Updated git HOWTO for kernel hackers

Things in git-land are moving at lightning speed, and usability has improved a lot since my post a month ago: http://lkml.org/lkml/2005/5/26/11

1) installing git

git requires bootstrapping, since you must have git installed in order to check out git.git (git repo), and linux-2.6.git (kernel repo). I have put together a bootstrap tarball of today's git repository.

Download tarball from: http://www.kernel.org/pub/linux/kernel/people/jgarzik/git-20050622.tar.bz2

tarball build-deps:  zlib, libcurl, libcrypto (openssl)

install tarball:  unpack && make && sudo make prefix=/usr/local install

jgarzik helper scripts, not in official git distribution: http://www.kernel.org/pub/linux/kernel/people/jgarzik/git-new-branch http://www.kernel.org/pub/linux/kernel/people/jgarzik/git-changes-script

After reading the rest of this document, come back and update your copy of git to the latest: rsync://rsync.kernel.org/pub/scm/linux/kernel/git/torvalds/git.git

2) download a linux kernel tree for the very first time

$ mkdir -p linux-2.6/.git
$ cd linux-2.6
$ rsync -a --delete --verbose --stats --progress \
rsync://rsync.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git/ 
\          <- word-wrapped backslash; sigh
     .git/

3) update local kernel tree to latest 2.6.x upstream ("fast-forward merge")

$ cd linux-2.6 $ git-pull-script \ rsync://rsync.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git

4) check out files from the git repository into the working directory

$ git checkout -f

5) check in your own modifications (e.g. do some hacking, or apply a patch)

# go to repo $ cd linux-2.6

# make some modifications $ patch -sp1 < /tmp/my.patch $ diffstat -p1 < /tmp/my.patch

# NOTE: add '--add' and/or '--remove' if files were added or removed $ git-update-cache <list of all files changed>

# check in changes $ git commit

6) List all changes in working dir, in diff format.

$ git-diff-cache -p HEAD

7) List all changesets (i.e. show each cset's description text) in local 
branch of local tree, that are not present in remote tree.

$ cd my-kernel-tree-2.6 $ git-changes-script -L ../linux-2.6 | less

8) List all changesets:

$ git-whatchanged

9) apply all patches in a Berkeley mbox-format file

First, download and add to your PATH Linus's git tools: rsync://rsync.kernel.org/pub/scm/linux/kernel/git/torvalds/git-tools.git

$ cd my-kernel-tree-2.6 $ dotest /path/to/mbox # yes, Linus has no taste in naming scripts

10) don't forget to download tags from time to time.

git-pull-script only downloads sha1-indexed object data, and the requested remote head. This misses updates to the .git/refs/tags/ and .git/refs/heads directories. It is advisable to update your kernel .git directories periodically with a full rsync command, to make sure you got everything:

$ cd linux-2.6
$ rsync -a --delete --verbose --stats --progress \
rsync://rsync.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git/
\          <- word-wrapped backslash; sigh
     .git/

11) list all branches, such as those found in my netdev-2.6 or 
libata-dev trees.

Download
rsync://rsync.kernel.org/pub/scm/linux/kernel/git/jgarzik/netdev-2.6.git
	or
rsync://rsync.kernel.org/pub/scm/linux/kernel/git/jgarzik/libata-dev.git

$ cd netdev-2.6 $ ls .git/refs/heads/

{ these are the current netdev-2.6 branches }

12) make desired branch current in working directory

$ git checkout -f $branch

13) create a new branch, and make it current

$ cp .git/refs/heads/master .git/refs/heads/my-new-branch-name $ git checkout -f my-new-branch-name

14) examine which branch is current

$ ls -l .git/HEAD

15) undo all local modifications (same as checkout):

$ git checkout -f

16) obtain a diff between current branch, and master branch

In most trees WITH BRANCHES, .git/refs/heads/master contains the current 'vanilla' upstream tree, for easy diffing and merging. (in trees without branches, 'master' simply contains your latest changes)

$ git-diff-tree -p master HEAD