lfs-book-zh_CN/bootscripts/lfs/sbin/ifdown

#!/bin/bash 
########################################################################
# Begin /sbin/ifdown
#
# Description : Interface Down
#
# Authors     : Nathan Coulson - nathan@linuxfromscratch.org
#               Kevin P. Fleming - kpfleming@linuxfromscratch.org
# Update      : Bruce Dubbs - bdubbs@linuxfromscratch.org
#
# Version     : LFS 7.0
#
# Notes       : the IFCONFIG variable is passed to the scripts found
#               in the /lib/services directory, to indicate what file the
#               service should source to get interface specifications.
#
########################################################################

RELEASE="7.0"

USAGE="Usage: $0 [ -hV ] [--help] [--version] interface"
VERSTR="LFS ifdown, version ${RELEASE}"

while [ $# -gt 0 ]; do
   case "$1" in
      --help | -h)     help="y"; break ;;

      --version | -V)  echo "${VERSTR}"; exit 0 ;;

      -*)              echo "ifup: ${1}: invalid option" >&2
                       echo "${USAGE}" >& 2
                       exit 2 ;;
                    
      *)               break ;;
   esac
done

if [ -n "$help" ]; then
   echo "${VERSTR}"
   echo "${USAGE}"
   echo
   cat << HERE_EOF
ifdown is used to bring down a network interface.  The interface
parameter, e.g. eth0 or eth0:2, must match the trailing part of the
interface specifications file, e.g. /etc/sysconfig/ifconfig.eth0:2.

HERE_EOF
   exit 0
fi

file=/etc/sysconfig/ifconfig.${1}

# Skip backup files
[ "${file}" = "${file%""~""}" ] || exit 0

. /lib/lsb/init-functions 

if [ ! -r "${file}" ]; then
   log_warning_msg "${file} is missing or cannot be accessed."
   exit 1
fi

. ${file}

if [ "$IFACE" = "" ]; then
   log_failure_msg "${file} does not define an interface [IFACE]."
   exit 1
fi

# We only need to first service to bring down the interface
S=`echo ${SERVICE} | cut -f1 -d" "`

if ip link show ${IFACE} > /dev/null 2>&1; then
   if [ -n "${S}" -a -x "/lib/services/${S}" ]; then
     IFCONFIG=${file} /lib/services/${S} ${IFACE} down
   else
     MSG="Unable to process ${file}.  Either "
     MSG="${MSG}the SERVICE variable was not set "
     MSG="${MSG}or the specified service cannot be executed."
     log_failure_msg "$MSG"
     exit 1
  fi
else
   log_warning_msg "Interface ${1} doesn't exist."
fi

# Leave the interface up if there are additional interfaces in the device
link_status=`ip link show ${IFACE} 2>/dev/null`

if [ -n "${link_status}" ]; then
   if [ "$(echo "${link_status}" | grep UP)" != "" ]; then
      if [ "$(ip addr show ${IFACE} | grep 'inet ')" == ""  ]; then
         log_info_msg "Bringing down the ${IFACE} interface..."
         ip link set ${IFACE} down
         evaluate_retval
      fi
   fi
fi

# End /sbin/ifdown