RedHat9.0 /etc/rc.d/rc 程序注释

#! /bin/bash

#

# rc           This file is responsible for starting/stopping

#              services when the runlevel changes.

#

# Original Author:      

#              Miquel van Smoorenburg, <[email protected]>

#

 

# check a file to be a correct runlevel script

check_runlevel ()

{

    # Check ifthe file exists at all. -x:检测该文件名是否具有可执行属性

    [ -x"$1" ] || return 1

 

    # Rejectbackup files and files generated by rpm.

    case "$1"in

       *.rpmsave|*.rpmorig|*.rpmnew|*~|*.orig)

           return1

           ;;

    esac

    return 0

}

 

# Now find out what the current and what the previousrunlevel are.

argv1="$1"

set `/sbin/runlevel` #set a b : $1=a, $2=b,$#=2

#runlevel 结果:N 5,表示前一个运行级N(没有),当前运行级为5

#另外`/sbin/runlevel`可用$(/sbin/runlevel)替换

runlevel=$2

previous=$1

export runlevel previous

 

. /etc/init.d/functions

# functions文件中定义了一些函数如:checkpid(),daemon(),killproc(),

# pidfileofproc(),pidofproc(),status(),echo_success(),echo_failure()

# echo_passed(),echo_waring(),success(),failure(),passed(),warning()

# action(),strstr(),confirm(),

# . /etc/init.d/functions表示在当前shell中执行functions命令,此时会把functions

# 文件中函数的定义读到当前的shell中

 

# See if we want to be in user confirmation mode

# -f 该“文件名”是否为文件, || 如果前面的执行失败则继续执行后面的,否则不执行

# grep -i 表示忽略大小写的不同

if [ "$previous" ="N" ]; then

    if [ -f /var/run/confirm ] \

           || grep -i confirm /proc/cmdline>/dev/null ; then

       rm -f/var/run/confirm

       CONFIRM=yes

       exportCONFIRM

       echo$"Entering interactive startup"

    else

       echo$"Entering non-interactive startup"

    fi

fi

 

# Get first argument. Set new runlevel to thisargument.

# -n 判断字符串是否非为0,若为空则为false

[ -n "$argv1" ] &&runlevel="$argv1"

 

# Is there an rc directory for this new runlevel?

# -d 判断文件名是否为目录文件

[ -d /etc/rc$runlevel.d ] || exit 0

 

# First, run the KILL scripts.

# /var/lock 某些设备具有一次性写入特性,此时为了避免被其它人干扰正在运地的操作,因此,会将该设备lock(锁)起来,以确定该设备只能被单一程序所用

#${var#pattern}:表示从var的左边去掉最小匹配串

#${i#/etc/rc$runlevel.d/K??}:表示从i的最左边去掉“K??”三个字符,“?”表匹配任意一个字符

#-q 禁止所有的输出到标准输出,不管匹配行。如果选中输入行,以0 状态退出。

for i in /etc/rc$runlevel.d/K* ; do

    check_runlevel"$i" || continue

 

    # Check ifthe subsystem is already up.

    subsys=${i#/etc/rc$runlevel.d/K??}

    [ -f/var/lock/subsys/$subsys -o -f /var/lock/subsys/$subsys.init ] \

       ||continue

 

    # Bring thesubsystem down.

    if egrep -q"(killproc |action )" $i ; then

       $i stop

    else

       action$"Stopping $subsys: " $i stop

    fi

done

 

# Now run the START scripts.

for i in /etc/rc$runlevel.d/S* ; do

    check_runlevel"$i" || continue

 

    # Check ifthe subsystem is already up.

    subsys=${i#/etc/rc$runlevel.d/S??}

    [ -f/var/lock/subsys/$subsys -o -f /var/lock/subsys/$subsys.init ] \

       &&continue

          

    # If we're inconfirmation mode, get user confirmation

    # $? :表示上个命令的返回结果,如果执行成功,则返回0

    if [ -n "$CONFIRM" ]; then

       confirm $subsys

       case $? in

           0) :;;

           2)CONFIRM=;;

           *)continue;;

       esac

    fi

 

    # Bring thesubsystem up.

    if ["$subsys" = "halt" -o "$subsys" ="reboot" ]; then

       exportLC_ALL=C

       exec $istart

    fi

    if egrep -q"(daemon |action |success |failure )" $i 2>/dev/null \

           || ["$subsys" = "single" -o "$subsys" ="local" ]; then

       $i start

    else

       action$"Starting $subsys: " $i start

    fi

done

 

 

 

你可能感兴趣的:(shell,redhat,user,kill,File,action)