Version: $Revision$
Last-Modified: $Date$
Author: Oleg Broytman <phd@phdru.name>
-Status: Active
+Status: Draft
Type: Informational
Content-Type: text/x-rst
Created: 01-Jun-2015
`Git workflows
<https://www.kernel.org/pub/software/scm/git/docs/gitworkflows.html>`_.
+Advanced documentation
+----------------------
+
`Git Magic
<http://www-cs-students.stanford.edu/~blynn/gitmagic/index.html>`_,
also with a number of translations.
-Advanced documentation
-----------------------
-
`Pro Git <https://git-scm.com/book>`_. The Book about git. Buy it at
Amazon or download in PDF, mobi, or ePub form. Has translations to
many different languages. Download Russian translation from `GArik
Unix users: download and install using your package manager.
Microsoft Windows: download `git-for-windows
-<https://git-for-windows.github.io/>`_.
+<https://github.com/git-for-windows/git/releases>`_ or `msysGit
+<https://github.com/msysgit/msysgit/releases>`_.
MacOS X: use git installed with `XCode
-<https://developer.apple.com/xcode/downloads/>`_ or download
+<https://developer.apple.com/xcode/downloads/>`_ or download from
+`MacPorts <https://www.macports.org/ports.php?by=name&substr=git>`_ or
`git-osx-installer
-<http://sourceforge.net/projects/git-osx-installer/files/>`_.
+<http://sourceforge.net/projects/git-osx-installer/files/>`_ or
+install git with `Homebrew <http://brew.sh/>`_: ``brew install git``.
+
+`git-cola <https://git-cola.github.io/index.html>`_ is a sleek and
+powerful Git GUI written in Python and GPL licensed. Linux, Windows,
+MacOS X.
+
+`TortoiseGit <https://tortoisegit.org/>`_ is a Windows Shell Interface
+to Git based on TortoiseSVN; open source.
Initial configuration
---------------------
This simple code is often appears in documentation, but it is
-important so let repeat it here. Git marks every commit with author
-and commiter names/emails, so configure your real name and preferred
-email::
+important so let repeat it here. Git stores author and committer
+names/emails in every commit, so configure your real name and
+preferred email::
$ git config --global user.name "User Name"
$ git config --global user.email user.name@example.org
supposed that you, the user, works with a local repository named
``python`` that has an upstream remote repo named ``origin``. Your
local repo has two branches ``v1`` and ``v2``. For most examples the
-currently checked out branch is ``v2``. That is, it's assumed you did
-something like that::
+currently checked out branch is ``v2``. That is, it's assumed you have
+done something like that::
+
+ $ git clone -b v2 http://git.python.org/python.git
+ $ cd python
+ $ git branch v1 origin/v1
+
+The first command clones remote repository into local directory
+`python``, creates a new local branch v2, sets remotes/origin/v2 as
+its upstream remote branch and checks it out into the working
+directory.
+
+The last command creates a new local branch v1 and sets
+remotes/origin/v1 as its upstream remote branch.
+
+The same result can be achieved with commands::
$ git clone -b v1 http://git.python.org/python.git
$ cd python
- $ git fetch origin v2:v2
- $ git checkout -b v2
+ $ git checkout --track origin/v2
+
+The last command creates a new local branch v2, sets
+remotes/origin/v2 as its upstream remote branch and checks it out into
+the working directory.
Branches and branches
$ git log --decorate
You never do your own development on remote branches. You create a
-local branch that has a remote branch as an upstream and do
-development on that local branch. On push git updates remote branches,
-and on pull git updates remote branches and fast-forwards, merges or
-rebases local branches.
+local branch that has a remote branch as upstream and do development
+on that local branch. On push git updates remote branches, and on pull
+git updates remote branches and fast-forwards, merges or rebases local
+branches.
When you do an initial clone like this::
$ git clone -b v1 http://git.python.org/python.git
git clones remote repository ``http://git.python.org/python.git`` to
-directory ``python``, creates remote branches and checks out branch
-``v1`` into the working directory.
+directory ``python``, creates remote branches, creates a local branch
+``v1``, configure it to track upstream remotes/origin/v1 branch and
+checks out ``v1`` into the working directory.
Updating local and remote branches
----------------------------------
The first command fetches commits from the named BRANCH in the REMOTE
repository that are not in your repository and leaves the id (the
hash) of the head commit in file .git/FETCH_HEAD. But it doesn't
-update any branch (doesn't move any label).
+update any branch (doesn't move any pointer).
The second command fetches commits from the named BRANCH in the REMOTE
repository that are not in your repository and updates both the local
branches in case of non-fast-forward. And it refuses to update the
current branch.
-The first command is used internall by ``git pull``.
+The first command is used internally by ``git pull``.
::
::
$ git fetch REMOTE BRANCH
- $ git merge FETCH_HEAD # FETCH_HEAD is a literal here
+ $ git merge FETCH_HEAD # FETCH_HEAD is a literal here
Certainly, BRANCH in that case should be your current branch. If you
want to merge a different branch into your current branch first update
that non-current branch and then merge::
- $ git fetch origin v1:v1 # Update v1
- $ git pull --rebase origin v2 # Update the current branch v2 using
- # rebase instead of merge
+ $ git fetch origin v1:v1 # Update v1
+ $ git pull --rebase origin v2 # Update the current branch v2 using
+ # rebase instead of merge
+ $ git merge v1
+
+If you have not yet pushed commits on ``v1``, though, the scenario has
+to become a bit more complex. Git refuses to update
+non-fast-forwardable branch, and you don't want to do force-pull
+because that would remove your non-pushed commits and you would need
+to recover. So you want to rebase ``v1`` but you cannot rebase
+non-current branch. Hence, checkout ``v1`` and rebase it before
+merging::
+
+ $ git checkout v1
+ $ git pull --rebase origin v1
+ $ git checkout v2
+ $ git pull --rebase origin v2
$ git merge v1
+It is possible to configure git to make it fetch/pull a few branches
+or all branches at once, so you can simply run
+
+::
+
+ $ git pull origin
+
+or even
+
+::
+
+ $ git pull
+
+Push
+''''
+
+Pushing is a bit simpler. There is only one command ``push``. When you
+run
+
+::
+
+ $ git push origin v1 v2
+
+git guesses (knowing upstream remote branches) that you really want
+
+::
+
+ $ git push origin v1:v1 v2:v2
+
+Git pushes commits to the remote repo and updates remote branches. Git
+refuses to push commits that aren't fast-forwardable. You can
+force-push anyway, but please remember - you can force-push to your
+own repositories but don't force-push to public or shared repos. If
+you find git refuses to push commits that aren't fast-forwardable,
+better fetch and merge commits from the remote repo (or rebase your
+commits on top of the fetched commits), then push. Only force-push if
+you know what you do and why you do it. See the section `Commit
+editing and caveats`_ below.
+
+It is possible to configure git to make it push a few branches or all
+branches at once, so you can simply run
+
+::
+
+ $ git push origin
+
+or even
+
+::
+
+ $ git push
+
+Git refuses to push a branch if it's the current branch in the remote
+non-bare repository: git refuses to update remote working directory.
+You really should push only to bare repositories. For non-bare
+repositories git prefers pull-based workflow.
+
+When you want to deploy code on a remote host and can only use push
+(because your workstation is behind a firewall and you cannot pull
+from it) you do that in two steps using two repositories: you push
+from the workstation to a bare repo on the remote host, ssh to the
+remote host and pull from the bare repo to a non-bare deployment repo.
+
+Tags
+''''
+
+Git automatically fetches tags that point to commits being fetched
+during fetch/pull. To fetch all tags (and commits they point to) run
+``git fetch --tags origin``. To fetch some specific tags fetch them
+explicitly::
+
+ $ git fetch origin tag TAG1 tag TAG2...
+
+For example::
+
+ $ git fetch origin tag 1.4.2 tag 2.1.7
+
+Git doesn't automatically pushes tags. That allows you to have private
+tags (lightweight tags are also private for a repo, they cannot be
+pushed). To push tags list them explicitly::
+
+ $ git push origin tag 1.4.2
+ $ git push origin v1 v2 tag 2.1.7
+
+Don't move tags with ``git tag -f`` after they have been published.
+
Commit editing and caveats
==========================
A warning not to edit published (pushed) commits also appears in
-documentation but it's also repeated here as it's very important.
+documentation but it's repeated here anyway as it's very important.
It is possible to recover from forced push but it's PITA for the
entire team. Please avoid it.
been pushed yet. You can even push commits to your own (backup) repo,
edit them later and force-push edited commits to replace what has
already been pushed. Not a problem until commits are in a public
-repository.
+or shared repository.
Undo
====
-TODO: describe undo strategies: git reset, git revert, git checkout,
-git reflog. "Commit early, commit often".
+Whatever you do, don't panic. Almost anything in git can be undone.
+``git checkout``, for example, can be used to restore the content of
+file(s) to that one of a commit. Like this::
+
+ git checkout HEAD~ README
+
+The commands restores the contente of README file to the last but one
+commit in the current branch. By default a commit ID is simple HEAD;
+i.e. ``git checkout README`` restores README to the latest commit.
+
+(Do not use ``git checkout`` to view a content of a file in a commit,
+use ``git cat-file -p``; e.g. ``git cat-file -p HEAD~:path/to/README``).
+
+TODO: describe undo strategies: git reset, git reflog, git revert.
+"Commit early, commit often".
How to undo a merge
-https://kernel.org/pub/software/scm/git/docs/howto/revert-a-faulty-merge.html
+https://www.kernel.org/pub/software/scm/git/docs/howto/revert-a-faulty-merge.html
+
+
+Merge or rebase?
+================
+
+Internet is full of heated discussions on the topic: "merge or
+rebase?" Most of them are meaningless. When a DVCS is being used in a
+big team with a big and complex project with many branches there is
+simply no way to avoid merges. So the question's diminished to
+"whether to use rebase, and if yes - when to use rebase?" Considering
+that it is very much recommended not to rebase published commits the
+question's diminished even further: "whether to use rebase on
+non-pushed commits?"
+
+That small question is for the team to decide. The author of the PEP
+recommends to use rebase when pulling, i.e. always do ``git pull
+--rebase`` or even configure automatic setup of rebase for every new
+branch::
+
+ $ git config branch.autosetuprebase true
+
+and configure rebase for existing branches::
+
+ $ git config branch.NAME.rebase true
+
+For example::
+
+ $ git config branch.v1.rebase true
+ $ git config branch.v2.rebase true
+
+After that ``git pull origin v2`` becomes equivalent to ``git pull
+--rebase origin v2``.
+
+In case when merge is preferred it is recommended to create new
+commits in a separate feature or topic branch while using rebase to
+update the mainline branch. When the topic branch is ready merge it
+into mainline. To avoid a tedious task of resolving large number of
+conflicts at once you can merge the topic branch to the mainline from
+time to time and switch back to the topic branch to continue working
+on it. The entire workflow would be something like::
+
+ $ git checkout -b issue-42 # create a new issue branch and switch to it
+ ...edit/test/commit...
+ $ git checkout v2
+ $ git pull --rebase origin v2 # update v2 from the upstream
+ $ git merge issue-42
+ $ git branch -d issue-42 # delete the topic branch
+ $ git push origin v2
+
+When the topic branch is deleted only the label is removed, commits
+are stayed in the database, they are now merged into v2::
+
+ o--o--o--o--o--M--< v2 - the mainline branch
+ \ /
+ --*--*--* - the topic branch, now unnamed
+
+The topic branch is deleted to avoid cluttering branch namespace with
+small topic branches. Information on what issue was fixed or what
+feature was implemented should be in the commit messages.
+
+
+Null-merges
+===========
+
+Git has a builtin merge strategy for what Python core developers call
+"null-merge"::
+
+ $ git merge -s ours v1 # null-merge v1 into v2
+
+
+ReReRe
+======
+
+https://git-scm.com/book/en/Git-Tools-Rerere
Advanced topics
TODO: describe crlf configuration and .gitattributes.
-Null-merges
-===========
-
-Git has a builtin strategy for what Python core developers call
-"null-merge"::
-
- $ git merge -s ours v1 # null-merge v1 into v2
-
-
Database maintenance
====================
TODO: dangling objects, git gc, git repack.
+https://gcc.gnu.org/ml/gcc/2007-12/msg00165.html
Tips and tricks
===============
+TODO: sticky options; example: git grep -O.
+
+TODO: tricky options; example: git log -p3.
+
TODO: bash/zsh completion, bash/zsh prompt.
+https://git.kernel.org/cgit/git/git.git/tree/contrib/completion
+
+
+git on server
+=============
+
+TODO: anonymous access; git over ssh; gitolite; gitweb; cgit; gitlab.
+
+http://gitolite.com/gitolite/index.html
+
+https://git.kernel.org/cgit/git/git.git/tree/gitweb
+http://git.zx2c4.com/cgit/
From Mercurial to git
=====================
projects / git-wiki.git / blobdiff