Re: checkout extra files

From: Junio C Hamano <gitster@pobox.com>
Date: Sep 7, 2012, 20:49 UTC
Message-ID: <7vk3w5woc4.fsf@alter.siamese.dyndns.org>
In-Reply-To: <7v8vcpdat2.fsf@alter.siamese.dyndns.org>

Junio C Hamano <gitster@pobox.com> writes:

Show 20 quoted lines

> But that is not what is happening at all.  What goes on is far
> simpler than that.
>
>  - the shell sees '*', matches it against working tree files, to
>    obtain "f1" and "f2";
>
>  - the shell tells "git" to "checkout e6f935e -- f1 f2";
>
>  - "git" looks into the tree of e6f935e to find paths that match
>    "f1" and "f2".
>
> When "git" is run by the shell in the last step, it has _no_ clue
> that the end user typed "*" from the shell.  It only sees "f1" and
> "f2" on the command line.  There is no "set T" to be intersected
> with "set W", so stop thinking in those terms, and you will be fine.
>
> Now the question is, _you_ will be fine, but can the documentation 
> be updated in such a way so that it will help _others_ to also stop
> thinking about "intersection between set W and set T"?  I do not
> have a good answer to that.

Let's do this. I do not want a shell tutorial in "git checkout" documentation, but this would fit better in the documentation for the CLI convention.

-- >8 -- gitcli: contrast wildcard given to shell and to git

People who are not used to working with shell may intellectually understand how the command line argument is massaged by the shell but still have a hard time visualizing the difference between letting the shell expand fileglobs and having Git see the fileglob to use as a pathspec.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 Documentation/gitcli.txt | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git c/Documentation/gitcli.txt w/Documentation/gitcli.txt
index ea17f7a..220621b 100644
--- c/Documentation/gitcli.txt
+++ w/Documentation/gitcli.txt
@@ -38,6 +38,22 @@ arguments.  Here are the rules:
    you have to say either `git diff HEAD --` or `git diff -- HEAD` to
    disambiguate.
 
+ * Many commands allow wildcards in paths, but you need to protect
+them from getting globbed by the shell.  These two mean different things:
++
+--------------------------------
+$ git checkout -- *.c
+$ git checkout -- \*.c
+--------------------------------
++
+The former lets your shell expand the fileglob, and you are asking
+the dot-C files in your working tree to be overwritten with the version
+in the index.  The latter passes the `*.c` to Git, and you are asking
+the paths in the index that match the pattern to be checked out to your
+working tree.  After running `git add hello.c; rm hello.c`, you will _not_
+see `hello.c` in your working tree with the former, but with the latter
+you will.
+
 When writing a script that is expected to handle random user-input, it is
 a good practice to make it explicit which arguments are which by placing
 disambiguating `--` at appropriate places.