Shell script to emulate BOINC screensaver behavior

boincgfx.sh

#!/bin/sh
# This script shows random BOINC graphics application

# To run this script you must have the following software installed:
#  - Xephyr
#  - xinit
#  - some window manager (like ratpoison or dwm)

# BOINC_DIR = `/var/lib/boinc` for boinc>=7.10.2, `/var/lib/boinc-client` for older versions
# WINDOW_MANAGER = command to launch your preferred window manager (shold contain absolute path to the executable)
# SWITCH_TIME = time the script will wait before switching to another graphics application
# TRANSITION_TIME = time to wait before killing running screensaver after launching a new one
# DISP = fake Xephyr display name
BOINC_DIR=/var/lib/boinc
WINDOW_MANAGER=/usr/bin/ratpoison
SWITCH_TIME=300
TRANSITION_TIME=10
DISP=:2

trap "quit 0" INT # catch CTRL-C

# exit gracefully
quit() {
    echo "- Quitting..."
    exit_status=$1
    for pidfile in boincgfx xephyr; do
        old_pid=$(cat /tmp/$pidfile.pid 2>/dev/null)
        wait_then_kill "$old_pid" >/dev/null &
    done
    rm /tmp/boincgfx.pid /tmp/xephyr.pid 2>/dev/null
    exit "$exit_status"
}

# `wait_then_kill 3856 10`: waits 10 seconds and kills a process with PID 3856
# `wait_then_kill 3856`: kills a process with PID 3856 immediately
wait_then_kill() {
    pid=$1
    [ -z "$pid" ] && return
    sleep "$TRANSITION_TIME" 2>/dev/null

    echo -n "  * killing running graphics application (PID $pid) "
    while kill "$pid" 2>/dev/null; do
        echo -n ". "
        sleep 0.1
    done
    echo
}

# check whether graphics application has open windows
check_window() {
    sleep $TRANSITION_TIME

    DISPLAY=$DISP xdotool search --pid "$(cat /tmp/boincgfx.pid)" && return 0

    echo "  !! couldn't create window - leaving..."
    wait_then_kill "$(cat /tmp/boincgfx.pid)" 0
    return 1
}

show_screensaver() {
    random_gfx=$(find $BOINC_DIR/slots/* -name graphics_app | shuf -n 1)
    slot=$(dirname "$random_gfx")
    echo "- Found a slot with graphics: $slot"
    grep -q suspend "$slot/boinc_mmap_file" && {
        echo "  !! the app is suspended - leaving..."
        return
    }

    gfx_exec=$(cat "$random_gfx")
    gfx_exec=${gfx_exec#<soft_link>}
    gfx_exec=${gfx_exec%</soft_link>}

    if [ -f /tmp/boincgfx.pid ]; then
        old_pid=$(cat /tmp/boincgfx.pid)
        wait_then_kill "$old_pid" "$TRANSITION_TIME" &
        rm /tmp/boincgfx.pid
    fi

    cd "$slot" || return
    DISPLAY=$DISP $gfx_exec >/dev/null 2>&1 &
    echo $! > /tmp/boincgfx.pid
    echo "  * started new graphics application (PID $(cat /tmp/boincgfx.pid))"

    #check_window || return
    sleep $SWITCH_TIME
}

rm /tmp/xephyr.pid 2>/dev/null
startx "$WINDOW_MANAGER" -- /usr/bin/Xephyr $DISP -fullscreen >/dev/null 2>&1 &
echo $! > /tmp/xephyr.pid

sleep 5
if pgrep -F /tmp/xephyr.pid; then
    echo "- Started Xephyr server"
else
    echo "!! Xephyr server crashed"
    echo "!! Check WINDOW_MANAGER variable in the script"
    quit 1
fi

while true; do
    show_screensaver
    pgrep -F /tmp/xephyr.pid || quit 0
done

Installing dependencies

1. Ubuntu/Debian
   $ sudo apt-get install xserver-xephyr ratpoison
2. Fedora
   $ sudo dnf install xorg-x11-server-Xephyr ratpoison
3. Arch Linux
   # pacman -S xorg-server-xephyr ratpoison
4. Gentoo
   • emerge x11-base/xorg-server[xephyr] and x11-wm/ratpoison

Thank you!

Updated version can be found there:
https://sysrq.in/pub/distfiles/