git-test-commit

#!/bin/sh
if [ $# -lt 1 -o $# -gt 3 ]; then
	echo 'Usage: git test-commit <filename> [<content> [<message>]]' >&2
	exit 1
fi

if git rev-parse --is-inside-work-tree >/dev/null >&1; then
	if [ `git rev-parse --is-inside-work-tree` = false ]; then
		echo "Must be run from within a git work-tree" >&2
		exit 1
	fi
else
	exit 1
fi

file="$1"
if [ $# -gt 1 ]; then
	content="$2"
else
	content="$file"
fi

GIT_INDEX=`mktemp -t git-test-commit.XXXXXXXXXX`
GIT_AUTHOR_NAME='test'
GIT_AUTHOR_EMAIL='nobody@localhost'
[ -n "$GIT_INDEX" -a -w "$GIT_INDEX" ] || exit 1
_cleanup(){ rm -f "$GIT_INDEX"; }
trap _cleanup INT HUP TERM EXIT

export GIT_INDEX GIT_AUTHOR_NAME GIT_AUTHOR_EMAIL

if git show-ref --quiet --head; then
	git read-tree HEAD: || exit 1	
else
	git read-tree --empty || exit 1
fi
git update-index --add --cacheinfo 100644 `(
	if git cat-file -t "HEAD:$file" >/dev/null 2>&1; then
		git cat-file blob "HEAD:$file" 2>/dev/null
	fi
	printf '%s\n' "$content"
) | git hash-object -t blob -w --stdin` "$file"

if [ $# -gt 2 ]; then
	message="$3"
elif git cat-file -t "HEAD:$file" >/dev/null 2>&1; then
	message="appended to $file"
else
	message="added $file"
fi

git commit --quiet -m "$message"