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/>`_ or
86 install git with `Homebrew <http://brew.sh/>`_: ``brew install git``.
91 This simple code is often appears in documentation, but it is
92 important so let repeat it here. Git marks every commit with author
93 and committer names/emails, so configure your real name and preferred
96 $ git config --global user.name "User Name"
97 $ git config --global user.email user.name@example.org
103 Examples of git commands in this PEP use the following approach. It is
104 supposed that you, the user, works with a local repository named
105 ``python`` that has an upstream remote repo named ``origin``. Your
106 local repo has two branches ``v1`` and ``v2``. For most examples the
107 currently checked out branch is ``v2``. That is, it's assumed you have
108 done something like that::
110 $ git clone -b v2 http://git.python.org/python.git
112 $ git branch v1 origin/v1
114 The last command creates a new local branch v1 and sets
115 remotes/origin/v1 as its upstream remote branch.
117 The same result can achieved with commands::
119 $ git clone -b v1 http://git.python.org/python.git
121 $ git checkout --track origin/v2
123 The last command creates a new local branch v2, sets
124 remotes/origin/v2 as its upstream remote branch and checks it out into
125 the working directory.
128 Branches and branches
129 =====================
131 Git terminology can be a bit misleading. Take, for example, the term
132 "branch". In git it has two meanings. A branch is a directed line of
133 commits (possibly with merges). And a branch is a label or a pointer
134 assigned to a line of commits. It is important to differentiate when
135 you talk about commits and when about their labels. Lines of commits
136 are by itself unnamed and are usually only lengthening and merging.
137 Labels, on the other hand, can be created, moved, renamed and deleted
141 Remote repository and remote branches
142 =====================================
144 Another example of slightly misleading terminology. Remote
145 repositories are really remote, you access them via network (well, a
146 remote repository can be on your local disk, but it's still remote
147 because it's not the current repo).
149 Remote branches, on the other hand, are branches (pointers to commits)
150 in your local repository. They are there for you to remember what
151 branches and commits have been pulled from and pushed to what remote
152 repos (you can pull from and push to many remotes). Remote branches
153 live under ``remotes/REMOTE`` namespaces, e.g. ``remotes/origin/v2``.
155 To see the status of remote branches run::
159 To see local and remote branches (and tags) pointing to commits::
163 You never do your own development on remote branches. You create a
164 local branch that has a remote branch as upstream and do development
165 on that local branch. On push git updates remote branches, and on pull
166 git updates remote branches and fast-forwards, merges or rebases local
169 When you do an initial clone like this::
171 $ git clone -b v1 http://git.python.org/python.git
173 git clones remote repository ``http://git.python.org/python.git`` to
174 directory ``python``, creates remote branches and checks out branch
175 ``v1`` into the working directory.
177 Updating local and remote branches
178 ----------------------------------
180 There is a major difference between
184 $ git fetch REMOTE BRANCH
190 $ git fetch REMOTE BRANCH:BRANCH
192 The first command fetches commits from the named BRANCH in the REMOTE
193 repository that are not in your repository and leaves the id (the
194 hash) of the head commit in file .git/FETCH_HEAD. But it doesn't
195 update any branch (doesn't move any pointer).
197 The second command fetches commits from the named BRANCH in the REMOTE
198 repository that are not in your repository and updates both the local
199 branch BRANCH and its upstream remote branch. But it refuses to update
200 branches in case of non-fast-forward. And it refuses to update the
203 The first command is used internally by ``git pull``.
207 $ git pull REMOTE BRANCH
213 $ git fetch REMOTE BRANCH
214 $ git merge FETCH_HEAD # FETCH_HEAD is a literal here
216 Certainly, BRANCH in that case should be your current branch. If you
217 want to merge a different branch into your current branch first update
218 that non-current branch and then merge::
220 $ git fetch origin v1:v1 # Update v1
221 $ git pull --rebase origin v2 # Update the current branch v2 using
222 # rebase instead of merge
225 It is possible to configure git to make it fetch/pull a few branches
226 or all branches at once, so you can simply run
241 Pushing is a bit simpler. There is only one command ``push``. When you
246 $ git push origin v1 v2
248 git guesses (knowing upstream remote branches) that you really want
252 $ git push origin v1:v1 v2:v2
254 Git pushes commits to the remote repo and updates remote branches. Git
255 refuses to push commits that aren't fast-forwardable. You can
256 force-push anyway, but please remember - you can force-push to your
257 own repositories but don't force-push to public or shared repos. If
258 you find git refuses to push commits that aren't fast-forwardable,
259 better fetch and merge commits from the remote repo (or rebase your
260 commits on top of the fetched commits), then push. Only force-push if
261 you know what you do and why you do it. See the section `Commit
262 editing and caveats`_ below.
264 It is possible to configure git to make it push a few branches or all
265 branches at once, so you can simply run
277 Git refuses to push a branch if it's the current branch in the remote
278 non-bare repository: git refuses to update remote working directory.
279 You really should push only to bare repositories. For non-bare
280 repositories git prefers pull-based workflow.
285 Git automatically fetches tags that point to commits being fetched
286 during fetch/pull. To fetch all tags (and commits they point to) run
287 ``git fetch --tags origin``. To fetch some specific tags fetch them
290 $ git fetch origin tag NAME1 tag NAME2...
294 $ git fetch origin tag 1.4.2 tag 2.1.7
296 Git doesn't automatically pushes tags. That allows you to have private
297 tags (lightweight tags are also private for a repo, they cannot be
298 pushed). To push tag(s) list them explicitly::
300 $ git push origin tag 1.4.2
301 $ git push origin v1 v2 tag 2.1.7
304 Commit editing and caveats
305 ==========================
307 A warning not to edit published (pushed) commits also appears in
308 documentation but it's repeated here anyway as it's very important.
310 It is possible to recover from forced push but it's PITA for the
311 entire team. Please avoid it.
313 To see what commits have not been published yet compare the head of the
314 branch with its upstream remote branch::
316 $ git log origin/v2..
317 $ git log origin/v1..v1
319 For every branch that has an upstream remote branch git maintains an
320 alias @{upstream} (short version @{u}), so the commands above can be
326 To see the status of all branches::
330 To compare the status of local branches with a remote repo::
332 $ git remote show origin
334 Read `how to recover from upstream rebase
335 <https://git-scm.com/docs/git-rebase#_recovering_from_upstream_rebase>`_.
336 It is in ``git help rebase``.
338 On the other hand don't be too afraid about commit editing. You can
339 safely edit, remove, reorder, combine and split commits that hasn't
340 been pushed yet. You can even push commits to your own (backup) repo,
341 edit them later and force-push edited commits to replace what has
342 already been pushed. Not a problem until commits are in a public
343 or shared repository.
349 TODO: describe undo strategies: git reset, git revert, git checkout,
350 git reflog. "Commit early, commit often".
353 https://kernel.org/pub/software/scm/git/docs/howto/revert-a-faulty-merge.html
362 Staging area aka index is a distinguishing feature of git. See
364 <https://git.wiki.kernel.org/index.php/WhatIsTheIndex>`_ and
365 `IndexCommandQuickref
366 <https://git.wiki.kernel.org/index.php/IndexCommandQuickref>`_ in Git
377 Git has a builtin strategy for what Python core developers call
380 $ git merge -s ours v1 # null-merge v1 into v2
386 https://git-scm.com/book/en/Git-Tools-Rerere
389 Advanced configuration
390 ======================
395 Git has builtin mechanisms to handle line endings.
397 TODO: describe crlf configuration and .gitattributes.
403 TODO: dangling objects, git gc, git repack.
409 TODO: bash/zsh completion, bash/zsh prompt.
412 From Mercurial to git
413 =====================
415 Mercurial for Git users https://mercurial.selenic.com/wiki/GitConcepts
417 https://github.com/felipec/git-remote-hg
419 https://hg-git.github.io/
431 This document has been placed in the public domain.
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