Since mac osx does not have the sha1sum tool installed (why, Apple, why?) this script gets openssl to produce the same output.

sha1sum.sh

#!/bin/sh

# since mac osx does not have the sha1sum tool installed
# this script gets openssl to produce the same output
 
if [ $# -ne 1 ] 
then
 	echo "Usage:\n\n$0 [file to check]"
else
	openssl sha1 $1 | sed 's/.*(\(.*\))= \(.*\)$/\2 \1/'
fi