lfs-book-zh_CN/bootscripts/lfs/sysconfig/network-devices/ifup

#!/bin/sh
########################################################################
# Begin /sbin/ifup
#
# Description : Interface Up
#
# 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 SERVICE script
#               in the /lib/boot directory, to indicate what file the
#               service should source to get environmental variables.
#
########################################################################

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

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

. /lib/boot/functions

boot_mesg "Bringing up the ${1} interface..."
boot_mesg_flush

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

. $file

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

# Do not process this service if started by boot, and ONBOOT
# is not set to yes
if [ "${IN_BOOT}" = "1" -a "${ONBOOT}" != "yes" ]; then
   echo_skipped
   exit 0
fi

if [ -n "${SERVICE}" -a -x "/lib/boot/${SERVICE}" ]; then
   if [ -z "${CHECK_LINK}"         -o \
           "${CHECK_LINK}" = "y"   -o \
           "${CHECK_LINK}" = "yes" -o \
           "${CHECK_LINK}" = "1" ]; then

      #  Bring up the interface
      if ip link show ${IFACE} > /dev/null 2>&1; then
         link_status=`ip link show ${IFACE}`

         if [ -n "${link_status}" ]; then
            if ! echo "${link_status}" | grep -q UP; then
               ip link set ${IFACE} up
            fi
         fi

      else
         boot_mesg "Interface ${IFACE} doesn't exist." ${WARNING}
         echo_warning
      fi
   fi

   IFCONFIG=${file} /lib/boot/${SERVICE} ${IFACE} up

else
   boot_mesg "Unable to process ${file}.  Either" ${FAILURE}
   boot_mesg "the SERVICE variable was not set"
   boot_mesg "or the specified service cannot be executed."
   echo_failure
   exit 1
fi

# End /sbin/ifup