系统启动脚本分析(5)--syslog脚本

#!/bin/bash
#
# syslog        Starts syslogd/klogd.
#
#
# chkconfig: 2345 12 88
# description: Syslog is the facility by which many daemons use to log 
# messages to various system log files.  It is a good idea to always 
# run syslog.
### BEGIN INIT INFO
# Provides: $syslog
### END INIT INFO

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

[ -f /sbin/syslogd ]'  'exit 0
[ -f /sbin/klogd ]'  'exit 0
##首先判断syslogd和klogd这两个文件是否存在,如果存在才能执行下面的脚本

# Source config
if [ -f /etc/sysconfig/syslog ] ; then
	. /etc/sysconfig/syslog
##导入syslog这个配置文件
else
	SYSLOGD_OPTIONS="-m 0"
	KLOGD_OPTIONS="-2"
fi

RETVAL=0

umask 077

start() {
 	echo -n $"Starting system logger: "
	daemon syslogd $SYSLOGD_OPTIONS
##syslogd是系统运行监测程序,在系统产生错误时,这个daemon负责把错误信息写到固定的地方
##daemon这个函数在functions这个文件中定义
	RETVAL=$?
##RETVAL设置为启动syslogd这个daemon是否成功的返回值
	echo
	echo -n $"Starting kernel logger: "
	daemon klogd $KLOGD_OPTIONS
##klogd是内核运行监测程序,当内核出错时,这个daemon负责把错误信息通知用户
	echo
	[ $RETVAL -eq 0 ] && touch /var/lock/subsys/syslog
##如果syslogd启动成功,则在/var/lock/subsys/下面建立一个空文件syslog
	return $RETVAL
}	
stop() {
	echo -n $"Shutting down kernel logger: "
	killproc klogd
##killproc是在functions这个文件中定义的函数
	echo
	echo -n $"Shutting down system logger: "
	killproc syslogd
	RETVAL=$?
	echo
	[ $RETVAL -eq 0 ] && rm -f /var/lock/subsys/syslog
	return $RETVAL
}
rhstatus() {
	status syslogd
	status klogd
}
restart() {
	stop
	start
}	

case "$1" in
  start)
  	start
	;;
  stop)
  	stop
	;;
  status)
  	rhstatus
	;;
  restart|reload)
  	restart
	;;
  condrestart)
  	[ -f /var/lock/subsys/syslog ] && restart'  ':
	;;
  *)
	echo $"Usage: $0 {start|stop|status|restart|condrestart}"
	exit 1
esac

exit $?