Re: Portability of git shell scripts?

From: Jeff King <peff@peff.net>
Date: May 4, 2016, 21:20 UTC
Message-ID: <20160504212028.GG21259@sigill.intra.peff.net>
In-Reply-To: <CALR6jEh5dAcnqiyo4kXkj+8imfQQd0nT=baPOW_qbJpJwmFsyw@mail.gmail.com>

On Wed, May 04, 2016 at 08:17:38PM +0200, Armin Kunaschik wrote:

> I'm trying to compile/test/use git 2.8.2 on AIX 6.1 with no bash available.
> /bin/sh is a hard link to /bin/ksh which is a ksh88, a posix shell.
> Is this supposed to work?

We aim for a practical subset of Bourne shells, including bash, dash, ash, ksh, etc. There's at least one Bourne-ish shell known not to work, which is Solaris /bin/sh[1]. POSIX is usually a good guide, but we aim for practical portability more than adhering strictly to the standards document.

I've tested with mksh in the past (though it's possible that we've introduced a regression since then). But I think we've run into problems with ksh93[2]. I don't know about ksh88, or what construct it doesn't like. It may or may not be easy to work around.

Show 5 quoted lines

> As an example: make test fails on nearly every t34* test and on tests
> which contain rebase.
> The installation of bash (and manually changing the shebang to
> /bin/bash) "fixes" all rebase test failures. So obviously git-rebase
> is not portable at some point.

Right. Any modern-ish Bourne shell will do, so moving to bash is one way to fix it.

> Does it make any sense to put work into making these scripts portable,
> that is, work with posix shells?

Maybe. :) If you can find what it is that ksh88 is unhappy with, we can see how painful it is to adapt to. But given my looking into ksh93 in [2], I suspect it will be easier to just use a more modern shell.

> And, as last resort, is it possible to configure git use bash in some
> or all shell scripts?

You can set SHELL_PATH in your config.mak file.

-Peff

[1] Solaris /bin/sh doesn't even understand $(), so we declared it as
    hopeless long ago. I think most people just replace it with bash,
    but I suspect /usr/xpg6/bin/sh probably works, too.

[2] http://thread.gmane.org/gmane.comp.version-control.git/268657/focus=268666