[FILE] GNU BIT

               BIT - a little bit like SCM
   

BIT is a training exercise in shell programming and is the result of my attempts to wrap my head around GIT's inner working. BIT's command line interface should be very familiar to anyone who worked with other(tm) SCM tools before. I try to not depend on custom GIT features. BIT uses the off-the-shelf GIT core tools distributed by Linus. This means that BIT has about 2% of the features of Cogito. Also, it has about 0.1% of the user base of Cogito, so its probably very broken and I really don't recommend using it.

You can obtain BIT from the following GIT repository:

http://nil.ics.uci.edu/~gal/public/bit

You can use the GIT core utilities to pull and check-out BIT:

init-db
curl http://nil.ics.uci.edu/~gal/public/bit/HEAD > .git/HEAD
http-pull -a `cat .git/HEAD` \
    http://nil.ics.uci.edu/~gal/public/bit
read-tree `cat .git/HEAD`
checkout-cache -f -a

Naturally, you can also use BIT to pull the current sources, which is much simpler:

bit clone http://nil.ics.uci.edu/~gal/public/bit

This will create a directory "bit", pull the latest sources and perform a check-out for you.

INSTALLATION

Put "bit" anywhere in your search path. Its only a single bash script. It requires a link "bit-resolve" to itself and the (soft) link should reside in the same directory as "bit" itself. "bit" acts as merge script when invoked through that link.

At this point, BIT's functionality is minimal. It does what I need it for. I will obviously add more commands as we go along, but I won't touch things like tags and stuff like that until Linus' makes up his mind how to do it *RIGHT*.

BASIC CONCEPTS

- BIT always checks out all files in your repository and it does so
  automatically. In other words, there is no "bit co" command. Not
  everyone will like this, but I do.
- You can't seek around in a repository. Checked-out files always
  match the HEAD revision. You can diff files against older versions,
  but if you want to check out an older version, you will have to
  clone the repository (see below).
  
TRACKING SOMEONE ELSE'S TREE  
  
$ bit clone http://www.kernel.org/pub/linux/kernel/people/torvalds/git.git/

(Note: Don't forget the '/' at the end, otherwise http-pull won't work.)

This command pulls Linus' latest GIT tree to a local repository "git.git".
You can change the latter by giving clone an additional argument.
  
$ bit clone http://www.kernel.org/pub/linux/kernel/people/torvalds/git.git/ \
    git-trunk
  
Once you have a copy of the remote repository, you can check whether there
are new changesets in the remote repository that you haven't seen yet:
  
$ bit changes -R \
      http://www.kernel.org/pub/linux/kernel/people/torvalds/git.git/
      
If you see any changes, you can merge them into your own tree:
  
$ bit pull http://www.kernel.org/pub/linux/kernel/people/torvalds/git.git/
      
BRANCHING

Now lets assume you want to work on an extension to GIT. For this, we will
clone the repository:
  
$ bit clone git-trunk git-bit
  
This will create a copy of the git-trunk repository and name it "git-bit".
The object directory is shared (using a soft link), which has the nice
benefit that once you run "bit pull" on one of the repositories, the
other one will be able to merge changes without any network traffic
(except for reading the current HEAD).
  
Lets say we make some changes to sha1_file.c and want to commit it to
our local repository "git-bit":
  
... edit sha1_file.c ...
  
In case we already forgot what file we edited, "bit pending" will tells us:
  
$ bit pending
sha1_file.c
  
Just in case we still can remember what we changed, there is "bit diffs",
which shows a diff to the current HEAD or any other version of our 
tree.
  
$ bit diffs
--- 28ad1598e54200ca8ee1261ed7beb4e31e20b2f1/sha1_file.c
+++ sha1_file.c