From: Jeff King <peff@peff.net>
Date: Tue, 14 Feb 2012 19:05:15 GMT
Subject: Re: [RFC PATCH 0/3] git-p4: move to toplevel
Message-ID: <20120214190515.GB12072@sigill.intra.peff.net>
In-Reply-To: <7vaa4l8diz.fsf@alter.siamese.dyndns.org>

On Tue, Feb 14, 2012 at 10:40:04AM -0800, Junio C Hamano wrote:

> I do not think tilde in $PATH is expanded by exec*p family to begin with,
> so it is not "dash" but POSIX, I would think.  It is bash that is harming
> other programs, by trying to be more helpful, encouraging this user
> mistake to add ~ literally on the PATH.

Hmm. There is an interesting ramification for run-command's "use_shell"
optimization. Typically, git runs all of the user-provided commands
given to it via the shell. But if the command contains no
meta-characters, we skip the shell invocation as an optimization, since
the shell should simply be word-splitting and calling exec, and the
behavior will be identical.

But if your shell handles PATH entries differently, then there is a
difference. I.e., doing this:

  mkdir junk
  ln -s /usr/bin/vi junk/my-editor
  export PATH=~/junk:$PATH
  export GIT_EDITOR=my-editor
  git commit

might work without the optimization, but not with.

We could check PATH and disable the optimization in that case, but I
suspect it is not worth it, as:

  1. People who put a literal "~" in their PATH get what they deserve
     anyway. :)

  2. We explicitly run "sh" in such situations, not SHELL_PATH. Even if
     "sh" is bash, I believe it should look at its own argv[0] and put
     itself into a more POSIX-y mode (but I didn't test).

-Peff