2 Title: Collecting information about git
5 Author: Oleg Broytman <phd@phdru.name>
8 Content-Type: text/x-rst
15 This Informational PEP collects information about git. There is, of
16 course, a lot of documentation for git, so the PEP concentrates on
17 more complex issues, scenarios and topics.
19 The plan is to extend the PEP in the future collecting information
20 about equivalence of Mercurial and git scenarios to help migrating
21 Python development from Mercurial to git.
23 The author of the PEP doesn't currently plan to write a Process PEP on
24 migration from Mercurial to git.
30 Git is accompanied with a lot of documentation, both online and
33 Documentation for starters
34 --------------------------
37 <https://www.kernel.org/pub/software/scm/git/docs/gittutorial.html>`_,
39 <https://www.kernel.org/pub/software/scm/git/docs/gittutorial-2.html>`_.
42 <https://www.kernel.org/pub/software/scm/git/docs/user-manual.html>`_.
43 `Everyday GIT With 20 Commands Or So
44 <https://www.kernel.org/pub/software/scm/git/docs/everyday.html>`_.
46 <https://www.kernel.org/pub/software/scm/git/docs/gitworkflows.html>`_.
49 <http://www-cs-students.stanford.edu/~blynn/gitmagic/index.html>`_,
50 also with a number of translations.
52 Advanced documentation
53 ----------------------
55 `Pro Git <https://git-scm.com/book>`_. The Book about git. Buy it at
56 Amazon or download in PDF, mobi, or ePub form. Has translations to
57 many different languages. Download Russian translation from `GArik
58 <https://github.com/GArik/progit/wiki>`_.
60 `Git Wiki <https://git.wiki.kernel.org/index.php/Main_Page>`_.
65 Git has builtin help: run ``git help TOPIC``. For example, run
66 ``git help git`` or ``git help help``.
72 Download and installation
73 -------------------------
75 Unix users: download and install using your package manager.
77 Microsoft Windows: download `git-for-windows
78 <https://github.com/git-for-windows/git/releases>`_ or `msysGit
79 <https://github.com/msysgit/msysgit/releases>`_.
81 MacOS X: use git installed with `XCode
82 <https://developer.apple.com/xcode/downloads/>`_ or download from
83 `MacPorts <https://www.macports.org/ports.php?by=name&substr=git>`_ or
85 <http://sourceforge.net/projects/git-osx-installer/files/>`_.
90 This simple code is often appears in documentation, but it is
91 important so let repeat it here. Git marks every commit with author
92 and committer names/emails, so configure your real name and preferred
95 $ git config --global user.name "User Name"
96 $ git config --global user.email user.name@example.org
102 Examples of git commands in this PEP use the following approach. It is
103 supposed that you, the user, works with a local repository named
104 ``python`` that has an upstream remote repo named ``origin``. Your
105 local repo has two branches ``v1`` and ``v2``. For most examples the
106 currently checked out branch is ``v2``. That is, it's assumed you have
107 done something like that::
109 $ git clone -b v2 http://git.python.org/python.git
111 $ git branch v1 origin/v1
113 The last command creates a new local branch v1 and sets
114 remotes/origin/v1 as its upstream remote branch.
116 The same result can achieved with commands::
118 $ git clone -b v1 http://git.python.org/python.git
120 $ git checkout --track origin/v2
122 The last command creates a new local branch v2, sets
123 remotes/origin/v2 as its upstream remote branch and checks it out into
124 the working directory.
127 Branches and branches
128 =====================
130 Git terminology can be a bit misleading. Take, for example, the term
131 "branch". In git it has two meanings. A branch is a directed line of
132 commits (possibly with merges). And a branch is a label or a pointer
133 assigned to a line of commits. It is important to differentiate when
134 you talk about commits and when about their labels. Lines of commits
135 are by itself unnamed and are usually only lengthening and merging.
136 Labels, on the other hand, can be created, moved, renamed and deleted
140 Remote repository and remote branches
141 =====================================
143 Another example of slightly misleading terminology. Remote
144 repositories are really remote, you access them via network (well, a
145 remote repository can be on your local disk, but it's still remote
146 because it's not the current repo).
148 Remote branches, on the other hand, are branches (pointers to commits)
149 in your local repository. They are there for you to remember what
150 branches and commits have been pulled from and pushed to what remote
151 repos (you can pull from and push to many remotes). Remote branches
152 live under ``remotes/REMOTE`` namespaces, e.g. ``remotes/origin/v2``.
154 To see the status of remote branches run::
158 To see local and remote branches (and tags) pointing to commits::
162 You never do your own development on remote branches. You create a
163 local branch that has a remote branch as upstream and do development
164 on that local branch. On push git updates remote branches, and on pull
165 git updates remote branches and fast-forwards, merges or rebases local
168 When you do an initial clone like this::
170 $ git clone -b v1 http://git.python.org/python.git
172 git clones remote repository ``http://git.python.org/python.git`` to
173 directory ``python``, creates remote branches and checks out branch
174 ``v1`` into the working directory.
176 Updating local and remote branches
177 ----------------------------------
179 There is a major difference between
183 $ git fetch REMOTE BRANCH
189 $ git fetch REMOTE BRANCH:BRANCH
191 The first command fetches commits from the named BRANCH in the REMOTE
192 repository that are not in your repository and leaves the id (the
193 hash) of the head commit in file .git/FETCH_HEAD. But it doesn't
194 update any branch (doesn't move any pointer).
196 The second command fetches commits from the named BRANCH in the REMOTE
197 repository that are not in your repository and updates both the local
198 branch BRANCH and its upstream remote branch. But it refuses to update
199 branches in case of non-fast-forward. And it refuses to update the
202 The first command is used internally by ``git pull``.
206 $ git pull REMOTE BRANCH
212 $ git fetch REMOTE BRANCH
213 $ git merge FETCH_HEAD # FETCH_HEAD is a literal here
215 Certainly, BRANCH in that case should be your current branch. If you
216 want to merge a different branch into your current branch first update
217 that non-current branch and then merge::
219 $ git fetch origin v1:v1 # Update v1
220 $ git pull --rebase origin v2 # Update the current branch v2 using
221 # rebase instead of merge
224 It is possible to configure git to make it fetch/pull a few branches
225 or all branches at once, so you can simply run
240 Pushing is a bit simpler. There is only one command ``push``. When you
245 $ git push origin v1 v2
247 git guesses (knowing upstream remote branches) that you really want
251 $ git push origin v1:v1 v2:v2
253 Git pushes commits to the remote repo and updates remote branches. Git
254 refuses to push commits that aren't fast-forwardable. You can
255 force-push anyway, but please remember - you can force-push to your
256 own repositories but don't force-push to public or shared repos. If
257 you find git refuses to push commits that aren't fast-forwardable,
258 better fetch and merge commits from the remote repo (or rebase your
259 commits on top of the fetched commits), then push. Only force-push if
260 you know what you do and why you do it. See the section `Commit
261 editing and caveats`_ below.
263 It is possible to configure git to make it push a few branches or all
264 branches at once, so you can simply run
276 Git refuses to push a branch if it's the current branch in the remote
277 non-bare repository: git refuses to update remote working directory.
278 You really should push only to bare repositories. For non-bare
279 repositories git prefers pull-based workflow.
284 Git automatically fetches tags that point to commits being fetched
285 during fetch/pull. To fetch all tags (and commits they point to) run
286 ``git fetch --tags origin``. To fetch some specific tags fetch them
289 $ git fetch origin tag NAME1 tag NAME2...
293 $ git fetch origin tag 1.4.2 tag 2.1.7
295 Git doesn't automatically pushes tags. That allows you to have private
296 tags (lightweight tags are also private for a repo, they cannot be
297 pushed). To push tag(s) list them explicitly::
299 $ git push origin tag 1.4.2
300 $ git push origin v1 v2 tag 2.1.7
303 Commit editing and caveats
304 ==========================
306 A warning not to edit published (pushed) commits also appears in
307 documentation but it's repeated here anyway as it's very important.
309 It is possible to recover from forced push but it's PITA for the
310 entire team. Please avoid it.
312 To see what commits have not been published yet compare the head of the
313 branch with its upstream remote branch::
315 $ git log origin/v2..
316 $ git log origin/v1..v1
318 For every branch that has an upstream remote branch git maintains an
319 alias @{upstream} (short version @{u}), so the commands above can be
325 To see the status of all branches::
329 To compare the status of local branches with a remote repo::
331 $ git remote show origin
333 Read `how to recover from upstream rebase
334 <https://git-scm.com/docs/git-rebase#_recovering_from_upstream_rebase>`_.
335 It is in ``git help rebase``.
337 On the other hand don't be too afraid about commit editing. You can
338 safely edit, remove, reorder, combine and split commits that hasn't
339 been pushed yet. You can even push commits to your own (backup) repo,
340 edit them later and force-push edited commits to replace what has
341 already been pushed. Not a problem until commits are in a public
342 or shared repository.
348 TODO: describe undo strategies: git reset, git revert, git checkout,
349 git reflog. "Commit early, commit often".
352 https://kernel.org/pub/software/scm/git/docs/howto/revert-a-faulty-merge.html
361 Staging area aka index is a distinguishing feature of git. See
363 <https://git.wiki.kernel.org/index.php/WhatIsTheIndex>`_ and
364 `IndexCommandQuickref
365 <https://git.wiki.kernel.org/index.php/IndexCommandQuickref>`_ in Git
376 Git has a builtin strategy for what Python core developers call
379 $ git merge -s ours v1 # null-merge v1 into v2
385 https://git-scm.com/book/en/Git-Tools-Rerere
388 Advanced configuration
389 ======================
394 Git has builtin mechanisms to handle line endings.
396 TODO: describe crlf configuration and .gitattributes.
402 TODO: dangling objects, git gc, git repack.
408 TODO: bash/zsh completion, bash/zsh prompt.
411 From Mercurial to git
412 =====================
414 Mercurial for Git users https://mercurial.selenic.com/wiki/GitConcepts
416 https://github.com/felipec/git-remote-hg
418 https://hg-git.github.io/
430 This document has been placed in the public domain.
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