White Paper: Initscripts & logging

How to take advantage of it

One of the most asked questions about this new logging is:

How do I rewrite my init scripts to take advantage of this? The short answer is:

You don't. In general, most scripts written for earlier versions of Red Hat Linux should work transparently with the new scripts. For example, the following script should work fine:

Example 1. ypserv

#!/bin/sh
#
# ypserv:       Starts the yp-server
#
# Version:      @(#) /etc/rc.d/init.d/ypserv.init 1.0
#
# Author:       Joerg Mertin <smurphy@stargate.bln.sub.org>
#
# chkconfig: - 12 88
# description: ypserv is an implementation of the standard NIS/YP networking \
#              protocol.  It allows network-wide distribution of hostname, \
#              username, and other information databases. This is the NIS \
#              server, and is not needed on NIS clients.
# processname: ypserv
# config: /etc/ypserv.conf

# Source function library.
. /etc/rc.d/init.d/functions

# getting the YP-Domainname
. /etc/sysconfig/network

# See how we were called.
case "$1" in
  start)
        echo -n "Starting YP server services: "
        daemon ypserv
        echo
        touch /var/lock/subsys/ypserv
        ;;
  stop)
        echo -n "Stopping YP server services: "
        killproc ypserv
        rm -f /var/lock/subsys/ypserv
        echo
        ;;
  status)
        status ypserv
        ;;
  restart)
        $0 stop
        $0 start
        ;;
  *)
        echo "Usage: $0 {start|stop|status|restart}"
        exit 1
esac

exit 0

What we've done is modify the daemon and killproc functions (used by most scripts) to take advantage of the new logging and display functions, so that most script writers don't have to change their scripts.

daemon

The daemon function is used to start services. Its syntax is:

daemon [+/-nicelevel] [--check program] command

nicelevel is the nice level to run the command at - see man 1 nice for details.

program is the name of the service you are running if it's not the first argument of the command parameter. The canonical example is using su to run a service as a different user:

daemon --check xfs su xfs -c "xfs"

killproc

The killproc function is used to stop services. Its syntax is:

killproc program signal

where signal is the optional signal to send to the process.

If your init script uses these functions, it will automatically take advantage of the new logging and display functionality. If it doesn't, it will still be logged and displayed similarily at boot and shutdown, as scripts of this sort are run through initlog. However, this does mean that starting and stopping a service of this sort from the command line will not be logged.

We do not recommend init script authors writing scripts that specifically call logging and display functions, simply because it ties these scripts to specific versions of Red Hat Linux. However, if you feel that it is necessary to call some of these functions directly, the following are available:

success, failure

 

success/failure description

Logs that the action described by description succeeded/failed, and prints an appropriate marker.

action

 

action "some action" command

Runs command, logs whether the specified action succeeded or failed, and prints an appropriate display. For example:

action "Mounting NFS filesystems" mount -a -t nfs