stockholm/bin/netmask-to-prefix

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2015-05-20 23:56:08 +00:00
#! /bin/sh
set -euf
netmask=$1
binaryNetmask=$(echo $1 | sed 's/^/obase=2;/;s/\./;/g' | bc | tr -d \\n)
binaryPrefix=$(echo $binaryNetmask | sed -n 's/^\(1*\)0*$/\1/p')
if ! echo $binaryPrefix | grep -q .; then
echo $0: bad netmask: $netmask >&2
exit 4
fi
printf %s $binaryPrefix | tr -d 0 | wc -c