Initscripts/Writing rc.d scripts

Related articles

• Arch Boot Process
• Daemon
• rc.conf

Warning: Arch only supports systemd. Arch's old initscripts package is obsolete and is no longer supported. All Arch users need to move to systemd.

Initscripts uses rc.d scripts to used to control the starting, stopping and restarting of daemons.

Guideline

• Source /etc/rc.conf, /etc/rc.d/functions, and optionally /etc/conf.d/DAEMON_NAME.
• Arguments and other daemon options should be placed in /etc/conf.d/DAEMON_NAME. This is done to separate configuration from logic and to keep a consistent style among daemon scripts.
• Use functions in /etc/rc.d/functions instead of duplicating their functionality.
• Include at least start, stop and restart as arguments to the script.

Available functions

• There are some functions provided by /etc/rc.d/functions:
  • stat_busy "message": set status busy for printed message (e.g. Starting daemon [BUSY])
  • stat_done: set status done (e.g. Starting daemon [DONE])
  • stat_fail: set status failed (e.g. Starting daemon [FAILED])
  • get_pid program: get PID of the program
  • ck_pidfile PID-file program: check whether PID-file is still valid for the program (e.g. ck_pidfile /var/run/daemon.pid daemon || rm -f /var/run/daemon.pid)
  • [add|rm]_daemon program: add/remove program to running daemons (stored in /run/daemons/)

Full list of functions is much longer and most possibilities (like way to control whether or not non-root users can launch daemon) are still undocumented and can be learned only from /etc/rc.d/functions source. See also man rc.d.

Example

The following is an example for crond. Look in /etc/rc.d for greater variety.

The configuration file:

/etc/conf.d/crond

ARGS="-S -l info"

The actual script:

/etc/rc.d/crond

#!/bin/bash

. /etc/rc.conf
. /etc/rc.d/functions

DAEMON=crond
ARGS=

[ -r /etc/conf.d/$DAEMON ] && . /etc/conf.d/$DAEMON

PID=$(get_pid $DAEMON)

case "$1" in
 start)
   stat_busy "Starting $DAEMON"
   [ -z "$PID" ] && $DAEMON $ARGS &>/dev/null
   if [ $? = 0 ]; then
     add_daemon $DAEMON
     stat_done
   else
     stat_fail
     exit 1
   fi
   ;;
 stop)
   stat_busy "Stopping $DAEMON"
   [ -n "$PID" ] && kill $PID &>/dev/null
   if [ $? = 0 ]; then
     rm_daemon $DAEMON
     stat_done
   else
     stat_fail
     exit 1
   fi
   ;;
 restart)
   $0 stop
   sleep 1
   $0 start
   ;;
 *)
   echo "usage: $0 {start|stop|restart}"  
esac