Re: "GIT_INDEX_FILE" environment variable

From: Linus Torvalds <torvalds@osdl.org>
Date: Apr 22, 2005, 19:24 UTC
Message-ID: <Pine.LNX.4.58.0504221147050.2344@ppc970.osdl.org>
In-Reply-To: <7vzmvr72j6.fsf@assigned-by-dhcp.cox.net>

On Thu, 21 Apr 2005, Junio C Hamano wrote:

Show 5 quoted lines

> 
> The commands I would want to take paths relative to the user cwd
> are quite limited; note that I just want these available to the
> user and I do not care which one, the core or Cogito, groks the
> cwd relative paths:

I've thought about this, and looked at the sources, and it wouldn't be horrible.

HOWEVER, the more I thought about it, the less sense it made. The fact is, you can do _exactly_ what you are talking about by just wrapping the calls in

	( cd $WORKING_DIR && git-cmd )

which simply doesn't have any downsides that I can see. It always does the right thing, and it means that the tools will never have to care about what the base is. Keeping the core tools is important, because if they mess up, you're in serious trouble. In contrast, if higher levels mess up, you're not likely to have caused anything irrevocable.

In fact, I probably shouldn't even have done the "--prefix=" stuff for check-out, since the common "check out in a new directory" case (not the "prefix file" case can be pretty easily emulated with a fairly trivial script, something like

	#!/bin/sh
	CURRENT_DIR=$(pwd)
	GIT_INDEX_FILE=${GIT_INDEX_FILE:-$CURRENT_DIR/.git/index}
	SHA1_FILE_DIRECTORY=${SHA1_FILE_DIRECTORY:-$CURRENT_DIR/.git/objects}
	TARGET=$1
	shift 1
	mkdir $TARGET && cd $TARGET && checkout-cache "$@"

but since it was (a) very easy to add to that particular program, and (b) exporting a while directory is pretty fundamental, I'll just leave that strange special case around.

So to the core tools, there really _are_ just two special things: the index file, and the place where to find the sha1 objects. The working directory is really nothing but "pwd", which can be trivially changed before invocation, ie the addition of a new environment variable really doesn't _buy_ anything except for complexity.

		Linus