This Informational PEP collects information about git. There is, of
course, a lot of documentation for git, so the PEP concentrates on
-more complex issues, topics and scenarios.
+more complex issues, scenarios and topics.
The plan is to extend the PEP in the future collecting information
about equivalence of Mercurial and git scenarios to help migrating
---------------------
This simple code is often appears in documentation, but it is
-important so let repeat it here::
+important so let repeat it here. Git marks every commit with author
+and commiter names/emails, so configure your real name and preferred
+email::
$ git config --global user.name "User Name"
$ git config --global user.email user.name@example.org
-Put your real name and preferred email.
-
Examples in this PEP
====================
=====================
Git terminology can be a bit misleading. Take, for example, the term
-"branch". In git it has two meanings. A branch is a directed chain of
-commits (possible with merges). And a branch is a label or a pointer
+"branch". In git it has two meanings. A branch is a directed line of
+commits (possibly with merges). And a branch is a label or a pointer
assigned to a line of commits. It is important to differentiate when
-you talk about commits and when about their labels. Chains of commits
-are unnamed and are usually only lengthening. Labels, on the other
-hand, can be created, moved, renamed and deleted freely.
+you talk about commits and when about their labels. Lines of commits
+are by itself unnamed and are usually only lengthening and merging.
+Labels, on the other hand, can be created, moved, renamed and deleted
+freely.
Remote repository and remote branches
=====================================
-Another example of misleading terminology. A remote repository is
-really remote, you access it via network (well, a remote repository
-can be on your local disk, but it's still remote because it's not the
-current repo).
+Another example of slightly misleading terminology. Remote
+repositories are really remote, you access them via network (well, a
+remote repository can be on your local disk, but it's still remote
+because it's not the current repo).
Remote branches, on the other hand, are branches (pointers to commits)
-in your local repository. They are there for git to remember what
+in your local repository. They are there for you to remember what
branches and commits have been pulled from and pushed to what remote
-repos (you can pull from and push to many remotes).
+repos (you can pull from and push to many remotes). Remote branches
+live under ``remotes/REMOTE`` namespaces, e.g. ``remotes/origin/v2``.
-To see the status of remote branches::
+To see the status of remote branches run::
$ git branch -rv
-To see local and remote branches (and tags) pointing to commits run::
+To see local and remote branches (and tags) pointing to commits::
$ git log --decorate
directory ``python``, creates remote branches and checks out branch
``v1`` into the working directory.
+Updating local and remote branches
+----------------------------------
+
+There is a major difference between
+
+::
+
+ $ git fetch REMOTE BRANCH
+
+and
+
+::
+
+ $ git fetch REMOTE BRANCH:BRANCH
+
+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 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
+branch BRANCH and its upstream remote branch. But it refuses to update
+branches in case of non-fast-forward. And it refuses to update the
+current branch.
+
+The first command is used internall by ``git pull``.
+
+::
+
+ $ git pull REMOTE BRANCH
+
+is equivalent to
+
+::
+
+ $ git fetch REMOTE BRANCH
+ $ 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 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. 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.
+
+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 NAME1 tag NAME2...
+
+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 tag(s) list them explicitly::
+
+ $ git push origin tag 1.4.2
+ $ git push origin v1 v2 tag 2.1.7
+
Commit editing and caveats
==========================
repository.
+Undo
+====
+
+TODO: describe undo strategies: git reset, git revert, git checkout,
+git reflog. "Commit early, commit often".
+
+How to undo a merge
+https://kernel.org/pub/software/scm/git/docs/howto/revert-a-faulty-merge.html
+
+
+Advanced topics
+===============
+
+Staging area
+------------
+
+Staging area aka index is a distinguishing feature of git. See
+`WhatIsTheIndex
+<https://git.wiki.kernel.org/index.php/WhatIsTheIndex>`_ and
+`IndexCommandQuickref
+<https://git.wiki.kernel.org/index.php/IndexCommandQuickref>`_ in Git
+Wiki.
+
+
+Merge or rebase?
+================
+
+
+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
+
+
+ReReRe
+======
+
+https://git-scm.com/book/en/Git-Tools-Rerere
+
+
+Advanced configuration
+======================
+
+Line endings
+------------
+
+Git has builtin mechanisms to handle line endings.
+
+TODO: describe crlf configuration and .gitattributes.
+
+
+Database maintenance
+====================
+
+TODO: dangling objects, git gc, git repack.
+
+
+Tips and tricks
+===============
+
+TODO: bash/zsh completion, bash/zsh prompt.
+
+
+From Mercurial to git
+=====================
+
+Mercurial for Git users https://mercurial.selenic.com/wiki/GitConcepts
+
+https://github.com/felipec/git-remote-hg
+
+https://hg-git.github.io/
+
+
References
==========