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``.
88 `Atlassins's SourceTree <https://www.sourcetreeapp.com/>`_ is a free
89 Git and Mercurial GUI client for Windows or Mac.
94 This simple code is often appears in documentation, but it is
95 important so let repeat it here. Git marks every commit with author
96 and committer names/emails, so configure your real name and preferred
99 $ git config --global user.name "User Name"
100 $ git config --global user.email user.name@example.org
106 Examples of git commands in this PEP use the following approach. It is
107 supposed that you, the user, works with a local repository named
108 ``python`` that has an upstream remote repo named ``origin``. Your
109 local repo has two branches ``v1`` and ``v2``. For most examples the
110 currently checked out branch is ``v2``. That is, it's assumed you have
111 done something like that::
113 $ git clone -b v2 http://git.python.org/python.git
115 $ git branch v1 origin/v1
117 The last command creates a new local branch v1 and sets
118 remotes/origin/v1 as its upstream remote branch.
120 The same result can achieved with commands::
122 $ git clone -b v1 http://git.python.org/python.git
124 $ git checkout --track origin/v2
126 The last command creates a new local branch v2, sets
127 remotes/origin/v2 as its upstream remote branch and checks it out into
128 the working directory.
131 Branches and branches
132 =====================
134 Git terminology can be a bit misleading. Take, for example, the term
135 "branch". In git it has two meanings. A branch is a directed line of
136 commits (possibly with merges). And a branch is a label or a pointer
137 assigned to a line of commits. It is important to differentiate when
138 you talk about commits and when about their labels. Lines of commits
139 are by itself unnamed and are usually only lengthening and merging.
140 Labels, on the other hand, can be created, moved, renamed and deleted
144 Remote repository and remote branches
145 =====================================
147 Another example of slightly misleading terminology. Remote
148 repositories are really remote, you access them via network (well, a
149 remote repository can be on your local disk, but it's still remote
150 because it's not the current repo).
152 Remote branches, on the other hand, are branches (pointers to commits)
153 in your local repository. They are there for you to remember what
154 branches and commits have been pulled from and pushed to what remote
155 repos (you can pull from and push to many remotes). Remote branches
156 live under ``remotes/REMOTE`` namespaces, e.g. ``remotes/origin/v2``.
158 To see the status of remote branches run::
162 To see local and remote branches (and tags) pointing to commits::
166 You never do your own development on remote branches. You create a
167 local branch that has a remote branch as upstream and do development
168 on that local branch. On push git updates remote branches, and on pull
169 git updates remote branches and fast-forwards, merges or rebases local
172 When you do an initial clone like this::
174 $ git clone -b v1 http://git.python.org/python.git
176 git clones remote repository ``http://git.python.org/python.git`` to
177 directory ``python``, creates remote branches and checks out branch
178 ``v1`` into the working directory.
180 Updating local and remote branches
181 ----------------------------------
183 There is a major difference between
187 $ git fetch REMOTE BRANCH
193 $ git fetch REMOTE BRANCH:BRANCH
195 The first command fetches commits from the named BRANCH in the REMOTE
196 repository that are not in your repository and leaves the id (the
197 hash) of the head commit in file .git/FETCH_HEAD. But it doesn't
198 update any branch (doesn't move any pointer).
200 The second command fetches commits from the named BRANCH in the REMOTE
201 repository that are not in your repository and updates both the local
202 branch BRANCH and its upstream remote branch. But it refuses to update
203 branches in case of non-fast-forward. And it refuses to update the
206 The first command is used internally by ``git pull``.
210 $ git pull REMOTE BRANCH
216 $ git fetch REMOTE BRANCH
217 $ git merge FETCH_HEAD # FETCH_HEAD is a literal here
219 Certainly, BRANCH in that case should be your current branch. If you
220 want to merge a different branch into your current branch first update
221 that non-current branch and then merge::
223 $ git fetch origin v1:v1 # Update v1
224 $ git pull --rebase origin v2 # Update the current branch v2 using
225 # rebase instead of merge
228 It is possible to configure git to make it fetch/pull a few branches
229 or all branches at once, so you can simply run
244 Pushing is a bit simpler. There is only one command ``push``. When you
249 $ git push origin v1 v2
251 git guesses (knowing upstream remote branches) that you really want
255 $ git push origin v1:v1 v2:v2
257 Git pushes commits to the remote repo and updates remote branches. Git
258 refuses to push commits that aren't fast-forwardable. You can
259 force-push anyway, but please remember - you can force-push to your
260 own repositories but don't force-push to public or shared repos. If
261 you find git refuses to push commits that aren't fast-forwardable,
262 better fetch and merge commits from the remote repo (or rebase your
263 commits on top of the fetched commits), then push. Only force-push if
264 you know what you do and why you do it. See the section `Commit
265 editing and caveats`_ below.
267 It is possible to configure git to make it push a few branches or all
268 branches at once, so you can simply run
280 Git refuses to push a branch if it's the current branch in the remote
281 non-bare repository: git refuses to update remote working directory.
282 You really should push only to bare repositories. For non-bare
283 repositories git prefers pull-based workflow.
288 Git automatically fetches tags that point to commits being fetched
289 during fetch/pull. To fetch all tags (and commits they point to) run
290 ``git fetch --tags origin``. To fetch some specific tags fetch them
293 $ git fetch origin tag NAME1 tag NAME2...
297 $ git fetch origin tag 1.4.2 tag 2.1.7
299 Git doesn't automatically pushes tags. That allows you to have private
300 tags (lightweight tags are also private for a repo, they cannot be
301 pushed). To push tags list them explicitly::
303 $ git push origin tag 1.4.2
304 $ git push origin v1 v2 tag 2.1.7
307 Commit editing and caveats
308 ==========================
310 A warning not to edit published (pushed) commits also appears in
311 documentation but it's repeated here anyway as it's very important.
313 It is possible to recover from forced push but it's PITA for the
314 entire team. Please avoid it.
316 To see what commits have not been published yet compare the head of the
317 branch with its upstream remote branch::
319 $ git log origin/v2..
320 $ git log origin/v1..v1
322 For every branch that has an upstream remote branch git maintains an
323 alias @{upstream} (short version @{u}), so the commands above can be
329 To see the status of all branches::
333 To compare the status of local branches with a remote repo::
335 $ git remote show origin
337 Read `how to recover from upstream rebase
338 <https://git-scm.com/docs/git-rebase#_recovering_from_upstream_rebase>`_.
339 It is in ``git help rebase``.
341 On the other hand don't be too afraid about commit editing. You can
342 safely edit, remove, reorder, combine and split commits that hasn't
343 been pushed yet. You can even push commits to your own (backup) repo,
344 edit them later and force-push edited commits to replace what has
345 already been pushed. Not a problem until commits are in a public
346 or shared repository.
352 TODO: describe undo strategies: git reset, git revert, git checkout,
353 git reflog. "Commit early, commit often".
356 https://kernel.org/pub/software/scm/git/docs/howto/revert-a-faulty-merge.html
365 Staging area aka index is a distinguishing feature of git. See
367 <https://git.wiki.kernel.org/index.php/WhatIsTheIndex>`_ and
368 `IndexCommandQuickref
369 <https://git.wiki.kernel.org/index.php/IndexCommandQuickref>`_ in Git
380 Git has a builtin strategy for what Python core developers call
383 $ git merge -s ours v1 # null-merge v1 into v2
389 https://git-scm.com/book/en/Git-Tools-Rerere
392 Advanced configuration
393 ======================
398 Git has builtin mechanisms to handle line endings.
400 TODO: describe crlf configuration and .gitattributes.
406 TODO: dangling objects, git gc, git repack.
412 TODO: bash/zsh completion, bash/zsh prompt.
415 From Mercurial to git
416 =====================
418 Mercurial for Git users https://mercurial.selenic.com/wiki/GitConcepts
420 https://github.com/felipec/git-remote-hg
422 https://hg-git.github.io/
434 This document has been placed in the public domain.
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