git_hooks/pre-commit for checking gofmt (portable Posix shell version)

pre-commit.sh

#! /bin/sh

if command -v gofmt > /dev/null 2>&1; then
	BAD=''
	while IFS= read -r f; do
		if echo "$f" | grep -q '\.go$'; then
			HASH="$(git ls-files --stage -- "$f" | awk '{print $2}')"
			if [ "$(git show "$HASH" | gofmt -l 2>&1)" ]; then
				if [ -z "$BAD" ]; then
					BAD='Y'
					echo The following files have gofmt errors: >&2
				fi
				printf '	%s\n' "$f" >&2
			fi
		fi
	done <<- EOT
	$( git diff --cached --name-only --diff-filter=AM )
	EOT
	if [ -n "$BAD" ]; then
		exit 1
	fi
fi