Minecraft server init script for Ubuntu/Debian

#!/bin/bash
################################################################################

#  This program is free software; you can redistribute it and/or modify it
#  under the terms of the GNU General Public License as published by the
#  Free Software Foundation; either version 2 of the License, or (at
#  your option) any later version.
#
#  This program is distributed in the hope that it will be useful, but
#  WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
#  General Public License for more details.
#
#  You should have received a copy of the GNU General Public License
#  along with this program; if not, write to the Free Software Foundation,
#  Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA

# Unless you change the below variables, this script assumes:
#  * Only one instance of minecraft is being run
#  * minecraft is installed in /usr/local/minecraft/
#  * The Linux user "mc" exists
#  * The Linux user "mc" owns /usr/local/minecraft/

################################################################################
. /lib/lsb/init-functions

##### You can change these variables #####
MC_PATH=/usr/local/minecraft;
MC_USER=mc;
MEMALOC=768;
MC_JAR=Minecraft_Mod.jar;   # minecraft_server.jar for vanilla, Minecraft_Mod.jar for hey0's mod
MC_LOCK=server.log.lck;
SCREEN_NAME=minecraft;
ID=`which id`;
KILL=`which kill`;
##### Don't change anything below here #####

start_minecraft() {
    log_action_begin_msg "Starting minecraft-server"

    # Make sure old minecraft isn't running because they fight for same ip:port
    if [ -f $MC_PATH/$MC_LOCK ]; then
        log_action_end_msg 1    # Fail
        log_failure_msg "Lock file exists. (Is minecraft-server already running?)"
        return
    fi

    # Check for existing screen session
    if [ ! "`screen -ls | grep $SCREEN_NAME | wc -l`" == "0" ]; then
        log_action_end_msg 1    # Fail
        log_failure_msg "Screen session exists. (Is minecraft-server already running?)"
        return
    fi

    # Allow full core dumps for debugging purposes
    ulimit -c unlimited

    # Run as correct user
    if [ "`$ID -u`" == "0" ]; then
        su $MC_USER -c "cd $MC_PATH; screen -m -d -S $SCREEN_NAME java -Xms${MEMALOC}M -Xmx${MEMALOC}M -Djava.net.preferIPv4Stack=true -jar $MC_JAR nogui"
    else
        cd $MC_PATH; screen -m -d -S $SCREEN_NAME java -Xms${MEMALOC}M -Xmx${MEMALOC}M -Djava.net.preferIPv4Stack=true -jar $MC_JAR nogui
    fi
    log_action_end_msg $?
}

stop_minecraft() {

    log_action_begin_msg "Stopping minecraft-server (nicely)"
    # Verify session exists
    if [ "`screen -ls | grep $SCREEN_NAME | wc -l`" == "0" ]; then
        log_action_end_msg 1    # Fail
        log_failure_msg "Screen session not found. (Is minecraft-server running?)"
        if [ ! "$FORCE" == "TRUE" ]; then
            return
        fi
    else    # Screen reports a session..
        SCREEN_PID=`screen -ls | grep $SCREEN_NAME | cut -f2 | cut -d. -f1`;
        screen -S $SCREEN_NAME -p 0 -X stuff $'say Shutdown requested by console.\n' &>/dev/null
        screen -S $SCREEN_NAME -p 0 -X stuff $'save-all\n' &>/dev/null; sleep 5
        screen -S $SCREEN_NAME -p 0 -X stuff $'stop\n' &>/dev/null; RET=$?; sleep 2
        log_action_end_msg $RET
        if [ ! "$FORCE" == "TRUE" ]; then
            return
        fi
    fi

    if [ "$FORCE" == "TRUE" ]; then
        log_action_begin_msg "Stopping minecraft-server (forced)"
        # Use the PID returned by screen, if possible
        if [ -h /proc/${SCREEN_PID-UNSET}/exe ]; then
            $KILL -TERM $SCREEN_PID; sleep 1    # Try to be nice
            $KILL -KILL $SCREEN_PID &>/dev/null # Use more force
        fi
        # Brute force killing
        OTHER_PIDS=`ps ax | grep java | grep $MC_JAR | grep -v grep | cut -d' ' -f2`
        if [ -n "$OTHER_PIDS" ]; then
            $KILL -TERM $OTHER_PIDS; sleep 1    # Try to be nice
            $KILL -KILL $OTHER_PIDS &>/dev/null # Use more force
        fi

        # Remove the lock file
        if [ -f $MC_PATH/$MC_LOCK ]; then
            rm -f $MC_PATH/$MC_LOCK
        fi
        log_action_end_msg 0    # Success
    fi

}


if [ ${2-UNSET} == "force" ]; then
    FORCE="TRUE";
fi
case "$1" in

    start)
        start_minecraft
        ;;
    stop)
        stop_minecraft
        ;;
    restart)
        stop_minecraft
        log_action_begin_msg "Sleeping"
        sleep 2
        log_action_end_msg $?
        start_minecraft
        ;;
    *)
        echo "usage: $0 {start|stop [force]|restart [force]}"
esac