D.25. /sbin/ifdown

#### Linux From Scratch - Version 10.0-rc1

### Appendix D. Boot and sysconfig scripts version-20200802

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# D.25. /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

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