| 1234567891011121314151617181920212223242526272829 | #!/bin/sh[ -x /usr/sbin/brctl ] || exit 0case "$IF_BRIDGE_PORTS" in    "")        exit 0        ;;    none)        INTERFACES=""        ;;    *)        INTERFACES="$IF_BRIDGE_PORTS"        ;;esacbrctl addbr $IFACE || exit 1for IF in $INTERFACES; do  if ! grep -q $IF /proc/net/dev; then    echo "Error: interface '$IF' does not exist!"    brctl delbr $IFACE    exit 1  fi  brctl addif $IFACE $IF  ip link set up dev $IFdoneexit 0
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