a summary of the commands:
`git branch`::
- list all branches
+ list all branches.
`git branch <branch>`::
create a new branch named `<branch>`, referencing the same
- point in history as the current branch
+ point in history as the current branch.
`git branch <branch> <start-point>`::
create a new branch named `<branch>`, referencing
`<start-point>`, which may be specified any way you like,
- including using a branch name or a tag name
+ including using a branch name or a tag name.
`git branch -d <branch>`::
- delete the branch `<branch>`; if the branch you are deleting
- points to a commit which is not reachable from the current
- branch, this command will fail with a warning.
+ delete the branch `<branch>`; if the branch is not fully
+ merged in its upstream branch or contained in the current branch,
+ this command will fail with a warning.
`git branch -D <branch>`::
- even if the branch points to a commit not reachable
- from the current branch, you may know that that commit
- is still reachable from some other branch or tag. In that
- case it is safe to use this command to force Git to delete
- the branch.
+ delete the branch `<branch>` irrespective of its merged status.
`git checkout <branch>`::
make the current branch `<branch>`, updating the working
- directory to reflect the version referenced by `<branch>`
+ directory to reflect the version referenced by `<branch>`.
`git checkout -b <new> <start-point>`::
create a new branch `<new>` referencing `<start-point>`, and
check it out.
Modifying the index is easy:
-To update the index with the new contents of a modified file, use
+To update the index with the contents of a new or modified file, use
-------------------------------------------------
$ git add path/to/file
-------------------------------------------------
-To add the contents of a new file to the index, use
-
--------------------------------------------------
-$ git add path/to/file
--------------------------------------------------
-
-To remove a file from the index and from the working tree,
+To remove a file from the index and from the working tree, use
-------------------------------------------------
$ git rm path/to/file
-------------------------------------------------
(See also
-link:howto/setup-git-server-over-http.txt[setup-git-server-over-http]
+link:howto/setup-git-server-over-http.html[setup-git-server-over-http]
for a slightly more sophisticated setup using WebDAV which also
allows pushing over HTTP.)
You can save space and make Git faster by moving these loose objects in
to a "pack file", which stores a group of objects in an efficient
compressed format; the details of how pack files are formatted can be
-found in link:technical/pack-format.txt[technical/pack-format.txt].
+found in link:technical/pack-format.html[pack format].
To put the loose objects into a pack, just run git repack:
$ git prune
------------------------------------------------
-and they'll be gone. But you should only run `git prune` on a quiescent
+and they'll be gone. (You should only run `git prune` on a quiescent
repository--it's kind of like doing a filesystem fsck recovery: you
don't want to do that while the filesystem is mounted.
-
-(The same is true of `git fsck` itself, btw, but since
-`git fsck` never actually *changes* the repository, it just reports
-on what it found, `git fsck` itself is never 'dangerous' to run.
-Running it while somebody is actually changing the repository can cause
-confusing and scary messages, but it won't actually do anything bad. In
-contrast, running `git prune` while somebody is actively changing the
-repository is a *BAD* idea).
+`git prune` is designed not to cause any harm in such cases of concurrent
+accesses to a repository but you might receive confusing or scary messages.)
[[recovering-from-repository-corruption]]
Recovering from repository corruption
result to the file pointed at by `.git/HEAD`, so that we can always see
what the last committed state was.
-Here is an ASCII art by Jon Loeliger that illustrates how
-various pieces fit together.
+Here is a picture that illustrates how various pieces fit together:
------------
Merging multiple trees
----------------------
-Git helps you do a three-way merge, which you can expand to n-way by
-repeating the merge procedure arbitrary times until you finally
-"commit" the state. The normal situation is that you'd only do one
-three-way merge (two parents), and commit it, but if you like to, you
-can do multiple parents in one go.
+Git can help you perform a three-way merge, which can in turn be
+used for a many-way merge by repeating the merge procedure several
+times. The usual situation is that you only do one three-way merge
+(reconciling two lines of history) and commit the result, but if
+you like to, you can merge several branches in one go.
-To do a three-way merge, you need the two sets of "commit" objects
-that you want to merge, use those to find the closest common parent (a
-third "commit" object), and then use those commit objects to find the
-state of the directory ("tree" object) at these points.
+To perform a three-way merge, you start with the two commits you
+want to merge, find their closest common parent (a third commit),
+and compare the trees corresponding to these three commits.
-To get the "base" for the merge, you first look up the common parent
-of two commits with
+To get the "base" for the merge, look up the common parent of two
+commits:
-------------------------------------------------
$ git merge-base <commit1> <commit2>
-------------------------------------------------
-which will return you the commit they are both based on. You should
-now look up the "tree" objects of those commits, which you can easily
-do with (for example)
+This prints the name of a commit they are both based on. You should
+now look up the tree objects of those commits, which you can easily
+do with
-------------------------------------------------
$ git cat-file commit <commitname> | head -1
that is used to name the object is the hash of the original data
plus this header, so `sha1sum` 'file' does not match the object name
for 'file'.
-(Historical note: in the dawn of the age of Git the hash
-was the SHA-1 of the 'compressed' object.)
As a result, the general consistency of an object can always be tested
independently of the contents or the type of the object: all objects can