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When the "git" wrapper is invoked, we prepend the baked-in
exec-path to our PATH, so that any sub-processes we exec
will all find the git-foo commands that match the wrapper
version.
If you invoke git with an absolute path, like:
/usr/bin/git foo
we also prepend "/usr/bin" to the PATH. This was added long
ago by by 231af83 (Teach the "git" command to handle some
commands internally, 2006-02-26), with the intent that
things would just work if you did something like:
cd /opt
tar xzf premade-git-package.tar.gz
alias git=/opt/git/bin/git
as we would then find all of the related external commands
in /opt/git/bin. I.e., it made git runtime-relocatable,
since at the time of 231af83, we installed all of the git
commands into $(bindir). But these days, that is not enough.
Since f28ac70 (Move all dashed-form commands to libexecdir,
2007-11-28), we do not put commands into $(bindir), and you
actually need to convert "/usr/bin" into "/usr/libexec". And
not just for finding binaries; we want to find $(sharedir),
etc, the same way. The RUNTIME_PREFIX build knob does this
the right way, by assuming a sane hierarchy rooted at
"$prefix" when we run "$prefix/bin/git", and inferring
"$prefix/libexec/git-core", etc.
So this feature (prepending the argv[0] dirname to the PATH)
is broken for providing a runtime prefix, and has been for
many years. Does it do anything for other cases?
For the "git" wrapper itself, as well as any commands
shipped by "git", the answer is no. Those are already in
git's exec-path, which is consulted first. For third-party
commands which you've dropped into the same directory, it
does include them. So if you do
cd /opt
tar xzf git-built-specifically-for-opt-git.tar.gz
cp third-party/git-foo /opt/git/bin/git-foo
alias git=/opt/git/bin/git
it does mean that we will find the third-party "git-foo",
even if you do not put /opt/git/bin into your $PATH. But
the flipside of this is that we will bump the precedence of
_other_ third-party tools that happen to be in the same
directory as git. For example, consider this setup:
1. Git is installed by the system in /usr/bin. There are
other system utilities in /usr/bin. E.g., a system
"vi".
2. The user installs tools they prefer in /usr/local/bin.
E.g., vim with a "vi" symlink. They set their PATH to
/usr/local/bin:/usr/bin to prefer their custom tools.
3. Running /usr/bin/git puts "/usr/bin" at the front of
their PATH. When git invokes the editor on behalf of
the user, they get the system vi, not their normal vim.
There are other variants of this, including overriding
system ruby and python (which is quite common using tools
like "rvm" and "virtualenv", which use relocatable
hierarchies and $PATH settings to get a consistent
environment).
Given that the main motivation for git placing the argv[0]
dirname into the PATH has been broken for years, that the
remaining cases are obscure and unlikely (and easily fixed
by the user just setting up their $PATH sanely), and that
the behavior is hurting real, reasonably common use cases,
it's not worth continuing to do so.
Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
////////////////////////////////////////////////////////////////
Git - the stupid content tracker
////////////////////////////////////////////////////////////////
"git" can mean anything, depending on your mood.
- random three-letter combination that is pronounceable, and not
actually used by any common UNIX command. The fact that it is a
mispronunciation of "get" may or may not be relevant.
- stupid. contemptible and despicable. simple. Take your pick from the
dictionary of slang.
- "global information tracker": you're in a good mood, and it actually
works for you. Angels sing, and a light suddenly fills the room.
- "goddamn idiotic truckload of sh*t": when it breaks
Git is a fast, scalable, distributed revision control system with an
unusually rich command set that provides both high-level operations
and full access to internals.
Git is an Open Source project covered by the GNU General Public
License version 2 (some parts of it are under different licenses,
compatible with the GPLv2). It was originally written by Linus
Torvalds with help of a group of hackers around the net.
Please read the file INSTALL for installation instructions.
See Documentation/gittutorial.txt to get started, then see
Documentation/giteveryday.txt for a useful minimum set of commands, and
Documentation/git-commandname.txt for documentation of each command.
If git has been correctly installed, then the tutorial can also be
read with "man gittutorial" or "git help tutorial", and the
documentation of each command with "man git-commandname" or "git help
commandname".
CVS users may also want to read Documentation/gitcvs-migration.txt
("man gitcvs-migration" or "git help cvs-migration" if git is
installed).
Many Git online resources are accessible from http://git-scm.com/
including full documentation and Git related tools.
The user discussion and development of Git take place on the Git
mailing list -- everyone is welcome to post bug reports, feature
requests, comments and patches to git@vger.kernel.org (read
Documentation/SubmittingPatches for instructions on patch submission).
To subscribe to the list, send an email with just "subscribe git" in
the body to majordomo@vger.kernel.org. The mailing list archives are
available at http://news.gmane.org/gmane.comp.version-control.git/,
http://marc.info/?l=git and other archival sites.
The maintainer frequently sends the "What's cooking" reports that
list the current status of various development topics to the mailing
list. The discussion following them give a good reference for
project status, development direction and remaining tasks.