Bash script to add a delay to the localhost interface on Linux machines

gistfile1.sh

#!/bin/bash
# Copyright 2010 Eric Ryan Harrison <me@ericharrison.info>
# Inspired by:
#       http://daniel.haxx.se/blog/2010/12/14/add-latency-to-localhost/

if [ -n "$1" ]
then
        if [ "$1" = "off" ]
        then
                tc qdisc del dev lo root
        else
                tc qdisc add dev lo root handle 1:0 netem delay $1msec
        fi
else
        echo 'Usage: localdelay [TIME_IN_MILLISECONDS|off]'
        echo 'Example:'
        echo '  localdelay 20'
        echo '          This will add a 20 millisecond delay to localhost'
        echo '          and pings will take 40+ms to respond.'
        echo '  localdelay off'
        echo '          Turns off delay.'
fi