The "master" branch that was created at the time you cloned is a copy
of the HEAD in the repository that you cloned from. That repository
may also have had other branches, though, and your local repository
-keeps branches which track each of those remote branches, which you
+keeps branches which track each of those remote branches, called
+remote-tracking branches, which you
can view using the "-r" option to linkgit:git-branch[1]:
------------------------------------------------
origin/todo
------------------------------------------------
-You cannot check out these remote-tracking branches, but you can
-examine them on a branch of your own, just as you would a tag:
+In this example, "origin" is called a remote repository, or "remote"
+for short. The branches of this repository are called "remote
+branches" from our point of view. The remote-tracking branches listed
+above were created based on the remote branches at clone time and will
+be updated by "git fetch" (hence "git pull") and "git push". See
+<<Updating-a-repository-With-git-fetch>> for details.
+
+You might want to build on one of these remote-tracking branches
+on a branch of your own, just as you would for a tag:
------------------------------------------------
$ git checkout -b my-todo-copy origin/todo
------------------------------------------------
+You can also check out "origin/todo" directly to examine it or
+write a one-off patch. See <<detached-head,detached head>>.
+
Note that the name "origin" is just the name that git uses by default
to refer to the repository that you cloned from.
For the complete list of paths which git checks for references, and
the order it uses to decide which to choose when there are multiple
references with the same shorthand name, see the "SPECIFYING
-REVISIONS" section of linkgit:git-rev-parse[1].
+REVISIONS" section of linkgit:gitrevisions[7].
[[Updating-a-repository-With-git-fetch]]
Updating a repository with git fetch
origin/master
-------------------------------------------------
-If you run "git fetch <remote>" later, the tracking branches for the
+If you run "git fetch <remote>" later, the remote-tracking branches for the
named <remote> will be updated.
If you examine the file .git/config, you will see that git has added
- HEAD: refers to the head of the current branch
There are many more; see the "SPECIFYING REVISIONS" section of the
-linkgit:git-rev-parse[1] man page for the complete list of ways to
+linkgit:gitrevisions[7] man page for the complete list of ways to
name revisions. Some examples:
-------------------------------------------------
$ gitk $( git show-ref --heads ) --not $( git show-ref --tags )
-------------------------------------------------
-(See linkgit:git-rev-parse[1] for explanations of commit-selecting
+(See linkgit:gitrevisions[7] for explanations of commit-selecting
syntax such as `--not`.)
[[making-a-release]]
and then he just cut-and-pastes the output commands after verifying that
they look OK.
-[[Finding-comments-With-given-Content]]
+[[Finding-commits-With-given-Content]]
Finding commits referencing a file with given content
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The linkgit:git-fsck[1] command runs a number of self-consistency checks
on the repository, and reports on any problems. This may take some
-time. The most common warning by far is about "dangling" objects:
+time.
-------------------------------------------------
$ git fsck
...
-------------------------------------------------
-Dangling objects are not a problem. At worst they may take up a little
-extra disk space. They can sometimes provide a last-resort method for
-recovering lost work--see <<dangling-objects>> for details.
+You will see informational messages on dangling objects. They are objects
+that still exist in the repository but are no longer referenced by any of
+your branches, and can (and will) be removed after a while with "gc".
+You can run `git fsck --no-dangling` to supress these messages, and still
+view real errors.
[[recovering-lost-changes]]
Recovering lost changes
The reflogs are kept by default for 30 days, after which they may be
pruned. See linkgit:git-reflog[1] and linkgit:git-gc[1] to learn
how to control this pruning, and see the "SPECIFYING REVISIONS"
-section of linkgit:git-rev-parse[1] for details.
+section of linkgit:gitrevisions[7] for details.
Note that the reflog history is very different from normal git history.
While normal history is shared by every repository that works on the
into your own work.
We have already seen <<Updating-a-repository-With-git-fetch,how to
-keep remote tracking branches up to date>> with linkgit:git-fetch[1],
+keep remote-tracking branches up to date>> with linkgit:git-fetch[1],
and how to merge two branches. So you can merge in changes from the
original repository's master branch with:
$ git pull origin master
-------------------------------------------------
-In fact, if you have "master" checked out, then by default "git pull"
-merges from the HEAD branch of the origin repository. So often you can
+In fact, if you have "master" checked out, then this branch has been
+configured by "git clone" to get changes from the HEAD branch of the
+origin repository. So often you can
accomplish the above with just a simple
-------------------------------------------------
$ git pull
-------------------------------------------------
-More generally, a branch that is created from a remote branch will pull
+This command will fetch changes from the remote branches to your
+remote-tracking branches `origin/*`, and merge the default branch into
+the current branch.
+
+More generally, a branch that is created from a remote-tracking branch
+will pull
by default from that branch. See the descriptions of the
branch.<name>.remote and branch.<name>.merge options in
linkgit:git-config[1], and the discussion of the `--track` option in
$ cd work
-------------------------------------------------
-Linus's tree will be stored in the remote branch named origin/master,
+Linus's tree will be stored in the remote-tracking branch named origin/master,
and can be updated using linkgit:git-fetch[1]; you can track other
public trees using linkgit:git-remote[1] to set up a "remote" and
linkgit:git-fetch[1] to keep them up-to-date; see
Now to apply some patches from the community. Think of a short
snappy name for a branch to hold this patch (or related group of
-patches), and create a new branch from the current tip of Linus's
-branch:
+patches), and create a new branch from a recent stable tag of
+Linus's branch. Picking a stable base for your branch will:
+1) help you: by avoiding inclusion of unrelated and perhaps lightly
+tested changes
+2) help future bug hunters that use "git bisect" to find problems
-------------------------------------------------
-$ git checkout -b speed-up-spinlocks origin
+$ git checkout -b speed-up-spinlocks v2.6.35
-------------------------------------------------
Now you apply the patch(es), run some tests, and commit the change(s). If
sequence of patches on top of "origin":
................................................
- o--o--o <-- origin
+ o--o--O <-- origin
\
- o--o--o <-- mywork
+ a--b--c <-- mywork
................................................
Some more interesting work has been done in the upstream project, and
may be lost, as we saw in the previous section.
[[remote-branch-configuration]]
-Configuring remote branches
----------------------------
+Configuring remote-tracking branches
+------------------------------------
We saw above that "origin" is just a shortcut to refer to the
repository that you originally cloned from. This information is
Assume the output looks like this:
------------------------------------------------
-$ git fsck --full
+$ git fsck --full --no-dangling
broken link from tree 2d9263c6d23595e7cb2a21e5ebbb53655278dff8
to blob 4b9458b3786228369c63936db65827de3cc06200
missing blob 4b9458b3786228369c63936db65827de3cc06200
------------------------------------------------
-(Typically there will be some "dangling object" messages too, but they
-aren't interesting.)
-
Now you know that blob 4b9458b3 is missing, and that the tree 2d9263c6
points to it. If you could find just one copy of that missing blob
object, possibly in some other repository, you could move it into
state at the time of the commit, and a list of parents:
-------------------------------------------------
-$ git commit-tree <tree> -p <parent> [-p <parent2> ..]
+$ git commit-tree <tree> -p <parent> [(-p <parent2>)...]
-------------------------------------------------
and then giving the reason for the commit on stdin (either through
negative numbers in case of different errors--and 0 on success.
- the variable `sha1` in the function signature of `get_sha1()` is `unsigned
- char \*`, but is actually expected to be a pointer to `unsigned
+ char {asterisk}`, but is actually expected to be a pointer to `unsigned
char[20]`. This variable will contain the 160-bit SHA-1 of the given
- commit. Note that whenever a SHA-1 is passed as `unsigned char \*`, it
+ commit. Note that whenever a SHA-1 is passed as `unsigned char {asterisk}`, it
is the binary representation, as opposed to the ASCII representation in
hex characters, which is passed as `char *`.