Subject: Re: gitignore: how to exclude a directory tree from being ignored

From: Johannes Sixt <[email-masked]>
Date: Thu, 01 Oct 2009 17:25:15 +0200

Peter schrieb:
>>> 1) I can't have just one .gitignore file in the root dir, if I want to
>>> _recursively_ inverse the exclude pattern for a sub dir tree.
>>>     
>>
>> No, it's not the inversion of the pattern, but the slash (if it is not at
>> the end) that makes the pattern non-recursive.
>>
>>   
> from the gitignore manpage:
>>> If the pattern ends with a slash, it is removed for the purpose of
> the following description, but it would only find a match with a
> directory. In other words, foo/ will match a directory foo and paths
> underneath it, but will not match a regular file or a symbolic link foo
> (this is consistent with the way how pathspec works in general in git). <<
> 
> Doesn't this mean, that if I say:
> vendor/
> matches the directory and ( recursively ) the paths underneath it.?

The paragraph you are citing is talking about *what* the pattern matches,
but it says nothing about *where* the pattern matches.

When I was saying "recursively", then I was refering to the "where"
aspect, not the "what" aspect.

If you have directories

   src/bar/vendor/
   src/foo/bar/vendor/
   src/vendor/

and you have the file src/.gitignore with the single pattern

   vendor/

then it applies to recursively ("where") these directories:

   src/bar/vendor/
   src/foo/bar/vendor/
   src/vendor/

and everything ("what") below them.

But if the same src/.gitignore has only this pattern:

   bar/vendor/

then it will not match ("where") recursively and only apply to

   src/bar/vendor/

and everything ("what") below it, but will not apply to

   src/foo/bar/vendor/

> And, consequently:
> !vendor/
> inverse the exclusion for vendor ( that is: include ) and everything
> that is contained in it ? ( This is obviously not the case, but this is
> what I would expect )

You should update your expectations. ;-)

You think that git starts with the .gitignore files, and somehow applies
the rules that it finds to all files (perhaps recursively).

But it does not work like this; rather it is in the oppsite direction: git
starts with a file name, and then checks the rules in the .gitignore files
that it has available.

For example, take the path "src/vendor/foo.exe". git finds the file
src/.gitignore and there it sees the pattern "*.exe". The pattern matches,
and so git obeys the rule (ignores the file). But the pattern "!vendor/"
does not match (because the path ends with "foo.exe", not "vendor").

Before git had seen the path "src/vendor/foo.exe", it had already seen
"src/vendor". This time the pattern "!vendor/" did match (because the name
is identical *and* it is a directory, as per the cited paragraph) and git
obeyed the rule (which was not to ignore the directory).

-- Hannes