gz99

#!/bin/bash
set -e

command -v advdef > /dev/null || echo advdef is not installed. Install for a better compression ratio
command -v 7z > /dev/null || echo 7z is not installed. Install for a better compression ratio

if [ -z "$1" ]
then
	echo "USAGE: $0 OUTPUT.gz"
	echo "Compresses stdin to OUTPUT.gz"
	exit 1
fi


OUT=$1


time gzip -9 > $OUT.new
mv $OUT.new $OUT
ORIG_HASH=`gunzip < $OUT`

accept_new(){
if [ ".`gunzip < $OUT.new`" = ".$ORIG_HASH" ]
then
	oldsize=$(stat -f%z "$OUT")
	newsize=$(stat -f%z "$OUT.new")
	if [ $oldsize -gt $newsize ]
	then
		echo "$oldsize->$newsize: Saved $((oldsize-newsize)) bytes."
		mv -f $OUT.new $OUT
	else
		echo "$oldsize->$newsize: No savings, new file discarded."
	fi
else
	echo $OUT.new corrupt. Deleting.
	rm $OUT.new
fi
}
echo Finished GZIP compression, you now have a complete gz file
#echo You can stop here, but we will try to make the file smaller for you.
#rm $OUT.new || true
#time 7z a $OUT.new -mx=9 -tgzip $OUT
#gunzip < $OUT | time 7z a $OUT.new -mx=9 -tgzip -si
#time 7z a dummy -mx=9 -tgzip -so -si $OUT.new $OUT

#accept_new
#cp $OUT $OUT.new
#echo Trying advdef compression
#time advdef -4 -z $OUT.new # instead link?
#accept_new