A pre-receive hook for rejecting things not tagged

pre-receive

#!/bin/sh

validate_ref()
{
	# --- Arguments
	oldrev=$(git rev-parse $1)
	newrev=$(git rev-parse $2)
	refname="$3"

	# oldrev could be 0s which means creating refname
	# newrev could be 0s which means deleting refname

	case "$refname" in
		refs/tags/*)
		    tag=$(expr "$refname" : "refs/tags/\(.*\)")
			topictag=$(expr "$tag" : "\(.*/.*\)")
			if [ 0 -ne $(expr "$newrev" : "0*$") ]; then # deleting
				# only topic tags can be deleted
				if [ -z $topictag ]; then
					fail=1
					echo >&2 "*** Deleting the tag $tag is not permitted. ***"
					return
				fi
				return
			fi
			if [ "tag" != $(git cat-file -t $newrev) ]; then # unannotated tag
				fail=1
				echo >&2 "*** The un-annotated tag, $tag, is not allowed in this repository."
				echo >&2 "*** Use 'git tag [ -a | -s ]' for tags you want to propagate."
				return
			fi
			;;
		*)
			fail=1
			echo >&2 "*** pre-receive hook does not understand ref $refname in this repository. ***"
			echo >&2 "*** Contact the repository administrator. ***"
			;;
	esac
}

fail=""

# Allow dual mode: run from the command line just like the update hook, or
# if no arguments are given then run as a hook script
if [ -n "$1" -a -n "$2" -a -n "$3" ]; then
	# Output to the terminal in command line mode - if someone wanted to
	# resend an email; they could redirect the output to sendmail
	# themselves
	PAGER= validate_ref $2 $3 $1
else
	while read oldrev newrev refname
	do
		validate_ref $oldrev $newrev $refname
	done
fi

if [ -n "$fail" ]; then
	exit $fail
fi

Is this for github or git? github doesn't support pre-receive, does it? so I assume this is for git only?