Kernel Hackers Guide to git (v3)

Jeff Garzik
2005-06-25T05:14:01Z

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See attached.

An HTML version is also available at http://linux.yyz.us/git-howto.html

Jeff

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Kernel Hackers' Guide to git

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 a recent 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

$ git clone \
rsync://rsync.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git \
linux-2.6
$ cd linux-2.6
$ rsync -a --delete --verbose --stats --progress \
rsync://rsync.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git/ \
.git/

NOTE: The kernel tree is very large. This constitutes downloading
several hundred megabytes of data.

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
$ vi drivers/net/sk98lin/skdim.c

# NOTE: add '--add' and/or '--remove' if files were added or removed
$ git-update-cache

# check in changes
$ git commit

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

$ git diff

7) Obtain summary of all changes in working dir

$ git status

8) 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

9) List all changesets:

$ git log

10) 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

11) 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/ \
.git/

12) list all branches

$ ls .git/refs/heads/

13) make desired branch current in working directory

$ git checkout -f $branch

14) 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

15) examine which branch is current

$ ls -l .git/HEAD

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

$ git checkout -f

17) 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 master..HEAD