Git server-side 'update' hook to reject changes to 'release' branches if the changes contain one or more commits present on the 'develop' branch

update

#!/bin/bash

# --- Command line
refname="$1"
oldrev="$2"
newrev="$3"

$(echo $refname | grep -q /release/)
on_release_branch=$?
if [ $on_release_branch -eq 0 ] && [ "$oldrev" != "0000000000000000000000000000000000000000" ]; then
	echo "refname is: $refname"
	echo "oldrev is: $oldrev"
	echo "newrev is: $newrev"
	if [ "$(git log --oneline $oldrev..$newrev | wc -l)" -ne "$(git log --oneline $oldrev..$newrev --not develop | wc -l)" ]; then
    		echo "Rejected: the following commits from develop are present"
		comm -23 <(echo | git log --oneline $oldrev..$newrev | grep -o "^[a-z0-9]\+") <(echo | git log --oneline $oldrev..$newrev --not develop | grep -o "^[a-z0-9]\+")
       	exit 1
    fi
else 
    exit 0
fi