I recently asked about keyword expansion in Git and I'm willing to accept the design not to really support this idea in Git.
For better or worse, the project I'm working on at the moment requires SVN keyword expansion like this:
svn propset svn:keywords "Id" expl3.dtx
to keep this string up-to-date:
$Id: expl3.dtx 803 2008-09-11 14:01:58Z will $
But I would quite like to use Git to do my version control. Unfortunately, git-svn doesn't support this, according to the docs:
"We ignore all SVN properties except svn:executable"
But it doesn't seem too tricky to have this keyword stuff emulated by a couple of pre/post commit hooks. Am I the first person to want this? Does anyone have some code to do this?
No interaction between them. Just ignore the . git folder for SVN and the . svn folder for Git and you should be fine.
Git has the advantage that it's MUCH better suited if some developers are not always connected to the master repository. Also, it's much faster than SVN. And from what I hear, branching and merging support is a lot better (which is to be expected, as these are the core reasons it was written).
git svn is a git command that allows using git to interact with Subversion repositories. git svn is part of git, meaning that is NOT a plugin but actually bundled with your git installation. SourceTree also happens to support this command so you can use it with your usual workflow.
# Clone a repo with standard SVN directory layout (like git clone): git svn clone http://svn.example.com/project --stdlayout --prefix svn/ # Or, if the repo uses a non-standard directory layout: git svn clone http://svn.example.com/project -T tr -b branch -t tag --prefix svn/ # View all branches and tags you have ...
What's going on here: Git is optimized to switch between branches as quickly as possible. In particular, git checkout
is designed to not touch any files that are identical in both branches.
Unfortunately, RCS keyword substitution breaks this. For example, using $Date$
would require git checkout
to touch every file in the tree when switching branches. For a repository the size of the Linux kernel, this would bring everything to a screeching halt.
In general, your best bet is to tag at least one version:
$ git tag v0.5.whatever
...and then call the following command from your Makefile:
$ git describe --tags v0.5.15.1-6-g61cde1d
Here, git is telling me that I'm working on an anonymous version 6 commits past v0.5.15.1, with an SHA1 hash beginning with g61cde1d
. If you stick the output of this command into a *.h
file somewhere, you're in business, and will have no problem linking the released software back to the source code. This is the preferred way of doing things.
If you can't possibly avoid using RCS keywords, you may want to start with this explanation by Lars Hjemli. Basically, $Id$
is pretty easy, and you if you're using git archive
, you can also use $Format$
.
But, if you absolutely cannot avoid RCS keywords, the following should get you started:
git config filter.rcs-keyword.clean 'perl -pe "s/\\\$Date[^\\\$]*\\\$/\\\$Date\\\$/"' git config filter.rcs-keyword.smudge 'perl -pe "s/\\\$Date[^\\\$]*\\\$/\\\$Date: `date`\\\$/"' echo '$Date$' > test.html echo 'test.html filter=rcs-keyword' >> .gitattributes git add test.html .gitattributes git commit -m "Experimental RCS keyword support for git" rm test.html git checkout test.html cat test.html
On my system, I get:
$Date: Tue Sep 16 10:15:02 EDT 2008$
If you have trouble getting the shell escapes in the smudge
and clean
commands to work, just write your own Perl scripts for expanding and removing RCS keywords, respectively, and use those scripts as your filter.
Note that you really don't want to do this for more files than absolutely necessary, or git will lose most of its speed.
Unfortunately, RCS keyword substitution breaks this. For example, using $Date$ would require git checkout to touch every file in the tree when switching branches.
That is not true. $Date$ etc. expand to the value which holds at checkin time. That is much more useful anyway. So it doesn't change on other revisions or branches, unless the file is actually re-checked-in. From the RCS manual:
$Date$ The date and time the revision was checked in. With -zzone a numeric time zone offset is appended; otherwise, the date is UTC.
This also means that the suggested answer above, with the rcs-keyword.smudge filter, is incorrect. It inserts the time/date of the checkout, or whatever it is that causes it to run.
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