Signals

SIGHUP
    Upon receiving this signal, xss-lock resets the screen saver, but only if the screen is not currently locked (unlike xset s reset).

    This can be used in MPlayer's configuration as a workaround for MPlayer's failure to restart the screen saver timer when playback is paused:

        heartbeat-cmd="killall -HUP xss-lock"
        stop-xscreensaver=false

    Note: This is ineffective with mplayer2 (and mpv), because its heart keeps beating while playback is paused.

SIGINT/SIGTERM
    Upon receiving this signal, xss-lock exits after killing any running notifier or locker.

Notes

•   Some applications rely on the xdg-screensaver script from xdg-utils, which uses xset s off and xset s default to suspend and resume the screen saver, respectively. The latter resets the timeout and cycle to the server defaults (xset s on uses a hardcoded default instead), so this only works if you are happy with (or can control) the server settings.

    To fix the resume action in this script (or a copy in ~/bin preceding the original in $PATH), either replace on by your preferred timeout and cycle, or avoid hardcoded time values by patching the script to run a suspend loop as it does for other screen savers, using /usr/share/doc/xss-lock/xdg-screensaver.patch.

Examples

•   Use with xscreensaver via .xsessionrc (hence in the background):

        xscreensaver &
        xss-lock -- xscreensaver-command --lock &

•   Run xlock after ten minutes of inactivity:

        xset s 600
        xss-lock xlock +resetsaver

    Without +resetsaver, xlock forces a screen saver reset during startup, thereby telling xss-lock to immediately kill xlock again.

•   Dim the screen after three minutes of inactivity, lock the screen two minutes later using i3lock:

        xset s 180 120
        xss-lock -n dim-screen.sh -- i3lock -n

    Note: A script is provided to use i3lock's forking mode with the --transfer-sleep-lock option (see above).

See also

loginctl(1), xset(1), systemd-logind.service(8)

Author
Raymond Wagenmaker <raymondwagenmaker@gmail.com>