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From: Jeff King <peff@peff.net>
To: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Cc: mhagger@alum.mit.edu, Git Mailing List <git@vger.kernel.org>,
	Junio C Hamano <gitster@pobox.com>,
	dnj@google.com, Johannes Schindelin <Johannes.Schindelin@gmx.de>,
	prohaska@zib.de, john@keeping.me.uk, stanhu@gmail.com,
	richardc@unixbeard.net, Joey Hess <id@joeyh.name>
Subject: Re: [RFC/PATCH 0/5] stop installing old libexec aliases like "git-init"
Date: Sat, 17 Nov 2018 01:39:41 -0500
Message-ID: <20181117063940.GA31057@sigill.intra.peff.net> (raw)
In-Reply-To: <87in0w25gc.fsf@evledraar.gmail.com>

On Fri, Nov 16, 2018 at 08:22:11PM +0100, Ævar Arnfjörð Bjarmason wrote:

> So maybe we should just document this interface better. It seems one
> implicit dependency is that we expect a manpage for the tool to exist
> for --help.

Yeah, I think this really the only problematic assumption. The rest of
"-c", "--git-dir", etc, are just manipulating the environment, and that
gets passed through to sub-invocations of Git (so if I have a script
which calls git-config, it will pick up the "-c" config).

It would be nice if there was a way to ask "is there a manpage?", and
fallback to running "git-cmd --help". But:

  1. I don't think there is a portable way to query that via man. And
     anyway, depending platform and config, it may be opening a browser
     to show HTML documentation (or I think even texinfo?).

  2. We can just ask whether "man git-sizer" (or whatever help display
     command) returned a non-zero exit code, and fall back to "git-sizer
     --help". But there's an infinite-loop possibility here: running
     "git-sizer --help" does what we want. But if "man git-log" failed,
     we'd run "git-log --help", which in turn runs "git help log", which
     runs "man git-log", and so on.

     You can break that loop with an environment variable for "I already
     tried to show the manpage", which would I guess convert "--help" to
     "-h".

So it's maybe do-able, but not quite as trivial as one might hope.

> But I don't remember the details, and can't reproduce it now with:
> 
>     $ cat ~/bin/git-sigint 
>     #!/usr/bin/env perl
>     $SIG{INT} = sub { warn localtime . " " . $$ };
>     sleep 1 while 1;
>     $ git sigint # or git-sigint
>     [... behaves the same either way ...]
> 
> So maybe it was something else, or I'm misremembering...

I think that generally works because hitting ^C is going to send SIGINT
to the whole process group. A more interesting case is:

  git sigint &
  kill -INT $!

There $! is a parent "git" process that is just waiting on git-sigint to
die. But that works, too, because the parent relays common signals due
to 10c6cddd92 (dashed externals: kill children on exit, 2012-01-08). So
you might have been remembering issues prior to that commit (or uncommon
signals; these come from sigchain_push_common).

-Peff

  reply index

Thread overview: 53+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-06 23:34 What's cooking in git.git (Mar 2018, #02; Tue, 6) Junio C Hamano
2018-03-07 12:34 ` Johannes Schindelin
2018-03-08  9:22   ` Ævar Arnfjörð Bjarmason
2018-03-08 13:12     ` Daniel Jacques
2018-03-13 12:36       ` Why don't we symlink libexec/git-core/* to bin/git? Ævar Arnfjörð Bjarmason
2018-03-13 18:36         ` Junio C Hamano
2018-03-13 19:32           ` Randall S. Becker
2018-03-13 20:39           ` [PATCH 0/3] Makefile: add a INSTALL_SYMLINKS option Ævar Arnfjörð Bjarmason
2018-03-13 20:39           ` [PATCH 1/3] Makefile: fix broken bindir_relative variable Ævar Arnfjörð Bjarmason
2018-03-13 20:39           ` [PATCH 2/3] Makefile: add a gitexecdir_relative variable Ævar Arnfjörð Bjarmason
2018-03-13 20:39           ` [PATCH 3/3] Makefile: optionally symlink libexec/git-core binaries to bin/git Ævar Arnfjörð Bjarmason
2018-03-14  7:20             ` Johannes Sixt
2018-03-14 10:14               ` Ævar Arnfjörð Bjarmason
2018-03-14 17:21                 ` Linus Torvalds
2018-03-15 17:05                   ` Johannes Schindelin
2018-03-15 17:42                     ` Linus Torvalds
2018-03-16 11:48                       ` Johannes Schindelin
2018-03-16 12:43                         ` Ævar Arnfjörð Bjarmason
2018-03-19 11:34                           ` Johannes Schindelin
2018-03-19 21:21                             ` Linus Torvalds
2018-11-02 22:37                           ` [RFC/PATCH 0/5] stop installing old libexec aliases like "git-init" Ævar Arnfjörð Bjarmason
2018-11-03  1:17                             ` Junio C Hamano
2018-11-05 11:36                               ` Ævar Arnfjörð Bjarmason
2018-11-12 13:33                             ` Johannes Schindelin
2018-11-16 10:38                             ` Ævar Arnfjörð Bjarmason
2018-11-16 16:00                               ` Michael Haggerty
2018-11-16 19:22                                 ` Ævar Arnfjörð Bjarmason
2018-11-17  6:39                                   ` Jeff King [this message]
2018-11-22 12:48                                     ` Johannes Schindelin
2018-11-22 16:06                                       ` Jeff King
2018-11-23 11:19                                         ` Johannes Schindelin
2018-11-02 22:37                           ` [RFC/PATCH 1/5] Makefile: move long inline shell loops in "install" into helper Ævar Arnfjörð Bjarmason
2018-11-04  1:09                             ` Eric Sunshine
2018-11-12 14:03                             ` Johannes Schindelin
2018-11-12 14:42                               ` Ævar Arnfjörð Bjarmason
2018-11-12 16:32                                 ` Johannes Schindelin
2018-11-16 10:32                                   ` Ævar Arnfjörð Bjarmason
2018-11-02 22:37                           ` [RFC/PATCH 2/5] Makefile: conform some of the code to our coding standards Ævar Arnfjörð Bjarmason
2018-11-02 22:37                           ` [RFC/PATCH 3/5] Makefile: stop hiding failures during "install" Ævar Arnfjörð Bjarmason
2018-11-02 22:37                           ` [RFC/PATCH 4/5] Makefile: add NO_INSTALL_SYMLINKS_FALLBACK switch Ævar Arnfjörð Bjarmason
2018-11-04  1:01                             ` Eric Sunshine
2018-11-02 22:37                           ` [RFC/PATCH 5/5] Makefile: Add a NO_INSTALL_BUILTIN_EXECDIR_ALIASES flag Ævar Arnfjörð Bjarmason
2018-11-04  1:04                             ` Eric Sunshine
2018-11-12 14:14                             ` Johannes Schindelin
2018-03-15 17:03               ` [PATCH 3/3] Makefile: optionally symlink libexec/git-core binaries to bin/git Johannes Schindelin
2018-03-14 10:18         ` Why don't we symlink libexec/git-core/* to bin/git? Ævar Arnfjörð Bjarmason
2018-03-14 16:07           ` Junio C Hamano
2018-03-15 17:16             ` Johannes Schindelin
2018-03-16 17:29               ` Duy Nguyen
2018-03-30  8:59                 ` Johannes Schindelin
2018-03-09  6:15 ` What's cooking in git.git (Mar 2018, #02; Tue, 6) Martin Ågren
2018-03-09  9:54   ` Duy Nguyen
2018-03-09 17:19   ` Junio C Hamano

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