xss

xss is a suite of X screensaver utilities. You can use shell scripts to glue the tools together to build your own screen saver and/or locker. You can use any xscreensaver hack instead of the built-in magic hack, or you can use xlock if you prefer.

The programs

xss uses the decades-old MIT-SCREEN-SAVER extension to launch a program when the X server turns on the built-in screen saver. Unlike xautolock, xss blocks until the X server says it's time to do something.

xsswin makes a full-screen black window and runs some other program, passing along the window ID in the environment ($XSS_WINDOW) and possibly as an argument (XSS_WINDOW in argv is replaced with the ID).

xkeygrab grabs the keyboard and mouse, and echoes all typed lines to stdout.

xcursorpos prints out the x and y coordinates of the cursor.

xbell sounds the X server's bell.

magic is a reimplementation of the "magic" screen saver from After Dark. It might look weird at 8bpp.

Examples

Tell the X server to launch the screen saver after 90 seconds idle:

$ xset s 90

Run like xautolock:

$ xss xlock -mode qix &

Just run a screen saver, don't lock

$ xss -w /usr/lib/xscreensaver/deco -window-id XSS_WINDOW &

Launch a program called "screenlock" when you're idle:

$ xss screenlock &

An simple "screenlock" script:

#! /bin/sh

xsswin magic XSS_WINDOW & pid=$!
xkeygrab | (while read l; do [ "$l" != "secret" ] && break; done)
kill $pid

A more complex "screenlock" script which locks the screen awaiting a pass phrase with the right md5 checksum. After 4 seconds of being locked, it pauses mpd (iff it was playing). When the screen is unlocked, mpd is resumed (iff it was playing beforehand). The script won't lock if the cursor's at the top of the screen.

#! /bin/sh

xcursorpos | (read x y; [ $y -lt 20 ]) && exit 0
mpc | fgrep -q '[playing]' && playing=1
xsswin magic XSS_WINDOW 2>/dev/null & xsswin=$!
(sleep 4; [ $playing ] && kill -0 $xsswin 2>/dev/null && mpc --no-status pause) &
xkeygrab | (
    while read l; do
        md5s=$(echo -n $l | md5sum | cut -d\  -f1)
        if [ $md5s = 'a37c87558d98e9fe0484e09070268be1' ]; then
            break
        fi
        xbell
    done
    )
kill $xsswin
[ $playing ] && mpc --no-status play

History

AIX apparently had something also called xss which did almost exactly what mine does, but with command-line options. magic is similar to the qix hack from xscreensaver and xlock. I'm not aware of anything else like the rest of the programs, which is why I wrote them.

I lifted some code from beforelight from the X11 distribution, and from slock from suckless.org. Both have a BSD/X11-like license.

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Neale Pickett neale@woozle.org