shell 程序学习

cat   /etc/init.d/rc

#! /bin/bash
#
# rc            This file is responsible for starting/stopping
#               services when the runlevel changes.
#
# Original Author:      
#               Miquel van Smoorenburg,
#

# check a file to be a correct runlevel script
check_runlevel ()
{
    # Check if the file exists at all.
    [ -x "$1" ] || return 1

    # Reject backup files and files generated by rpm.
    case "$1" in
        *.rpmsave|*.rpmorig|*.rpmnew|*~|*.orig)
            return 1
            ;;
    esac
    return 0
}

# Now find out what the current and what the previous runlevel are.
argv1="$1"
set `/sbin/runlevel`
runlevel=$2
previous=$1
export runlevel previous

. /etc/init.d/functions

# See if we want to be in user confirmation mode
if [ "$previous" = "N" ]; then
    if [ -f /var/run/confirm ]; then
        echo $"Entering interactive startup"
    else
        echo $"Entering non-interactive startup"
    fi
fi

# Get first argument. Set new runlevel to this argument.
[ -n "$argv1" ] && runlevel="$argv1"

# Is there an rc directory for this new runlevel?
[ -d /etc/rc$runlevel.d ] || exit 0

# First, run the KILL scripts.
for i in /etc/rc$runlevel.d/K* ; do
    check_runlevel "$i" || continue

    # Check if the 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 the subsystem 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 if the 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 in confirmation mode, get user confirmation
    if [ -f /var/run/confirm ]; then
        confirm $subsys
        test $? = 1 && continue
    fi

    update_boot_stage "$subsys"
    # Bring the subsystem up.
    if [ "$subsys" = "halt" -o "$subsys" = "reboot" ]; then
        export LC_ALL=C
        exec $i start
    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
rm -f /var/run/confirm
if [ -x /usr/bin/rhgb-client ] && /usr/bin/rhgb-client --ping ; then
  /usr/bin/rhgb-client --quit
fi