How can I run a shell script as a daemon under Redhat?

I’ve got a shell script, which is essentially a one liner with some logging, which I’m trying to run this from an init script. I’m using the daemon function inside of /etc/init.d/functions to run it, as Redhat does not appear to have start-stop-daemon available. When I call the init script (/etc/init.d/script start) it stays in the foreground, rather than completing and leaving the process running. What’s the proper way for me to get this script daemonized?

Script to be run:

# conf file where variables are defined
. /etc/script.conf

echo "Starting..." | logger -i
echo "Monitoring $LOG_LOCATION." | logger -i
echo "Sending to $MONITOR_HOST:$MONITOR_PORT." | logger -i

tail -n 1 -F $LOG_LOCATION |
grep WARN --line-buffered  |
/usr/bin/nc -vv $MONITOR_HOST $MONITOR_PORT 2>&1 |
logger -i

init script:

#!/bin/bash


# Source Defaults
. /etc/default/script

# Source init functions
. /etc/init.d/functions

prog=/usr/local/bin/script.sh

[ -f /etc/script.conf ] || exit 1

RETVAL=0

start()
{
    # Quit if disabled
    if ! $ENABLED; then
            echo "Service Disabled in /etc/default/script"
            exit 1
    fi

    echo "Starting $prog"

    daemon $prog

    RETVAL=$?

    return $RETVAL
}

stop ()
{
    echo -n $"Stopping $prog: "
    killproc $prog

    RETVAL=$?

    return $RETVAL
}

reload()
{
    echo "Reload command is not implemented for this service."
    return $RETVAL
}

restart()
{
    stop
    start
}

condrestart()
{
    echo "Not Implemented."
}

# See how we were called.
case "$1" in
    start)
        start
        ;;
    stop)
        stop
        ;;
    status)
        status $prog
        ;;
    restart)
        restart
        ;;
    reload)
        reload
        ;;
    condrestart)
        condrestart
        ;;
    *)
        echo $"Usage: $0 {start|stop|status|restart|condrestart|reload}"
        RETVAL=1
esac

Last ~20 lines of execution with bash -vx:

+ case "$1" in
+ start
+ true
+ echo 'Starting /usr/local/bin/script.sh'
Starting /usr/local/bin/script.sh
+ daemon /usr/local/bin/script.sh
+ local gotbase= force=
+ local base= user= nice= bg= pid=
+ nicelevel=0
+ '[' /usr/local/bin/script.sh '!=' /usr/local/bin/script.sh ']'
+ '[' -z '' ']'
+ base=script.sh
+ '[' -f /var/run/script.sh.pid ']'
+ '[' -n '' -a -z '' ']'
+ ulimit -S -c 0
+ '[' -n '' ']'
+ '[' color = verbose -a -z '' ']'
+ '[' -z '' ']'
+ initlog -q -c /usr/local/bin/script.sh

Answer

I found a script at http://www.linuxforums.org/forum/programming-scripting/190279-daemon-etc-init-d-functions-does-not-return-launching-process.html#post897522 which I was able to modify to suit my needs. It manually tracks the PID and creates a PID file using pidof. I ended up having to modify this to use pgrep as pidof was unable to see the PID of my script. After that modification, it worked fine. *Note, pgrep seems to only work if the full script name is under 15 characters long

Here’s what I ended up with:

#!/bin/bash
#
# 
#
# Start on runlevels 3, 4 and 5. Start late, kill early.
# chkconfig: 345 95 05
#
#
#!/bin/bash

# absolute path to executable binary
progpath='/usr/local/bin/script.sh'

# arguments to script
opts=''

# binary program name
prog=$(basename $progpath)

# pid file
pidfile="/var/run/${prog}.pid"

# make sure full path to executable binary is found
! [ -x $progpath ] && echo "$progpath: executable not found" && exit 1

eval_cmd() {
  local rc=$1
  if [ $rc -eq 0 ]; then
    echo '[  OK  ]'
  else
    echo '[FAILED]'
  fi
  return $rc
}

start() {
  # see if running
  local pids=$(pgrep $prog)

  if [ -n "$pids" ]; then
    echo "$prog (pid $pids) is already running"
    return 0
  fi
  printf "%-50s%s" "Starting $prog: " ''
  $progpath $opts &

  # save pid to file if you want
  echo $! > $pidfile

  # check again if running
  pgrep $prog >/dev/null 2>&1
  eval_cmd $?
}

stop() {
  # see if running
  local pids=$(pgrep $prog)

  if [ -z "$pids" ]; then
    echo "$prog not running"
    return 0
  fi
  printf "%-50s%s" "Stopping $prog: " ''
  rm -f $pidfile
  kill -9 $pids
  eval_cmd $?
}

status() {
  # see if running
  local pids=$(pgrep $prog)

  if [ -n "$pids" ]; then
    echo "$prog (pid $pids) is running"
  else
    echo "$prog is stopped"
  fi
}

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

exit $?

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