Re: Portability of git shell scripts?

On Wed, May 4, 2016 at 11:20 PM, Jeff King [off-list ref] wrote:

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

quoted

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.

In general ksh (88 or 93) is posix compliant... and bash is moving away
from posix. :-) But I know what you mean.

quoted

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.

My last compile of git 2.2.2 did far better than the current 2.8.2. So
it looks like
there were more recent changes that broke portability.

quoted

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.

Regarding [2] this was a bug which was fixed quite fast. To me this is no
real showstopper. Modernity of ksh93 depends on the letter after the 93 :-)

quoted

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.

I tried a build with SHELL_PATH=/bin/bash. Many problems "went away".
Others appeared. I'll give it a few more days to look into it.

First finding:
make test does not make it through t3513-revert-submodule.sh anymore.
The test is not portable since it uses the z-flags of GNU-tar. When -z
is removed,
(and extension is changed back to tar) everything runs and tests smoothly.

Is this report enough to start the magic to change things?

Regards,
Armin