+
−#!/bin/sh
+
−
+
−if [ x"$1" = x ]; then
+
− echo "Usage: $0 <cidr>" >&2; exit 255
+
−fi
+
−
+
−ip="$(echo "$1" | cut -d/ -f1)"
+
−len="$(echo "$1" | cut -d/ -f2)"
+
−if [ x"$((len%8))" != x0 ]; then
+
− echo "Prefix length must be a multiple of 8" >&2; exit 255
+
−fi
+
−octets="$((len/8))"
+
−for x in `seq 1 $octets` ; do
+
− echo $ip | cut -d. -f$x
+
−done | tr '\n' . | head -c -1 ; echo