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Git User's Manual (for version 1.5.1 or newer)
______________________________________________
+
+Git is a fast distributed revision control system.
+
This manual is designed to be readable by someone with basic unix
command-line skills, but no previous knowledge of git.
Examples
--------
+[[counting-commits-on-a-branch]]
+Counting the number of commits on a branch
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Suppose you want to know how many commits you've made on "mybranch"
+since it diverged from "origin":
+
+-------------------------------------------------
+$ git log --pretty=oneline origin..mybranch | wc -l
+-------------------------------------------------
+
+Alternatively, you may often see this sort of thing done with the
+lower-level command gitlink:git-rev-list[1], which just lists the SHA1's
+of all the given commits:
+
+-------------------------------------------------
+$ git rev-list origin..mybranch | wc -l
+-------------------------------------------------
+
[[checking-for-equal-branches]]
Check whether two branches point at the same history
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Which shows that e05db0fd is reachable from itself, from v1.5.0-rc1, and
from v1.5.0-rc2, but not from v1.5.0-rc0.
+[[showing-commits-unique-to-a-branch]]
+Showing commits unique to a given branch
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Suppose you would like to see all the commits reachable from the branch
+head named "master" but not from any other head in your repository.
+
+We can list all the heads in this repository with
+gitlink:git-show-ref[1]:
+
+-------------------------------------------------
+$ git show-ref --heads
+bf62196b5e363d73353a9dcf094c59595f3153b7 refs/heads/core-tutorial
+db768d5504c1bb46f63ee9d6e1772bd047e05bf9 refs/heads/maint
+a07157ac624b2524a059a3414e99f6f44bebc1e7 refs/heads/master
+24dbc180ea14dc1aebe09f14c8ecf32010690627 refs/heads/tutorial-2
+1e87486ae06626c2f31eaa63d26fc0fd646c8af2 refs/heads/tutorial-fixes
+-------------------------------------------------
+
+We can get just the branch-head names, and remove "master", with
+the help of the standard utilities cut and grep:
+
+-------------------------------------------------
+$ git show-ref --heads | cut -d' ' -f2 | grep -v '^refs/heads/master'
+refs/heads/core-tutorial
+refs/heads/maint
+refs/heads/tutorial-2
+refs/heads/tutorial-fixes
+-------------------------------------------------
+
+And then we can ask to see all the commits reachable from master
+but not from these other heads:
+
+-------------------------------------------------
+$ gitk master --not $( git show-ref --heads | cut -d' ' -f2 |
+ grep -v '^refs/heads/master' )
+-------------------------------------------------
+
+Obviously, endless variations are possible; for example, to see all
+commits reachable from some head but not from any tag in the repository:
+
+-------------------------------------------------
+$ gitk $( git show-ref --heads ) --not $( git show-ref --tags )
+-------------------------------------------------
+
+(See gitlink:git-rev-parse[1] for explanations of commit-selecting
+syntax such as `--not`.)
+
[[making-a-release]]
Creating a changelog and tarball for a software release
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
and then he just cut-and-pastes the output commands after verifying that
they look OK.
+Finding commits referencing a file with given content
+-----------------------------------------------------
+
+Somebody hands you a copy of a file, and asks which commits modified a
+file such that it contained the given content either before or after the
+commit. You can find out with this:
+
+-------------------------------------------------
+$ git log --raw -r --abbrev=40 --pretty=oneline -- filename |
+ grep -B 1 `git hash-object filename`
+-------------------------------------------------
+
+Figuring out why this works is left as an exercise to the (advanced)
+student. The gitlink:git-log[1], gitlink:git-diff-tree[1], and
+gitlink:git-hash-object[1] man pages may prove helpful.
+
[[Developing-with-git]]
Developing with git
===================
the first line on the Subject line and the rest of the commit in the
body.
+[[ignoring-files]]
+Ignoring files
+--------------
+
+A project will often generate files that you do 'not' want to track with git.
+This typically includes files generated by a build process or temporary
+backup files made by your editor. Of course, 'not' tracking files with git
+is just a matter of 'not' calling "`git add`" on them. But it quickly becomes
+annoying to have these untracked files lying around; e.g. they make
+"`git add .`" and "`git commit -a`" practically useless, and they keep
+showing up in the output of "`git status`", etc.
+
+Git therefore provides "exclude patterns" for telling git which files to
+actively ignore. Exclude patterns are thoroughly explained in the
+"Exclude Patterns" section of the gitlink:git-ls-files[1] manual page,
+but the heart of the concept is simply a list of files which git should
+ignore. Entries in the list may contain globs to specify multiple files,
+or may be prefixed by "`!`" to explicitly include (un-ignore) a previously
+excluded (ignored) file (i.e. later exclude patterns override earlier ones).
+The following example should illustrate such patterns:
+
+-------------------------------------------------
+# Lines starting with '#' are considered comments.
+# Ignore foo.txt.
+foo.txt
+# Ignore (generated) html files,
+*.html
+# except foo.html which is maintained by hand.
+!foo.html
+# Ignore objects and archives.
+*.[oa]
+-------------------------------------------------
+
+The next question is where to put these exclude patterns so that git can
+find them. Git looks for exclude patterns in the following files:
+
+`.gitignore` files in your working tree:::
+ You may store multiple `.gitignore` files at various locations in your
+ working tree. Each `.gitignore` file is applied to the directory where
+ it's located, including its subdirectories. Furthermore, the
+ `.gitignore` files can be tracked like any other files in your working
+ tree; just do a "`git add .gitignore`" and commit. `.gitignore` is
+ therefore the right place to put exclude patterns that are meant to
+ be shared between all project participants, such as build output files
+ (e.g. `\*.o`), etc.
+`.git/info/exclude` in your repo:::
+ Exclude patterns in this file are applied to the working tree as a
+ whole. Since the file is not located in your working tree, it does
+ not follow push/pull/clone like `.gitignore` can do. This is therefore
+ the place to put exclude patterns that are local to your copy of the
+ repo (i.e. 'not' shared between project participants), such as
+ temporary backup files made by your editor (e.g. `\*~`), etc.
+The file specified by the `core.excludesfile` config directive:::
+ By setting the `core.excludesfile` config directive you can tell git
+ where to find more exclude patterns (see gitlink:git-config[1] for
+ more information on configuration options). This config directive
+ can be set in the per-repo `.git/config` file, in which case the
+ exclude patterns will apply to that repo only. Alternatively, you
+ can set the directive in the global `~/.gitconfig` file to apply
+ the exclude pattern to all your git repos. As with the above
+ `.git/info/exclude` (and, indeed, with git config directives in
+ general), this directive does not follow push/pull/clone, but remain
+ local to your repo(s).
+
+[NOTE]
+In addition to the above alternatives, there are git commands that can take
+exclude patterns directly on the command line. See gitlink:git-ls-files[1]
+for an example of this.
+
[[how-to-merge]]
How to merge
------------
the original mailbox, with authorship and commit log message each
taken from the message containing each patch.
-[[setting-up-a-public-repository]]
-Setting up a public repository
-------------------------------
+[[public-repositories]]
+Public git repositories
+-----------------------
-Another way to submit changes to a project is to simply tell the
-maintainer of that project to pull from your repository, exactly as
-you did in the section "<<getting-updates-with-git-pull, Getting
-updates with git pull>>".
+Another way to submit changes to a project is to tell the maintainer of
+that project to pull the changes from your repository using git-pull[1].
+In the section "<<getting-updates-with-git-pull, Getting updates with
+git pull>>" we described this as a way to get updates from the "main"
+repository, but it works just as well in the other direction.
-If you and maintainer both have accounts on the same machine, then
-then you can just pull changes from each other's repositories
-directly; note that all of the commands (gitlink:git-clone[1],
-git-fetch[1], git-pull[1], etc.) that accept a URL as an argument
-will also accept a local directory name; so, for example, you can
-use
+If you and the maintainer both have accounts on the same machine, then
+you can just pull changes from each other's repositories directly;
+commands that accepts repository URLs as arguments will also accept a
+local directory name:
-------------------------------------------------
$ git clone /path/to/repository
$ git pull /path/to/other/repository
-------------------------------------------------
-If this sort of setup is inconvenient or impossible, another (more
-common) option is to set up a public repository on a public server.
-This also allows you to cleanly separate private work in progress
-from publicly visible work.
+However, the more common way to do this is to maintain a separate public
+repository (usually on a different host) for others to pull changes
+from. This is usually more convenient, and allows you to cleanly
+separate private work in progress from publicly visible work.
You will continue to do your day-to-day work in your personal
repository, but periodically "push" changes from your personal
| they push V
their public repo <------------------- their repo
-Now, assume your personal repository is in the directory ~/proj. We
-first create a new clone of the repository:
+[[setting-up-a-public-repository]]
+Setting up a public repository
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Assume your personal repository is in the directory ~/proj. We
+first create a new clone of the repository and tell git-daemon that it
+is meant to be public:
-------------------------------------------------
$ git clone --bare ~/proj proj.git
+$ touch proj.git/git-daemon-export-ok
-------------------------------------------------
The resulting directory proj.git contains a "bare" git repository--it is
-just the contents of the ".git" directory, without a checked-out copy of
-a working directory.
+just the contents of the ".git" directory, without any files checked out
+around it.
Next, copy proj.git to the server where you plan to host the
public repository. You can use scp, rsync, or whatever is most
convenient.
-If somebody else maintains the public server, they may already have
-set up a git service for you, and you may skip to the section
+[[exporting-via-git]]
+Exporting a git repository via the git protocol
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+This is the preferred method.
+
+If someone else administers the server, they should tell you what
+directory to put the repository in, and what git:// url it will appear
+at. You can then skip to the section
"<<pushing-changes-to-a-public-repository,Pushing changes to a public
repository>>", below.
-Otherwise, the following sections explain how to export your newly
-created public repository:
+Otherwise, all you need to do is start gitlink:git-daemon[1]; it will
+listen on port 9418. By default, it will allow access to any directory
+that looks like a git directory and contains the magic file
+git-daemon-export-ok. Passing some directory paths as git-daemon
+arguments will further restrict the exports to those paths.
+
+You can also run git-daemon as an inetd service; see the
+gitlink:git-daemon[1] man page for details. (See especially the
+examples section.)
[[exporting-via-http]]
Exporting a git repository via http
------------------------------------
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The git protocol gives better performance and reliability, but on a
host with a web server set up, http exports may be simpler to set up.
(For an explanation of the last two lines, see
gitlink:git-update-server-info[1], and the documentation
-link:hooks.txt[Hooks used by git].)
+link:hooks.html[Hooks used by git].)
Advertise the url of proj.git. Anybody else should then be able to
clone or pull from that url, for example with a commandline like:
for a slightly more sophisticated setup using WebDAV which also
allows pushing over http.)
-[[exporting-via-git]]
-Exporting a git repository via the git protocol
------------------------------------------------
-
-This is the preferred method.
-
-For now, we refer you to the gitlink:git-daemon[1] man page for
-instructions. (See especially the examples section.)
-
[[pushing-changes-to-a-public-repository]]
Pushing changes to a public repository
---------------------------------------
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-Note that the two techniques outline above (exporting via
+Note that the two techniques outlined above (exporting via
<<exporting-via-http,http>> or <<exporting-via-git,git>>) allow other
maintainers to fetch your latest changes, but they do not allow write
access, which you will need to update the public repository with the
[[setting-up-a-shared-repository]]
Setting up a shared repository
-------------------------------
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Another way to collaborate is by using a model similar to that
commonly used in CVS, where several developers with special rights
all push to and pull from a single shared repository. See
-link:cvs-migration.txt[git for CVS users] for instructions on how to
+link:cvs-migration.html[git for CVS users] for instructions on how to
set this up.
+However, while there is nothing wrong with git's support for shared
+repositories, this mode of operation is not generally recommended,
+simply because the mode of collaboration that git supports--by
+exchanging patches and pulling from public repositories--has so many
+advantages over the central shared repository:
+
+ - Git's ability to quickly import and merge patches allows a
+ single maintainer to process incoming changes even at very
+ high rates. And when that becomes too much, git-pull provides
+ an easy way for that maintainer to delegate this job to other
+ maintainers while still allowing optional review of incoming
+ changes.
+ - Since every developer's repository has the same complete copy
+ of the project history, no repository is special, and it is
+ trivial for another developer to take over maintenance of a
+ project, either by mutual agreement, or because a maintainer
+ becomes unresponsive or difficult to work with.
+ - The lack of a central group of "committers" means there is
+ less need for formal decisions about who is "in" and who is
+ "out".
+
[[setting-up-gitweb]]
-Allow web browsing of a repository
-----------------------------------
+Allowing web browsing of a repository
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The gitweb cgi script provides users an easy way to browse your
project's files and history without having to install git; see the file
Examples
--------
-TODO: topic branches, typical roles as in everyday.txt, ?
+[[maintaining-topic-branches]]
+Maintaining topic branches for a Linux subsystem maintainer
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+This describes how Tony Luck uses git in his role as maintainer of the
+IA64 architecture for the Linux kernel.
+
+He uses two public branches:
+
+ - A "test" tree into which patches are initially placed so that they
+ can get some exposure when integrated with other ongoing development.
+ This tree is available to Andrew for pulling into -mm whenever he
+ wants.
+
+ - A "release" tree into which tested patches are moved for final sanity
+ checking, and as a vehicle to send them upstream to Linus (by sending
+ him a "please pull" request.)
+
+He also uses a set of temporary branches ("topic branches"), each
+containing a logical grouping of patches.
+
+To set this up, first create your work tree by cloning Linus's public
+tree:
+
+-------------------------------------------------
+$ git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6.git work
+$ cd work
+-------------------------------------------------
+
+Linus's tree will be stored in the remote branch named origin/master,
+and can be updated using gitlink:git-fetch[1]; you can track other
+public trees using gitlink:git-remote[1] to set up a "remote" and
+git-fetch[1] to keep them up-to-date; see <<repositories-and-branches>>.
+
+Now create the branches in which you are going to work; these start out
+at the current tip of origin/master branch, and should be set up (using
+the --track option to gitlink:git-branch[1]) to merge changes in from
+Linus by default.
+
+-------------------------------------------------
+$ git branch --track test origin/master
+$ git branch --track release origin/master
+-------------------------------------------------
+
+These can be easily kept up to date using gitlink:git-pull[1]
+
+-------------------------------------------------
+$ git checkout test && git pull
+$ git checkout release && git pull
+-------------------------------------------------
+
+Important note! If you have any local changes in these branches, then
+this merge will create a commit object in the history (with no local
+changes git will simply do a "Fast forward" merge). Many people dislike
+the "noise" that this creates in the Linux history, so you should avoid
+doing this capriciously in the "release" branch, as these noisy commits
+will become part of the permanent history when you ask Linus to pull
+from the release branch.
+
+A few configuration variables (see gitlink:git-config[1]) can
+make it easy to push both branches to your public tree. (See
+<<setting-up-a-public-repository>>.)
+
+-------------------------------------------------
+$ cat >> .git/config <<EOF
+[remote "mytree"]
+ url = master.kernel.org:/pub/scm/linux/kernel/git/aegl/linux-2.6.git
+ push = release
+ push = test
+EOF
+-------------------------------------------------
+
+Then you can push both the test and release trees using
+gitlink:git-push[1]:
+
+-------------------------------------------------
+$ git push mytree
+-------------------------------------------------
+
+or push just one of the test and release branches using:
+
+-------------------------------------------------
+$ git push mytree test
+-------------------------------------------------
+
+or
+
+-------------------------------------------------
+$ git push mytree release
+-------------------------------------------------
+
+Now to apply some patches from the community. Think of a short
+snappy name for a branch to hold this patch (or related group of
+patches), and create a new branch from the current tip of Linus's
+branch:
+
+-------------------------------------------------
+$ git checkout -b speed-up-spinlocks origin
+-------------------------------------------------
+
+Now you apply the patch(es), run some tests, and commit the change(s). If
+the patch is a multi-part series, then you should apply each as a separate
+commit to this branch.
+
+-------------------------------------------------
+$ ... patch ... test ... commit [ ... patch ... test ... commit ]*
+-------------------------------------------------
+
+When you are happy with the state of this change, you can pull it into the
+"test" branch in preparation to make it public:
+
+-------------------------------------------------
+$ git checkout test && git pull . speed-up-spinlocks
+-------------------------------------------------
+
+It is unlikely that you would have any conflicts here ... but you might if you
+spent a while on this step and had also pulled new versions from upstream.
+
+Some time later when enough time has passed and testing done, you can pull the
+same branch into the "release" tree ready to go upstream. This is where you
+see the value of keeping each patch (or patch series) in its own branch. It
+means that the patches can be moved into the "release" tree in any order.
+
+-------------------------------------------------
+$ git checkout release && git pull . speed-up-spinlocks
+-------------------------------------------------
+
+After a while, you will have a number of branches, and despite the
+well chosen names you picked for each of them, you may forget what
+they are for, or what status they are in. To get a reminder of what
+changes are in a specific branch, use:
+
+-------------------------------------------------
+$ git log linux..branchname | git-shortlog
+-------------------------------------------------
+
+To see whether it has already been merged into the test or release branches
+use:
+
+-------------------------------------------------
+$ git log test..branchname
+-------------------------------------------------
+
+or
+
+-------------------------------------------------
+$ git log release..branchname
+-------------------------------------------------
+
+(If this branch has not yet been merged you will see some log entries.
+If it has been merged, then there will be no output.)
+
+Once a patch completes the great cycle (moving from test to release,
+then pulled by Linus, and finally coming back into your local
+"origin/master" branch) the branch for this change is no longer needed.
+You detect this when the output from:
+
+-------------------------------------------------
+$ git log origin..branchname
+-------------------------------------------------
+
+is empty. At this point the branch can be deleted:
+
+-------------------------------------------------
+$ git branch -d branchname
+-------------------------------------------------
+
+Some changes are so trivial that it is not necessary to create a separate
+branch and then merge into each of the test and release branches. For
+these changes, just apply directly to the "release" branch, and then
+merge that into the "test" branch.
+
+To create diffstat and shortlog summaries of changes to include in a "please
+pull" request to Linus you can use:
+
+-------------------------------------------------
+$ git diff --stat origin..release
+-------------------------------------------------
+
+and
+
+-------------------------------------------------
+$ git log -p origin..release | git shortlog
+-------------------------------------------------
+
+Here are some of the scripts that simplify all this even further.
+
+-------------------------------------------------
+==== update script ====
+# Update a branch in my GIT tree. If the branch to be updated
+# is origin, then pull from kernel.org. Otherwise merge
+# origin/master branch into test|release branch
+
+case "$1" in
+test|release)
+ git checkout $1 && git pull . origin
+ ;;
+origin)
+ before=$(cat .git/refs/remotes/origin/master)
+ git fetch origin
+ after=$(cat .git/refs/remotes/origin/master)
+ if [ $before != $after ]
+ then
+ git log $before..$after | git shortlog
+ fi
+ ;;
+*)
+ echo "Usage: $0 origin|test|release" 1>&2
+ exit 1
+ ;;
+esac
+-------------------------------------------------
+
+-------------------------------------------------
+==== merge script ====
+# Merge a branch into either the test or release branch
+
+pname=$0
+
+usage()
+{
+ echo "Usage: $pname branch test|release" 1>&2
+ exit 1
+}
+
+if [ ! -f .git/refs/heads/"$1" ]
+then
+ echo "Can't see branch <$1>" 1>&2
+ usage
+fi
+
+case "$2" in
+test|release)
+ if [ $(git log $2..$1 | wc -c) -eq 0 ]
+ then
+ echo $1 already merged into $2 1>&2
+ exit 1
+ fi
+ git checkout $2 && git pull . $1
+ ;;
+*)
+ usage
+ ;;
+esac
+-------------------------------------------------
+
+-------------------------------------------------
+==== status script ====
+# report on status of my ia64 GIT tree
+
+gb=$(tput setab 2)
+rb=$(tput setab 1)
+restore=$(tput setab 9)
+
+if [ `git rev-list test..release | wc -c` -gt 0 ]
+then
+ echo $rb Warning: commits in release that are not in test $restore
+ git log test..release
+fi
+
+for branch in `ls .git/refs/heads`
+do
+ if [ $branch = test -o $branch = release ]
+ then
+ continue
+ fi
+
+ echo -n $gb ======= $branch ====== $restore " "
+ status=
+ for ref in test release origin/master
+ do
+ if [ `git rev-list $ref..$branch | wc -c` -gt 0 ]
+ then
+ status=$status${ref:0:1}
+ fi
+ done
+ case $status in
+ trl)
+ echo $rb Need to pull into test $restore
+ ;;
+ rl)
+ echo "In test"
+ ;;
+ l)
+ echo "Waiting for linus"
+ ;;
+ "")
+ echo $rb All done $restore
+ ;;
+ *)
+ echo $rb "<$status>" $restore
+ ;;
+ esac
+ git log origin/master..$branch | git shortlog
+done
+-------------------------------------------------
[[cleaning-up-history]]
allow people to get to important topics without necessarily reading
everything in between.
-Say something about .gitignore.
-
Scan Documentation/ for other stuff left out; in particular:
howto's
some of technical/?