How to make my init.d script change users

Question

I have this script which I would like to switch to the user "terraria" before starting the daemon. I can't figure out how to do it. My research brings me to bash scripts using su my_user -c, but I don't think that works in this case.

#!/bin/bash
# Terraria daemon
# chkconfig: 345 20 80
# description: Terraria Server
# processname: TerrariaServer.exe

DAEMON_PATH="/usr/Terraria"

DAEMON=TerrariaServer.exe
DAEMONOPTS="-world This_Land.wld -port 7777 "

NAME=TerrariaServer
DESC="Terraria Server"
PIDFILE=/var/run/TerrariaServer.pid
SCRIPTNAME=/etc/init.d/Terraria-Server

case "$1" in
start)
    printf "%-50s" "Starting $NAME..."
    cd $DAEMON_PATH
    PID=`mono $DAEMON $DAEMONOPTS > /dev/null 2>&1 & echo $!`
    #echo "Saving PID" $PID " to " $PIDFILE
        if [ -z $PID ]; then
            printf "%s\n" "Fail"
        else
            echo $PID > $PIDFILE
            printf "%s\n" "Ok"
        fi
;;
status)
        printf "%-50s" "Checking $NAME..."
        if [ -f $PIDFILE ]; then
            PID=`cat $PIDFILE`
            if [ -z "`ps axf | grep ${PID} | grep -v grep`" ]; then
                printf "%s\n" "Process dead but pidfile exists"
            else
                echo "Running"
            fi
        else
            printf "%s\n" "Service not running"
        fi
;;
stop)
        printf "%-50s" "Stopping $NAME"
            PID=`cat $PIDFILE`
            cd $DAEMON_PATH
        if [ -f $PIDFILE ]; then
            kill -HUP $PID
            printf "%s\n" "Ok"
            rm -f $PIDFILE
        else
            printf "%s\n" "pidfile not found"
        fi
;;

restart)
    $0 stop
    $0 start
;;

*)
        echo "Usage: $0 {status|start|stop|restart}"
        exit 1
esac

Answer 1

Check out the following link for the 'DJB' way of starting up processes as other users: http://thedjbway.b0llix.net/daemontools/uidgid.html

Also, see: How to run a command as a specific user in an init script?