Minecraft Init Script

#!/bin/bash
# /etc/init.d/minecraft
# Requires: bash, java7, curl, rsync, mcrcon
# Author: Tom Arnold <tom9729@gmail.com>
# Version: 2013.11.30

### BEGIN INIT INFO
# Provides:   minecraft
# Required-Start: $local_fs $remote_fs
# Required-Stop:  $local_fs $remote_fs
# Should-Start:   $network
# Should-Stop:    $network
# Default-Start:  2 3 4 5
# Default-Stop:   0 1 6
# Short-Description:    Minecraft server
# Description:    Starts the minecraft server
### END INIT INFO

minecraft_home="/opt/minecraft"
minecraft_user="minecraft"
minecraft_world="world"
minecraft_cmd="java -Xincgc -Xmx3072M -Xms3072M -server -jar minecraft_server.jar nogui"
minecraft_backup_max="3000"
minecraft_rcon_cmd="$minecraft_home/mcrcon -H localhost -P 25576 -p changeme -s"

minecraft_cmd_exec() {
    $minecraft_rcon_cmd "$*"
}

minecraft_say() {
    minecraft_cmd_exec "say $@"
}

minecraft_start() {
    if [ `minecraft_status` ]; then return; fi

    cd "${minecraft_home}"
    nohup $minecraft_cmd > /dev/null 2>&1 &
}

minecraft_stop() {
    if [ ! `minecraft_status` ]; then return; fi

    cd "$minecraft_home"

    ## Save world.
    minecraft_cmd_exec "save-all"
    minecraft_cmd_exec "save-off"
    sleep 1
    sync

    ## Kill minecraft.
    kill -9 `minecraft_status`
    sleep 1
}

minecraft_restart() {
    minecraft_stop
    minecraft_start
}

minecraft_backup() {
    cd "${minecraft_home}"

    logger "Starting backup."

    ## List & count existing backups.
    local backup_list=`mktemp`
    ls backup | grep "${minecraft_world}-" > "$backup_list"
    local backup_count=`wc -l "$backup_list" | cut -d " " -f 1`
    local backup_delta=$(($backup_count - $minecraft_backup_max))

    ## Do we have more backups than we want?
    if [ "$backup_delta" -gt "0" ];
    then
    ## Delete old backups.
    logger "Purging $backup_delta old backups."
    head -$backup_delta "$backup_list" | xargs -I {} rm -rf "backup/{}"
    fi

    ## Cleanup.
    rm "$backup_list"

    ## Disable save to prevent corruption.
    minecraft_cmd_exec "save-all"
    minecraft_cmd_exec "save-off"
    sleep 1
    sync

    backup="${minecraft_world}-`date +%Y.%m.%d-%H.%M.%S`"
    prev_backup=`ls backup | tail -n 1`

    logger "Backing up world (backup/$backup)."

    if [ -z "${prev_backup}" ]
    then
    ## Make a baseline.
        cp -a "${minecraft_world}" "backup/${backup}"
    else
        ## Incremental backups using hardlinks and rsync.
        rsync -a --delete --link-dest="${minecraft_home}/backup/${prev_backup}" "${minecraft_world}" "backup/${backup}"
    fi

    ## Make a symbolic link to the latest backup.
    rm -f backup/latest
    ln -s "${minecraft_home}/backup/${backup}" backup/latest

    ## Enable save.
    minecraft_cmd_exec "save-on"

    logger "Finished backup."
}

minecraft_proc_list() {
    local proc_list=`mktemp`
    ps -u "$minecraft_user" -o pid,cmd > "$proc_list"
    echo "$proc_list"
}

minecraft_status() {
    local proc_list=`minecraft_proc_list`
    grep "java .* minecraft_server.jar" "$proc_list" | sed -e 's/^ *\([0-9]*\) .*$/\1/'
    rm "$proc_list"
}

minecraft_update() {
    cd ${minecraft_home}

    ## Try to figure out URL for latest release.
    local version_url="https://s3.amazonaws.com/Minecraft.Download/versions/versions.json"
    local version=`curl -s "$version_url" | grep '"release"\s*:' | sed -e 's/^.*:.*\"\(.*\)\".*$/\1/'`
    local release="minecraft_server.$version.jar"
    local release_url="https://s3.amazonaws.com/Minecraft.Download/versions/$version/$release"

    ## Check if we already have a server like that.
    if [ -e "$release" ];
    then
    ## Already at latest.
    return 0
    fi

    ## Download server JAR.
    echo "Getting latest release: $release"
    curl -s "$release_url" -o "$release"

    ## Shutdown server for update.
    minecraft_say "Server going down for update."
    minecraft_stop

    ## Point softlink at new release.
    rm minecraft_server.jar
    ln -s "$release" minecraft_server.jar

    ## Bring server back up.
    minecraft_start
}

minecraft_main() {
    ## Make sure that this script is run as minecraft_user.
    case `whoami` in
        ## Escape if we are minecraft_user.
    ${minecraft_user});;
        ## Relaunch as appropriate user.
    root)
        su ${minecraft_user} $0 $@
        exit $?
        ;;
        ## Not minecraft_user and can't su, so die.
    *)
        echo "fatal: must be run as (root, ${minecraft_user})" 1>&2
        exit 1
        ;;
    esac

    local cmd="$1"
    shift

    case "$cmd" in
    start|stop|restart|backup|update|status|say)
        ;;
    *)
        echo "Usage: $0 {start|stop|restart|backup|update|status|say} [...]" 1>&2
        return 1
        ;;
    esac

    minecraft_$cmd $@
}

minecraft_main $@