X-Git-Url: https://git.phdru.name/?a=blobdiff_plain;f=pep-git.txt;h=51701c9935fcb673cade2b5a89fc8ecfa0548fd4;hb=bb91e98e10aabd0b8ae3972e10333c68e5ca803d;hp=a96594d85db8378e88a126151e47c3b307776a9d;hpb=ad6b3de1dd577b4871f333a6be868c35466e81a0;p=git-wiki.git diff --git a/pep-git.txt b/pep-git.txt index a96594d..51701c9 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``. @@ -119,11 +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:: @@ -131,9 +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 @@ -142,9 +142,9 @@ 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. @@ -152,81 +152,77 @@ freely. 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 pushes commits to the remote repo -and updates remote branches, on pull git fetches commits from the -remote repo, 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 @@ -382,22 +402,29 @@ Undo ==== 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:: 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; +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 +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. @@ -406,16 +433,93 @@ Default is mixed. ProGit `explains 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 changes added with ``git add`` for committing. See -`The Book `_ -for details about unstaging and other undo tricks. +that is, to remove from index changes added with ``git add`` for +committing. See `The Book +`_ for details +about unstaging and other undo tricks. -TODO: describe undo strategies: git reflog, git revert. -"Commit early, commit often". +git reflog: reference log +------------------------- -How to undo a merge -https://www.kernel.org/pub/software/scm/git/docs/howto/revert-a-faulty-merge.html +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? @@ -439,7 +543,7 @@ branch:: and configure rebase for existing branches:: - $ git config branch.NAME.rebase true + $ git config branch.$NAME.rebase true For example:: @@ -486,10 +590,15 @@ Git has a builtin merge strategy for what Python core developers call $ 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. + +TODO: describe crlf configuration and .gitattributes. Advanced topics @@ -506,23 +615,21 @@ 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 ==================== 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 ===============