X-Git-Url: https://git.phdru.name/?a=blobdiff_plain;f=pep-git.txt;h=bb1d77b73f63e7e7e4036cdaf555afa96deaca6e;hb=3c69930122749e2c433afedec102dbae698d88d3;hp=d6c46763b81ad8fbf7f0c9fcc77d4dae75b88cc0;hpb=df380c17cca5f6a0ececaf1a737653d99ba38d9f;p=git-wiki.git
diff --git a/pep-git.txt b/pep-git.txt
index d6c4676..bb1d77b 100644
--- a/pep-git.txt
+++ b/pep-git.txt
@@ -62,7 +62,7 @@ many different languages. Download Russian translation from `GArik
Offline documentation
---------------------
-Git has builtin help: run ``git help TOPIC``. For example, run
+Git has builtin help: run ``git help $TOPIC``. For example, run
``git help git`` or ``git help help``.
@@ -85,9 +85,8 @@ MacOS X: use git installed with `XCode
`_ or
install git with `Homebrew `_: ``brew install git``.
-`git-cola `_ is a sleek and
-powerful Git GUI written in Python and GPL licensed. Linux, Windows,
-MacOS X.
+`git-cola `_ is a Git GUI
+written in Python and GPL licensed. Linux, Windows, MacOS X.
`TortoiseGit `_ is a Windows Shell Interface
to Git based on TortoiseSVN; open source.
@@ -120,11 +119,11 @@ done something like that::
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
+its upstream remote-tracking 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.
+remotes/origin/v1 as its upstream remote-tracking branch.
The same result can be achieved with commands::
@@ -132,9 +131,9 @@ The same result can be achieved with commands::
$ cd python
$ 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.
+The last command creates a new local branch v2, sets remotes/origin/v2
+as its upstream remote-tracking branch and checks it out into the
+working directory.
Branches and branches
@@ -143,90 +142,87 @@ Branches and branches
Git terminology can be a bit misleading. Take, for example, the term
"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. Lines of commits
-are by itself unnamed and are usually only lengthening and merging.
+assigned to a line of commits. It is important to distinguish when 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
-=====================================
+Remote repositories and remote branches
+=======================================
-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-tracking branches are branches (pointers to commits) 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). Remote-tracking branches live
+under ``remotes/$REMOTE`` namespaces, e.g. ``remotes/origin/v2``.
-Remote branches, on the other hand, are branches (pointers to commits)
-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). Remote branches
-live under ``remotes/REMOTE`` namespaces, e.g. ``remotes/origin/v2``.
-
-To see the status of remote branches run::
+To see the status of remote-tracking branches run::
$ git branch -rv
-To see local and remote branches (and tags) pointing to commits::
+To see local and remote-tracking branches (and tags) pointing to
+commits::
$ git log --decorate
-You never do your own development on remote branches. You create a
-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.
+You never do your own development on remote-tracking branches. You
+create a local branch that has a remote branch as upstream and do
+development on that local branch. On push git pushes commits to the
+remote repo and updates remote-tracking branches, on pull git fetches
+commits from the remote repo, updates remote-tracking 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, creates a local branch
-``v1``, configure it to track upstream remotes/origin/v1 branch and
-checks out ``v1`` into the working directory.
+directory ``python``, creates remote-tracking 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
-----------------------------------
+Updating local and remote-tracking branches
+-------------------------------------------
There is a major difference between
::
- $ git fetch REMOTE BRANCH
+ $ git fetch $REMOTE $BRANCH
and
::
- $ git fetch REMOTE BRANCH:BRANCH
+ $ 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 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 and updates
+remote-tracking branch.
-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 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-tracking 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 internally by ``git pull``.
::
- $ git pull REMOTE BRANCH
+ $ git pull $REMOTE $BRANCH
is equivalent to
::
- $ git fetch REMOTE BRANCH
- $ git merge FETCH_HEAD # FETCH_HEAD is a literal here
+ $ git fetch $REMOTE $BRANCH
+ $ git merge FETCH_HEAD
-Certainly, BRANCH in that case should be your current branch. If you
+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::
@@ -262,6 +258,10 @@ or even
$ git pull
+Default remote repository for fetching/pulling is origin. Default set
+of references to fetch is calculated using matching algorithm: git
+fetches all branches having the same name on both ends.
+
Push
''''
@@ -272,17 +272,16 @@ run
$ git push origin v1 v2
-git guesses (knowing upstream remote branches) that you really want
-
-::
+git pushes local v1 to remote v1 and local v2 to remote v2. The same
+as::
$ 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,
+Git pushes commits to the remote repo and updates remote-tracking
+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
@@ -301,6 +300,21 @@ or even
$ git push
+Default remote repository for pushing is origin. Default set
+of references to push in git before 2.0 is calculated using matching
+algorithm: git pushes all branches having the same name on both ends.
+Default set of references to push in git 2.0+ is calculated using
+simple algorithm: git pushes the current branch back to its
+@{upstream}.
+
+To configure git before 2.0 to the new behaviour run::
+
+$ git config push.default simple
+
+To configure git 2.0+ to the old behaviour run::
+
+$ git config push.default matching
+
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
@@ -312,6 +326,11 @@ 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.
+That changed in git 2.3, but see `the blog post
+`_
+for caveats; in 2.4 the push-to-deploy feature was `further improved
+`_.
+
Tags
''''
@@ -320,7 +339,7 @@ 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...
+ $ git fetch origin tag $TAG1 tag $TAG2...
For example::
@@ -333,7 +352,8 @@ 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.
+Don't move tags with ``git tag -f`` or remove tags with ``git tag -d``
+after they have been published.
Commit editing and caveats
@@ -346,14 +366,14 @@ It is possible to recover from forced push but it's PITA for the
entire team. Please avoid it.
To see what commits have not been published yet compare the head of the
-branch with its upstream remote branch::
+branch with its upstream remote-tracking branch::
$ git log origin/v2..
$ git log origin/v1..v1
-For every branch that has an upstream remote branch git maintains an
-alias @{upstream} (short version @{u}), so the commands above can be
-given as::
+For every branch that has an upstream remote-tracking branch git
+maintains an alias @{upstream} (short version @{u}), so the commands
+above can be given as::
$ git log @{u}..
$ git log v1@{u}..v1
@@ -381,11 +401,125 @@ 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: restore file's content
+------------------------------------
+
+``git checkout``, for example, can be used to restore the content of
+file(s) to that one of a commit. Like this::
-How to undo a merge
-https://www.kernel.org/pub/software/scm/git/docs/howto/revert-a-faulty-merge.html
+ git checkout HEAD~ README
+
+The commands restores the contents of README file to the last but one
+commit in the current branch. By default the commit ID is simply 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``).
+
+git reset: remove (non-pushed) commits
+--------------------------------------
+
+``git reset`` moves the head of the current branch. The head can be
+moved to point to any commit but it's often used to remove a commit or
+a few (preferably, non-pushed ones) from the top of the branch - that
+is, to move the branch backward in order to undo a few (non-pushed)
+commits.
+
+``git reset`` has three modes of operation - soft, hard and mixed.
+Default is mixed. ProGit `explains
+`_ the
+difference very clearly. Bare repositories don't have indices or
+working trees so in a bare repo only soft reset is possible.
+
+Unstaging
+'''''''''
+
+Mixed mode reset with a path or paths can be used to unstage changes -
+that is, to remove from index changes added with ``git add`` for
+committing. See `The Book
+`_ for details
+about unstaging and other undo tricks.
+
+git reflog: reference log
+-------------------------
+
+Removing commits with ``git reset`` or moving the head of a branch
+sounds dangerous and it is. But there is a way to undo: another
+reset back to the original commit. Git doesn't remove commits
+immediately; unreferenced commits (in git terminology they are called
+"dangling commits") stay in the database for some time (default is two
+weeks) so you can reset back to it or create a new branch pointing to
+the original commit.
+
+For every move of a branch's head - with ``git commit``, ``git
+checkout``, ``git fetch``, ``git pull``, ``git rebase``, ``git reset``
+and so on - git stores a reference log (reflog for short). For every
+move git stores where the head was. Command ``git reflog`` can be used
+to view (and manipulate) the log.
+
+In addition to the moves of the head of every branch git stores the
+moves of the HEAD - a symbolic reference that (usually) names the
+current branch. HEAD is changed with ``git checkout $BRANCH``.
+
+By default ``git reflog`` shows the moves of the HEAD, i.e. the
+command is equivalent to ``git reflog HEAD``. To show the moves of the
+head of a branch use the command ``git reflog $BRANCH``.
+
+So to undo a ``git reset`` lookup the original commit in ``git
+reflog``, verify it with ``git show`` or ``git log`` and run ``git
+reset $COMMIT_ID``. Git stores the move of the branch's head in
+reflog, so you can undo that undo later again.
+
+In a more complex situation you'd want to move some commits along with
+resetting the head of the branch. Cherry-pick them to the new branch.
+For example, if you want to reset the branch ``v2`` back to the
+original commit but preserve two commits created in the current branch
+do something like::
+
+ $ git branch save-v2 # create a new branch saving v2
+ $ git reflog # find the original place of v2
+ $ git reset $COMMIT_ID
+ $ git cherry-pick save-v2~ save-v2
+ $ git branch -D save-v2 # remove temporary branch
+
+git revert: revert a commit
+---------------------------
+
+``git revert`` reverts a commit or commits, that is, it creates a new
+commit or commits that reverts the effects of the given commits. It's
+the only way to undo published commits (``git commit --amend``, ``git
+rebase`` and ``git reset`` change the branch in non-fast-forwardable
+ways so they should only be used for non-pushed commits.)
+
+There is a problem with reverting a merge commit. ``git revert`` can
+undo the code created by the merge commit but it cannot undo the fact
+of merge. See the discussion `How to revert a faulty merge
+`_.
+
+One thing that cannot be undone
+-------------------------------
+
+Whatever you undo, there is one thing that cannot be undone -
+overwritten uncommitted changes. Uncommitted changes don't belong to
+git so git cannot help preserving them.
+
+Most of the time git warns you when you're going to execute a command
+that overwrites uncommitted changes. Git warns you when you try to
+switch branches with ``git checkout``. It warns you when you're going
+to rebase with non-clean working tree. It refuses to pull new commits
+over non-committed files.
+
+But there are commands that do exactly that - overwrite files in the
+working tree. Commands like ``git checkout $PATHs`` or ``git reset
+--hard`` silently overwrite files including your uncommitted changes.
+
+With that in mind you can understand the stance "commit early, commit
+often". Commit as often as possible. Commit on every save in your
+editor or IDE. You can edit your commits before pushing - change,
+reorder, combine, remove. But save your changes in git database,
+either commit changes or at least stash them with ``git stash``.
Merge or rebase?
@@ -405,11 +539,11 @@ 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
+ $ git config branch.autosetuprebase always
and configure rebase for existing branches::
- $ git config branch.NAME.rebase true
+ $ git config branch.$NAME.rebase true
For example::
@@ -427,7 +561,7 @@ 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 and switch to a new branch
+ $ 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
@@ -438,9 +572,9 @@ on it. The entire workflow would be something like::
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 - it is the mainline branch
+ o--o--o--o--o--M--< v2 - the mainline branch
\ /
- --*--*--* - it is the topic branch, now unnamed
+ --*--*--* - 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
@@ -450,16 +584,35 @@ feature was implemented should be in the commit messages.
Null-merges
===========
-Git has a builtin strategy for what Python core developers call
+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
-======
+Advanced configuration
+======================
-https://git-scm.com/book/en/Git-Tools-Rerere
+Line endings
+------------
+
+Git has builtin mechanisms to handle line endings between platforms
+with different EOL styles. To allow git to do CRLF conversion assign
+``text`` attribute to files using `.gitattributes
+`_.
+For files that have to have specific line ending assign ``eol``
+attribute. For binary files the attribute is, naturally, ``binary``.
+
+For example::
+
+ $ cat .gitattributes
+ *.py text
+ *.txt text
+ *.png binary
+ /readme.txt eol=CRLF
+
+To check what attributes git uses for files use ``git check-attr``
+command.
Advanced topics
@@ -476,15 +629,10 @@ Staging area aka index is a distinguishing feature of git. See
Wiki.
-Advanced configuration
-======================
-
-Line endings
-------------
-
-Git has builtin mechanisms to handle line endings.
+ReReRe
+======
-TODO: describe crlf configuration and .gitattributes.
+https://git-scm.com/book/en/Git-Tools-Rerere
Database maintenance
@@ -492,13 +640,20 @@ Database maintenance
TODO: dangling objects, git gc, git repack.
+https://gcc.gnu.org/ml/gcc/2007-12/msg00165.html
+
+http://vcscompare.blogspot.ru/2008/06/git-repack-parameters.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
@@ -506,6 +661,11 @@ 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
=====================