git's directory is _prepended_ to PATH when called with an absolute path

For example, if I run git using:

$ /usr/bin/git

then /usr/bin is prepended to the path. Is this intentional? If it is, why?

This causes issues with Ruby git hooks, because Ruby version managers 
rely on custom settings in PATH to select the Ruby executable, and 
there's usually a system Ruby living in /usr/bin. See 
https://github.com/github/hub/issues/855 for an example.

Thanks a lot,

David Rodríguez.

On Tue, 21 Apr 2015 18:37:29 +0000, David Rodríguez wrote:
...

This causes issues with Ruby git hooks, because Ruby version managers 
rely on custom settings in PATH to select the Ruby executable,

Even if git wouldn't modify PATH this is still a broken way to do that.
What ruby to execute a hook with is a property of the hook, not of the
user context invoking it.

Andreas

-- 
"Totally trivial. Famous last words."
From: Linus Torvalds <torvalds@*.org>
Date: Fri, 22 Jan 2010 07:29:21 -0800

On 22/04/15 02:47, Andreas Krey wrote:

On Tue, 21 Apr 2015 18:37:29 +0000, David Rodríguez wrote:
...

quoted

This causes issues with Ruby git hooks, because Ruby version managers
rely on custom settings in PATH to select the Ruby executable,

Even if git wouldn't modify PATH this is still a broken way to do that.
What ruby to execute a hook with is a property of the hook, not of the
user context invoking it.

Andreas

I probably shouldn't have mentioned Ruby version managers since they are 
not directly related to this issue. I'll try to elaborate on the issue:

* User is relying on a custom path to select their Ruby version. For 
example, let's say the first folder in path is "~/.rubies/2.2.2/bin".
* User runs "/usr/bin/git commit" and a pre-commit hook is triggered.
* The pre-commit hook starts with "#!/us/bin/env ruby" to select the 
Ruby to be used in the hook, but since the path has been changed by 
"/usr/bin/git", the selected ruby will be "/usr/bin/ruby" and not 
"~/.rubies/2.2.2/bin/ruby" as the user would expect.

What's the proper way to do whatever you're saying is done in "a broken 
way"?

On Wed, 22 Apr 2015 08:36:00 +0000, David Rodríguez wrote:
...

* User is relying on a custom path to select their Ruby version. For 
example, let's say the first folder in path is "~/.rubies/2.2.2/bin".
* User runs "/usr/bin/git commit" and a pre-commit hook is triggered.
* The pre-commit hook starts with "#!/us/bin/env ruby" to select the 
Ruby to be used in the hook,

Yes...but shouldn't the hook itself know which ruby version it needs?

After all, if I go into that directory with another ruby setup in my
PATH, the hook should still work, and presumably that requires that
the hook itself selects its version, and not the user's context.

Andreas

-- 
"Totally trivial. Famous last words."
From: Linus Torvalds <torvalds@*.org>
Date: Fri, 22 Jan 2010 07:29:21 -0800

On Wed, Apr 22, 2015 at 05:31:09PM +0200, Andreas Krey wrote:

On Wed, 22 Apr 2015 08:36:00 +0000, David Rodríguez wrote:
...

quoted

* User is relying on a custom path to select their Ruby version. For
example, let's say the first folder in path is "~/.rubies/2.2.2/bin".
* User runs "/usr/bin/git commit" and a pre-commit hook is triggered.
* The pre-commit hook starts with "#!/us/bin/env ruby" to select the
Ruby to be used in the hook,

Yes...but shouldn't the hook itself know which ruby version it needs?

After all, if I go into that directory with another ruby setup in my
PATH, the hook should still work, and presumably that requires that
the hook itself selects its version, and not the user's context.

More generally, #!/usr/bin/env ruby is saying, "I want whatever ruby the
user chooses."  If you want a ruby that has certain gems, or certain
features (e.g. Array#to_h), then that's not what you want.
#!/usr/bin/env ruby is basically only safe if you're willing to accept
any potential version that might show up.

You can use a multiline shebang[0] if you need to execute shell code to
make the decision at runtime, such as if you need to use $HOME in the
path to your ruby, or select from multiple different options.

[0] http://rosettacode.org/wiki/Multiline_shebang
-- 
brian m. carlson / brian with sandals: Houston, Texas, US
+1 832 623 2791 | http://www.crustytoothpaste.net/~bmc | My opinion only
OpenPGP: RSA v4 4096b: 88AC E9B2 9196 305B A994 7552 F1BA 225C 0223 B187

On 22/04/15 14:02, brian m. carlson wrote:

"I want whatever ruby the
user chooses."

This is exactly what I want. The problem is that git overrides the 
user's choice by prepending /usr/bin to the path and thus making 
/usr/bin/env choose system's ruby version. Which is almost always not 
the Ruby the user chose.