Re: [PATCH] run-command.c: print env vars when GIT_TRACE is set
- Date: Thu, 11 Jan 2018 05:07:35 -0500
- From: Jeff King <peff@xxxxxxxx>
- Subject: Re: [PATCH] run-command.c: print env vars when GIT_TRACE is set
On Wed, Jan 10, 2018 at 05:48:35PM +0700, Nguyễn Thái Ngọc Duy wrote:
> Occasionally submodule code could execute new commands with GIT_DIR set
> to some submodule. GIT_TRACE prints just the command line which makes it
> hard to tell that it's not really executed on this repository.
> Print env variables in this case. Note that the code deliberately ignore
> variables unsetting because there are so many of them (to keep git
> environment clean for the next process) and really hard to read.
I like this, and I'm pretty sure it would have helped me debug at least
once in the past. I did notice one funny thing, though I think it was
largely there before.
The output for a single command is pretty shell-like due to the quoting:
$ GIT_TRACE=1 ./git upload-pack . >/dev/null
[...]run_command: 'git-upload-pack' '.'
You could copy and paste that to a shell if you wanted. And with
environment variables, that remains so:
$ GIT_TRACE=1 ./git ls-remote https://github.com/git/git >/dev/null
[...]run_command: 'GIT_DIR=.git' 'git-remote-https' 'https://[...]'
But if we're actually running a command via the shell, it all gets
quoted as one argument:
$ GIT_TRACE=1 GIT_PAGER='foo | bar' ./git log
[...]run_command: 'LV=-c' 'foo | bar'
which is kind of weird, as that's not something that can be run in a
shell. This isn't introduced by your patch at all, but I noticed it more
because of the shell-like environment variable output.
We actually used to print a separate:
exec: /bin/sh -c 'foo | bar'
line when we invoked a shell, which would arguably be the right place to
show the env variables for such a case. But that went away with
3967e25be1 (run-command: prepare command before forking, 2017-04-19).
I think it might be helpful if we added back in "/bin/sh -c" to the
run_command line when "use_shell" is in effect (and when we're not doing
our "skip the shell" trickery). But that's totally orthogonal to your
And anyway, it's just tracing output, so I don't think it's incredibly
important either way. It was just something I noticed while looking at
your patch's output.