lfs-book-zh_CN/bootscripts/lfs/sbin/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 7.2
#
# Notes       : The IFCONFIG variable is passed to the SERVICE script
#               in the /lib/services directory, to indicate what file the
#               service should source to get interface specifications.
#
########################################################################

up()
{
  if ip link show $1 > /dev/null 2>&1; then
     link_status=`ip link show $1`

     if [ -n "${link_status}" ]; then
        if ! echo "${link_status}" | grep -q UP; then
           ip link set $1 up
        fi
     fi

  else
     log_failure_msg "\nInterface ${IFACE} doesn't exist."
     exit 1
  fi
}

RELEASE="7.2"

USAGE="Usage: $0 [ -hV ] [--help] [--version] interface"
VERSTR="LFS ifup, 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
ifup is used to bring up 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

log_info_msg "Bringing up the ${1} interface... "

if [ ! -r "${file}" ]; then
   log_failure_msg2 "${file} is missing or cannot be accessed." 
   exit 1
fi

. $file

if [ "$IFACE" = "" ]; then
   log_failure_msg2 "${file} does not define an interface [IFACE]."
   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
   log_info_msg2 "skipped"
   exit 0
fi

for S in ${SERVICE}; do
  if [ ! -x "/lib/services/${S}" ]; then
    MSG="\nUnable to process ${file}.  Either " 
    MSG="${MSG}the SERVICE '${S} was not present "
    MSG="${MSG}or cannot be executed."
    log_failure_msg "$MSG"
    exit 1
  fi
done

# Create/configure the interface
for S in ${SERVICE}; do 
  IFCONFIG=${file} /lib/services/${S} ${IFACE} up
done

# Bring up the interface and any components
for I in $IFACE $INTERFACE_COMPONENTS; do up $I; done

# Set MTU if requested. Check if MTU has a "good" value.
if test -n "${MTU}"; then
   if [[ ${MTU} =~ ^[0-9]+$ ]] && [[ $MTU -ge 68 ]] ; then
      for I in $IFACE $INTERFACE_COMPONENTS; do 
         ip link set dev $I mtu $MTU; 
      done
   else
      log_info_msg2 "Invalid MTU $MTU"
   fi
fi 

# Set the route default gateway if requested
if [ -n "${GATEWAY}" ]; then
   if ip route | grep -q default; then
      log_warning_msg "\nGateway already setup; skipping."
   else
      log_info_msg "Setting up default gateway..."
      ip route add default via ${GATEWAY} dev ${IFACE}
      evaluate_retval
   fi
fi

# End /sbin/ifup