refs: handle zero oid for pseudorefs

[git.git] / Documentation / giteveryday.txt

giteveryday(7)
==============

NAME
----
giteveryday - A useful minimum set of commands for Everyday Git

SYNOPSIS
--------

Everyday Git With 20 Commands Or So

DESCRIPTION
-----------

Git users can broadly be grouped into four categories for the purposes of
describing here a small set of useful command for everyday Git.

*       <<STANDALONE,Individual Developer (Standalone)>> commands are essential
        for anybody who makes a commit, even for somebody who works alone.

*       If you work with other people, you will need commands listed in
        the <<PARTICIPANT,Individual Developer (Participant)>> section as well.

*       People who play the <<INTEGRATOR,Integrator>> role need to learn some
        more commands in addition to the above.

*       <<ADMINISTRATION,Repository Administration>> commands are for system
        administrators who are responsible for the care and feeding
        of Git repositories.


Individual Developer (Standalone)[[STANDALONE]]
-----------------------------------------------

A standalone individual developer does not exchange patches with
other people, and works alone in a single repository, using the
following commands.

  * linkgit:git-init[1] to create a new repository.

  * linkgit:git-log[1] to see what happened.

  * linkgit:git-checkout[1] and linkgit:git-branch[1] to switch
    branches.

  * linkgit:git-add[1] to manage the index file.

  * linkgit:git-diff[1] and linkgit:git-status[1] to see what
    you are in the middle of doing.

  * linkgit:git-commit[1] to advance the current branch.

  * linkgit:git-reset[1] and linkgit:git-checkout[1] (with
    pathname parameters) to undo changes.

  * linkgit:git-merge[1] to merge between local branches.

  * linkgit:git-rebase[1] to maintain topic branches.

  * linkgit:git-tag[1] to mark a known point.

Examples
~~~~~~~~

Use a tarball as a starting point for a new repository.::
+
------------
$ tar zxf frotz.tar.gz
$ cd frotz
$ git init
$ git add . <1>
$ git commit -m "import of frotz source tree."
$ git tag v2.43 <2>
------------
+
<1> add everything under the current directory.
<2> make a lightweight, unannotated tag.

Create a topic branch and develop.::
+
------------
$ git checkout -b alsa-audio <1>
$ edit/compile/test
$ git checkout -- curses/ux_audio_oss.c <2>
$ git add curses/ux_audio_alsa.c <3>
$ edit/compile/test
$ git diff HEAD <4>
$ git commit -a -s <5>
$ edit/compile/test
$ git diff HEAD^ <6>
$ git commit -a --amend <7>
$ git checkout master <8>
$ git merge alsa-audio <9>
$ git log --since='3 days ago' <10>
$ git log v2.43.. curses/ <11>
------------
+
<1> create a new topic branch.
<2> revert your botched changes in `curses/ux_audio_oss.c`.
<3> you need to tell Git if you added a new file; removal and
modification will be caught if you do `git commit -a` later.
<4> to see what changes you are committing.
<5> commit everything, as you have tested, with your sign-off.
<6> look at all your changes including the previous commit.
<7> amend the previous commit, adding all your new changes,
using your original message.
<8> switch to the master branch.
<9> merge a topic branch into your master branch.
<10> review commit logs; other forms to limit output can be
combined and include `-10` (to show up to 10 commits),
`--until=2005-12-10`, etc.
<11> view only the changes that touch what's in `curses/`
directory, since `v2.43` tag.


Individual Developer (Participant)[[PARTICIPANT]]
-------------------------------------------------

A developer working as a participant in a group project needs to
learn how to communicate with others, and uses these commands in
addition to the ones needed by a standalone developer.

  * linkgit:git-clone[1] from the upstream to prime your local
    repository.

  * linkgit:git-pull[1] and linkgit:git-fetch[1] from "origin"
    to keep up-to-date with the upstream.

  * linkgit:git-push[1] to shared repository, if you adopt CVS
    style shared repository workflow.

  * linkgit:git-format-patch[1] to prepare e-mail submission, if
    you adopt Linux kernel-style public forum workflow.

  * linkgit:git-send-email[1] to send your e-mail submission without
    corruption by your MUA.

  * linkgit:git-request-pull[1] to create a summary of changes
    for your upstream to pull.


Examples
~~~~~~~~

Clone the upstream and work on it.  Feed changes to upstream.::
+
------------
$ git clone git://git.kernel.org/pub/scm/.../torvalds/linux-2.6 my2.6
$ cd my2.6
$ git checkout -b mine master <1>
$ edit/compile/test; git commit -a -s <2>
$ git format-patch master <3>
$ git send-email --to="person <email@example.com>" 00*.patch <4>
$ git checkout master <5>
$ git pull <6>
$ git log -p ORIG_HEAD.. arch/i386 include/asm-i386 <7>
$ git ls-remote --heads http://git.kernel.org/.../jgarzik/libata-dev.git <8>
$ git pull git://git.kernel.org/pub/.../jgarzik/libata-dev.git ALL <9>
$ git reset --hard ORIG_HEAD <10>
$ git gc <11>
------------
+
<1> checkout a new branch `mine` from master.
<2> repeat as needed.
<3> extract patches from your branch, relative to master,
<4> and email them.
<5> return to `master`, ready to see what's new
<6> `git pull` fetches from `origin` by default and merges into the
current branch.
<7> immediately after pulling, look at the changes done upstream
since last time we checked, only in the
area we are interested in.
<8> check the branch names in an external repository (if not known).
<9> fetch from a specific branch `ALL` from a specific repository
and merge it.
<10> revert the pull.
<11> garbage collect leftover objects from reverted pull.


Push into another repository.::
+
------------
satellite$ git clone mothership:frotz frotz <1>
satellite$ cd frotz
satellite$ git config --get-regexp '^(remote|branch)\.' <2>
remote.origin.url mothership:frotz
remote.origin.fetch refs/heads/*:refs/remotes/origin/*
branch.master.remote origin
branch.master.merge refs/heads/master
satellite$ git config remote.origin.push \
           +refs/heads/*:refs/remotes/satellite/* <3>
satellite$ edit/compile/test/commit
satellite$ git push origin <4>

mothership$ cd frotz
mothership$ git checkout master
mothership$ git merge satellite/master <5>
------------
+
<1> mothership machine has a frotz repository under your home
directory; clone from it to start a repository on the satellite
machine.
<2> clone sets these configuration variables by default.
It arranges `git pull` to fetch and store the branches of mothership
machine to local `remotes/origin/*` remote-tracking branches.
<3> arrange `git push` to push all local branches to
their corresponding branch of the mothership machine.
<4> push will stash all our work away on `remotes/satellite/*`
remote-tracking branches on the mothership machine.  You could use this
as a back-up method. Likewise, you can pretend that mothership
"fetched" from you (useful when access is one sided).
<5> on mothership machine, merge the work done on the satellite
machine into the master branch.

Branch off of a specific tag.::
+
------------
$ git checkout -b private2.6.14 v2.6.14 <1>
$ edit/compile/test; git commit -a
$ git checkout master
$ git cherry-pick v2.6.14..private2.6.14 <2>
------------
+
<1> create a private branch based on a well known (but somewhat behind)
tag.
<2> forward port all changes in `private2.6.14` branch to `master` branch
without a formal "merging". Or longhand +
`git format-patch -k -m --stdout v2.6.14..private2.6.14 |
  git am -3 -k`

An alternate participant submission mechanism is using the
`git request-pull` or pull-request mechanisms (e.g as used on
GitHub (www.github.com) to notify your upstream of your
contribution.

Integrator[[INTEGRATOR]]
------------------------

A fairly central person acting as the integrator in a group
project receives changes made by others, reviews and integrates
them and publishes the result for others to use, using these
commands in addition to the ones needed by participants.

This section can also be used by those who respond to `git
request-pull` or pull-request on GitHub (www.github.com) to
integrate the work of others into their history. An sub-area
lieutenant for a repository will act both as a participant and
as an integrator.


  * linkgit:git-am[1] to apply patches e-mailed in from your
    contributors.

  * linkgit:git-pull[1] to merge from your trusted lieutenants.

  * linkgit:git-format-patch[1] to prepare and send suggested
    alternative to contributors.

  * linkgit:git-revert[1] to undo botched commits.

  * linkgit:git-push[1] to publish the bleeding edge.


Examples
~~~~~~~~

A typical integrator's Git day.::
+
------------
$ git status <1>
$ git branch --no-merged master <2>
$ mailx <3>
& s 2 3 4 5 ./+to-apply
& s 7 8 ./+hold-linus
& q
$ git checkout -b topic/one master
$ git am -3 -i -s ./+to-apply <4>
$ compile/test
$ git checkout -b hold/linus && git am -3 -i -s ./+hold-linus <5>
$ git checkout topic/one && git rebase master <6>
$ git checkout pu && git reset --hard next <7>
$ git merge topic/one topic/two && git merge hold/linus <8>
$ git checkout maint
$ git cherry-pick master~4 <9>
$ compile/test
$ git tag -s -m "GIT 0.99.9x" v0.99.9x <10>
$ git fetch ko && for branch in master maint next pu <11>
    do
        git show-branch ko/$branch $branch <12>
    done
$ git push --follow-tags ko <13>
------------
+
<1> see what you were in the middle of doing, if anything.
<2> see which branches haven't been merged into `master` yet.
Likewise for any other integration branches e.g. `maint`, `next`
and `pu` (potential updates).
<3> read mails, save ones that are applicable, and save others
that are not quite ready (other mail readers are available).
<4> apply them, interactively, with your sign-offs.
<5> create topic branch as needed and apply, again with sign-offs.
<6> rebase internal topic branch that has not been merged to the
master or exposed as a part of a stable branch.
<7> restart `pu` every time from the next.
<8> and bundle topic branches still cooking.
<9> backport a critical fix.
<10> create a signed tag.
<11> make sure master was not accidentally rewound beyond that
already pushed out.
<12> In the output from `git show-branch`, `master` should have
everything `ko/master` has, and `next` should have
everything `ko/next` has, etc.
<13> push out the bleeding edge, together with new tags that point
into the pushed history.

In this example, the `ko` shorthand points at the Git maintainer's
repository at kernel.org, and looks like this:

------------
(in .git/config)
[remote "ko"]
        url = kernel.org:/pub/scm/git/git.git
        fetch = refs/heads/*:refs/remotes/ko/*
        push = refs/heads/master
        push = refs/heads/next
        push = +refs/heads/pu
        push = refs/heads/maint
------------


Repository Administration[[ADMINISTRATION]]
-------------------------------------------

A repository administrator uses the following tools to set up
and maintain access to the repository by developers.

  * linkgit:git-daemon[1] to allow anonymous download from
    repository.

  * linkgit:git-shell[1] can be used as a 'restricted login shell'
    for shared central repository users.

  * linkgit:git-http-backend[1] provides a server side implementation
    of Git-over-HTTP ("Smart http") allowing both fetch and push services.

  * linkgit:gitweb[1] provides a web front-end to Git repositories,
    which can be set-up using the linkgit:git-instaweb[1] script.

link:howto/update-hook-example.html[update hook howto] has a good
example of managing a shared central repository.

In addition there are a number of other widely deployed hosting, browsing
and reviewing solutions such as:

  * gitolite, gerrit code review, cgit and others.

Examples
~~~~~~~~
We assume the following in /etc/services::
+
------------
$ grep 9418 /etc/services
git             9418/tcp                # Git Version Control System
------------

Run git-daemon to serve /pub/scm from inetd.::
+
------------
$ grep git /etc/inetd.conf
git     stream  tcp     nowait  nobody \
  /usr/bin/git-daemon git-daemon --inetd --export-all /pub/scm
------------
+
The actual configuration line should be on one line.

Run git-daemon to serve /pub/scm from xinetd.::
+
------------
$ cat /etc/xinetd.d/git-daemon
# default: off
# description: The Git server offers access to Git repositories
service git
{
        disable = no
        type            = UNLISTED
        port            = 9418
        socket_type     = stream
        wait            = no
        user            = nobody
        server          = /usr/bin/git-daemon
        server_args     = --inetd --export-all --base-path=/pub/scm
        log_on_failure  += USERID
}
------------
+
Check your xinetd(8) documentation and setup, this is from a Fedora system.
Others might be different.

Give push/pull only access to developers using git-over-ssh.::

e.g. those using:
`$ git push/pull ssh://host.xz/pub/scm/project`
+
------------
$ grep git /etc/passwd <1>
alice:x:1000:1000::/home/alice:/usr/bin/git-shell
bob:x:1001:1001::/home/bob:/usr/bin/git-shell
cindy:x:1002:1002::/home/cindy:/usr/bin/git-shell
david:x:1003:1003::/home/david:/usr/bin/git-shell
$ grep git /etc/shells <2>
/usr/bin/git-shell
------------
+
<1> log-in shell is set to /usr/bin/git-shell, which does not
allow anything but `git push` and `git pull`.  The users require
ssh access to the machine.
<2> in many distributions /etc/shells needs to list what is used
as the login shell.

CVS-style shared repository.::
+
------------
$ grep git /etc/group <1>
git:x:9418:alice,bob,cindy,david
$ cd /home/devo.git
$ ls -l <2>
  lrwxrwxrwx   1 david git    17 Dec  4 22:40 HEAD -> refs/heads/master
  drwxrwsr-x   2 david git  4096 Dec  4 22:40 branches
  -rw-rw-r--   1 david git    84 Dec  4 22:40 config
  -rw-rw-r--   1 david git    58 Dec  4 22:40 description
  drwxrwsr-x   2 david git  4096 Dec  4 22:40 hooks
  -rw-rw-r--   1 david git 37504 Dec  4 22:40 index
  drwxrwsr-x   2 david git  4096 Dec  4 22:40 info
  drwxrwsr-x   4 david git  4096 Dec  4 22:40 objects
  drwxrwsr-x   4 david git  4096 Nov  7 14:58 refs
  drwxrwsr-x   2 david git  4096 Dec  4 22:40 remotes
$ ls -l hooks/update <3>
  -r-xr-xr-x   1 david git  3536 Dec  4 22:40 update
$ cat info/allowed-users <4>
refs/heads/master       alice\|cindy
refs/heads/doc-update   bob
refs/tags/v[0-9]*       david
------------
+
<1> place the developers into the same git group.
<2> and make the shared repository writable by the group.
<3> use update-hook example by Carl from Documentation/howto/
for branch policy control.
<4> alice and cindy can push into master, only bob can push into doc-update.
david is the release manager and is the only person who can
create and push version tags.

GIT
---
Part of the linkgit:git[1] suite