etc.network.interfaces

auto eth0
iface eth0 inet static
    address 10.0.1.2
    netmask 255.255.255.0
    up /../ucarp_up_down.sh
    down /../ucarp_up_down.sh
    ucarp-vid-0 3
    ucarp-vip-0 10.0.1.3
    ucarp-password-0 badpasswd
    ucarp-vid-1 10
    ucarp-vip-1 10.0.1.10
    ucarp-password-1 badpasswd
iface eth0:ucarp:0 inet static
    address 10.0.1.3
    netmask 255.255.255.0
iface eth0:ucarp:1 inet static
    address 10.0.1.10
    netmask 255.255.255.0

ucarp-vip-down

#!/usr/bin/env bash

/sbin/ifdown $1:ucarp:$3

ucarp-vip-up

#!/usr/bin/env bash

/sbin/ifup $1:ucarp:$3

ucarp_start_stop.sh

#!/usr/bin/env bash

UCARP=/usr/sbin/ucarp
EXTRA_PARAMS="-x $IF_ALIAS"

if [ ! -x $UCARP ]; then
    exit 0
fi
if [ -z "$IF_UCARP_UPSCRIPT" ]; then
    IF_UCARP_UPSCRIPT=/../ucarp-vip-up
fi
if [ -z "$IF_UCARP_DOWNSCRIPT" ]; then
    IF_UCARP_DOWNSCRIPT=/../ucarp-vip-down
fi

if [ -n "$IF_UCARP_MASTER" ]; then
    if ! expr "$IF_UCARP_MASTER" : "no|off|false|0" > /dev/null; then
        EXTRA_PARAMS="$EXTRA_PARAMS -P"
    fi
fi

if [ -n "$IF_UCARP_ADVSKEW" ]; then
    EXTRA_PARAMS="$EXTRA_PARAMS -k $IF_UCARP_ADVSKEW"
fi

if [ -n "$IF_UCARP_ADVBASE" ]; then
    EXTRA_PARAMS="$EXTRA_PARAMS -b $IF_UCARP_ADVBASE"
fi

# Allow logging to custom facility
if [ -n "$IF_UCARP_FACILITY" ] ; then
    EXTRA_PARAMS="$EXTRA_PARAMS -f $IF_UCARP_FACILITY"
fi

if [ "$MODE" -eq "start" ] ; then
    START_STOP_ARGS="-b -m -S"
elif [ "$MODE" -eq "stop" ] ; then
    START_STOP_ARGS="-K"
fi

# Modified to use start / stop /daemon
if [ -n "$IF_UCARP_VID" -a -n "$IF_UCARP_VIP" -a
        -n "$IF_UCARP_PASSWORD" ]; then
    start-stop-daemon $START_STOP_ARGS -p "/var/run/ucarp.$IF_UCARP_VIP.pid" -x $UCARP -- -i $IFACE -s $IF_ADDRESS -z
        -v $IF_UCARP_VID -p $IF_UCARP_PASSWORD -a $IF_UCARP_VIP
        -u $IF_UCARP_UPSCRIPT -d $IF_UCARP_DOWNSCRIPT
        $EXTRA_PARAMS
fi

ucarp_up_down.sh

#!/usr/bin/env bash

UCARP_PARAMS=( IF_UCARP_UPSCRIPT IF_UCARP_DOWNSCRIPT IF_UCARP_MASTER IF_UCARP_ADVSKEW IF_UCARP_ADVBASE IF_UCARP_FACILITY IF_UCARP_VID IF_UCARP_VIP IF_UCARP_PASSWORD )

VIDS=( $( compgen -v IF_UCARP_VID ) )

for UCARP_VID in "${VIDS[@]}" ; do
    IFS="_" read -ra PARTS <<< "${UCARP_VID}"
    IF_ALIAS=${PARTS[3]}
    for PARAM in "${UCARP_PARAMS[@]}" ; do
        PARAM_ALIAS="${PARAM}_${IF_ALIAS}"
        eval ${PARAM}=\${${PARAM_ALIAS}-""}
    done
    source ucarp_start_stop.sh
done