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diff --git a/Documentation/git-checkout.txt b/Documentation/git-checkout.txt new file mode 100644 index 0000000000..33ad2adf5c --- /dev/null +++ b/Documentation/git-checkout.txt @@ -0,0 +1,479 @@ +git-checkout(1) +=============== + +NAME +---- +git-checkout - Checkout a branch or paths to the working tree + +SYNOPSIS +-------- +[verse] +'git checkout' [-q] [-f] [-m] [<branch>] +'git checkout' [-q] [-f] [-m] --detach [<branch>] +'git checkout' [-q] [-f] [-m] [--detach] <commit> +'git checkout' [-q] [-f] [-m] [[-b|-B|--orphan] <new_branch>] [<start_point>] +'git checkout' [-f|--ours|--theirs|-m|--conflict=<style>] [<tree-ish>] [--] <paths>... +'git checkout' [-p|--patch] [<tree-ish>] [--] [<paths>...] + +DESCRIPTION +----------- +Updates files in the working tree to match the version in the index +or the specified tree. If no paths are given, 'git checkout' will +also update `HEAD` to set the specified branch as the current +branch. + +'git checkout' <branch>:: + To prepare for working on <branch>, switch to it by updating + the index and the files in the working tree, and by pointing + HEAD at the branch. Local modifications to the files in the + working tree are kept, so that they can be committed to the + <branch>. ++ +If <branch> is not found but there does exist a tracking branch in +exactly one remote (call it <remote>) with a matching name, treat as +equivalent to ++ +------------ +$ git checkout -b <branch> --track <remote>/<branch> +------------ ++ +You could omit <branch>, in which case the command degenerates to +"check out the current branch", which is a glorified no-op with a +rather expensive side-effects to show only the tracking information, +if exists, for the current branch. + +'git checkout' -b|-B <new_branch> [<start point>]:: + + Specifying `-b` causes a new branch to be created as if + linkgit:git-branch[1] were called and then checked out. In + this case you can use the `--track` or `--no-track` options, + which will be passed to 'git branch'. As a convenience, + `--track` without `-b` implies branch creation; see the + description of `--track` below. ++ +If `-B` is given, <new_branch> is created if it doesn't exist; otherwise, it +is reset. This is the transactional equivalent of ++ +------------ +$ git branch -f <branch> [<start point>] +$ git checkout <branch> +------------ ++ +that is to say, the branch is not reset/created unless "git checkout" is +successful. + +'git checkout' --detach [<branch>]:: +'git checkout' [--detach] <commit>:: + + Prepare to work on top of <commit>, by detaching HEAD at it + (see "DETACHED HEAD" section), and updating the index and the + files in the working tree. Local modifications to the files + in the working tree are kept, so that the resulting working + tree will be the state recorded in the commit plus the local + modifications. ++ +When the <commit> argument is a branch name, the `--detach` option can +be used to detach HEAD at the tip of the branch (`git checkout +<branch>` would check out that branch without detaching HEAD). ++ +Omitting <branch> detaches HEAD at the tip of the current branch. + +'git checkout' [-p|--patch] [<tree-ish>] [--] <pathspec>...:: + + When <paths> or `--patch` are given, 'git checkout' does *not* + switch branches. It updates the named paths in the working tree + from the index file or from a named <tree-ish> (most often a + commit). In this case, the `-b` and `--track` options are + meaningless and giving either of them results in an error. The + <tree-ish> argument can be used to specify a specific tree-ish + (i.e. commit, tag or tree) to update the index for the given + paths before updating the working tree. ++ +The index may contain unmerged entries because of a previous failed merge. +By default, if you try to check out such an entry from the index, the +checkout operation will fail and nothing will be checked out. +Using `-f` will ignore these unmerged entries. The contents from a +specific side of the merge can be checked out of the index by +using `--ours` or `--theirs`. With `-m`, changes made to the working tree +file can be discarded to re-create the original conflicted merge result. + +OPTIONS +------- +-q:: +--quiet:: + Quiet, suppress feedback messages. + +-f:: +--force:: + When switching branches, proceed even if the index or the + working tree differs from HEAD. This is used to throw away + local changes. ++ +When checking out paths from the index, do not fail upon unmerged +entries; instead, unmerged entries are ignored. + +--ours:: +--theirs:: + When checking out paths from the index, check out stage #2 + ('ours') or #3 ('theirs') for unmerged paths. + +-b <new_branch>:: + Create a new branch named <new_branch> and start it at + <start_point>; see linkgit:git-branch[1] for details. + +-B <new_branch>:: + Creates the branch <new_branch> and start it at <start_point>; + if it already exists, then reset it to <start_point>. This is + equivalent to running "git branch" with "-f"; see + linkgit:git-branch[1] for details. + +-t:: +--track:: + When creating a new branch, set up "upstream" configuration. See + "--track" in linkgit:git-branch[1] for details. ++ +If no '-b' option is given, the name of the new branch will be +derived from the remote-tracking branch, by looking at the local part of +the refspec configured for the corresponding remote, and then stripping +the initial part up to the "*". +This would tell us to use "hack" as the local branch when branching +off of "origin/hack" (or "remotes/origin/hack", or even +"refs/remotes/origin/hack"). If the given name has no slash, or the above +guessing results in an empty name, the guessing is aborted. You can +explicitly give a name with '-b' in such a case. + +--no-track:: + Do not set up "upstream" configuration, even if the + branch.autosetupmerge configuration variable is true. + +-l:: + Create the new branch's reflog; see linkgit:git-branch[1] for + details. + +--detach:: + Rather than checking out a branch to work on it, check out a + commit for inspection and discardable experiments. + This is the default behavior of "git checkout <commit>" when + <commit> is not a branch name. See the "DETACHED HEAD" section + below for details. + +--orphan <new_branch>:: + Create a new 'orphan' branch, named <new_branch>, started from + <start_point> and switch to it. The first commit made on this + new branch will have no parents and it will be the root of a new + history totally disconnected from all the other branches and + commits. ++ +The index and the working tree are adjusted as if you had previously run +"git checkout <start_point>". This allows you to start a new history +that records a set of paths similar to <start_point> by easily running +"git commit -a" to make the root commit. ++ +This can be useful when you want to publish the tree from a commit +without exposing its full history. You might want to do this to publish +an open source branch of a project whose current tree is "clean", but +whose full history contains proprietary or otherwise encumbered bits of +code. ++ +If you want to start a disconnected history that records a set of paths +that is totally different from the one of <start_point>, then you should +clear the index and the working tree right after creating the orphan +branch by running "git rm -rf ." from the top level of the working tree. +Afterwards you will be ready to prepare your new files, repopulating the +working tree, by copying them from elsewhere, extracting a tarball, etc. + +--ignore-skip-worktree-bits:: + In sparse checkout mode, `git checkout -- <paths>` would + update only entries matched by <paths> and sparse patterns + in $GIT_DIR/info/sparse-checkout. This option ignores + the sparse patterns and adds back any files in <paths>. + +-m:: +--merge:: + When switching branches, + if you have local modifications to one or more files that + are different between the current branch and the branch to + which you are switching, the command refuses to switch + branches in order to preserve your modifications in context. + However, with this option, a three-way merge between the current + branch, your working tree contents, and the new branch + is done, and you will be on the new branch. ++ +When a merge conflict happens, the index entries for conflicting +paths are left unmerged, and you need to resolve the conflicts +and mark the resolved paths with `git add` (or `git rm` if the merge +should result in deletion of the path). ++ +When checking out paths from the index, this option lets you recreate +the conflicted merge in the specified paths. + +--conflict=<style>:: + The same as --merge option above, but changes the way the + conflicting hunks are presented, overriding the + merge.conflictstyle configuration variable. Possible values are + "merge" (default) and "diff3" (in addition to what is shown by + "merge" style, shows the original contents). + +-p:: +--patch:: + Interactively select hunks in the difference between the + <tree-ish> (or the index, if unspecified) and the working + tree. The chosen hunks are then applied in reverse to the + working tree (and if a <tree-ish> was specified, the index). ++ +This means that you can use `git checkout -p` to selectively discard +edits from your current working tree. See the ``Interactive Mode'' +section of linkgit:git-add[1] to learn how to operate the `--patch` mode. + +<branch>:: + Branch to checkout; if it refers to a branch (i.e., a name that, + when prepended with "refs/heads/", is a valid ref), then that + branch is checked out. Otherwise, if it refers to a valid + commit, your HEAD becomes "detached" and you are no longer on + any branch (see below for details). ++ +As a special case, the `"@{-N}"` syntax for the N-th last branch/commit +checks out branches (instead of detaching). You may also specify +`-` which is synonymous with `"@{-1}"`. ++ +As a further special case, you may use `"A...B"` as a shortcut for the +merge base of `A` and `B` if there is exactly one merge base. You can +leave out at most one of `A` and `B`, in which case it defaults to `HEAD`. + +<new_branch>:: + Name for the new branch. + +<start_point>:: + The name of a commit at which to start the new branch; see + linkgit:git-branch[1] for details. Defaults to HEAD. + +<tree-ish>:: + Tree to checkout from (when paths are given). If not specified, + the index will be used. + + + +DETACHED HEAD +------------- +HEAD normally refers to a named branch (e.g. 'master'). Meanwhile, each +branch refers to a specific commit. Let's look at a repo with three +commits, one of them tagged, and with branch 'master' checked out: + +------------ + HEAD (refers to branch 'master') + | + v +a---b---c branch 'master' (refers to commit 'c') + ^ + | + tag 'v2.0' (refers to commit 'b') +------------ + +When a commit is created in this state, the branch is updated to refer to +the new commit. Specifically, 'git commit' creates a new commit 'd', whose +parent is commit 'c', and then updates branch 'master' to refer to new +commit 'd'. HEAD still refers to branch 'master' and so indirectly now refers +to commit 'd': + +------------ +$ edit; git add; git commit + + HEAD (refers to branch 'master') + | + v +a---b---c---d branch 'master' (refers to commit 'd') + ^ + | + tag 'v2.0' (refers to commit 'b') +------------ + +It is sometimes useful to be able to checkout a commit that is not at +the tip of any named branch, or even to create a new commit that is not +referenced by a named branch. Let's look at what happens when we +checkout commit 'b' (here we show two ways this may be done): + +------------ +$ git checkout v2.0 # or +$ git checkout master^^ + + HEAD (refers to commit 'b') + | + v +a---b---c---d branch 'master' (refers to commit 'd') + ^ + | + tag 'v2.0' (refers to commit 'b') +------------ + +Notice that regardless of which checkout command we use, HEAD now refers +directly to commit 'b'. This is known as being in detached HEAD state. +It means simply that HEAD refers to a specific commit, as opposed to +referring to a named branch. Let's see what happens when we create a commit: + +------------ +$ edit; git add; git commit + + HEAD (refers to commit 'e') + | + v + e + / +a---b---c---d branch 'master' (refers to commit 'd') + ^ + | + tag 'v2.0' (refers to commit 'b') +------------ + +There is now a new commit 'e', but it is referenced only by HEAD. We can +of course add yet another commit in this state: + +------------ +$ edit; git add; git commit + + HEAD (refers to commit 'f') + | + v + e---f + / +a---b---c---d branch 'master' (refers to commit 'd') + ^ + | + tag 'v2.0' (refers to commit 'b') +------------ + +In fact, we can perform all the normal Git operations. But, let's look +at what happens when we then checkout master: + +------------ +$ git checkout master + + HEAD (refers to branch 'master') + e---f | + / v +a---b---c---d branch 'master' (refers to commit 'd') + ^ + | + tag 'v2.0' (refers to commit 'b') +------------ + +It is important to realize that at this point nothing refers to commit +'f'. Eventually commit 'f' (and by extension commit 'e') will be deleted +by the routine Git garbage collection process, unless we create a reference +before that happens. If we have not yet moved away from commit 'f', +any of these will create a reference to it: + +------------ +$ git checkout -b foo <1> +$ git branch foo <2> +$ git tag foo <3> +------------ + +<1> creates a new branch 'foo', which refers to commit 'f', and then +updates HEAD to refer to branch 'foo'. In other words, we'll no longer +be in detached HEAD state after this command. + +<2> similarly creates a new branch 'foo', which refers to commit 'f', +but leaves HEAD detached. + +<3> creates a new tag 'foo', which refers to commit 'f', +leaving HEAD detached. + +If we have moved away from commit 'f', then we must first recover its object +name (typically by using git reflog), and then we can create a reference to +it. For example, to see the last two commits to which HEAD referred, we +can use either of these commands: + +------------ +$ git reflog -2 HEAD # or +$ git log -g -2 HEAD +------------ + +EXAMPLES +-------- + +. The following sequence checks out the `master` branch, reverts +the `Makefile` to two revisions back, deletes hello.c by +mistake, and gets it back from the index. ++ +------------ +$ git checkout master <1> +$ git checkout master~2 Makefile <2> +$ rm -f hello.c +$ git checkout hello.c <3> +------------ ++ +<1> switch branch +<2> take a file out of another commit +<3> restore hello.c from the index ++ +If you want to check out _all_ C source files out of the index, +you can say ++ +------------ +$ git checkout -- '*.c' +------------ ++ +Note the quotes around `*.c`. The file `hello.c` will also be +checked out, even though it is no longer in the working tree, +because the file globbing is used to match entries in the index +(not in the working tree by the shell). ++ +If you have an unfortunate branch that is named `hello.c`, this +step would be confused as an instruction to switch to that branch. +You should instead write: ++ +------------ +$ git checkout -- hello.c +------------ + +. After working in the wrong branch, switching to the correct +branch would be done using: ++ +------------ +$ git checkout mytopic +------------ ++ +However, your "wrong" branch and correct "mytopic" branch may +differ in files that you have modified locally, in which case +the above checkout would fail like this: ++ +------------ +$ git checkout mytopic +error: You have local changes to 'frotz'; not switching branches. +------------ ++ +You can give the `-m` flag to the command, which would try a +three-way merge: ++ +------------ +$ git checkout -m mytopic +Auto-merging frotz +------------ ++ +After this three-way merge, the local modifications are _not_ +registered in your index file, so `git diff` would show you what +changes you made since the tip of the new branch. + +. When a merge conflict happens during switching branches with +the `-m` option, you would see something like this: ++ +------------ +$ git checkout -m mytopic +Auto-merging frotz +ERROR: Merge conflict in frotz +fatal: merge program failed +------------ ++ +At this point, `git diff` shows the changes cleanly merged as in +the previous example, as well as the changes in the conflicted +files. Edit and resolve the conflict and mark it resolved with +`git add` as usual: ++ +------------ +$ edit frotz +$ git add frotz +------------ + +GIT +--- +Part of the linkgit:git[1] suite |