Via the alternates mechanism, a
can inherit part of its
from another object database, which is called "alternate".
A bare repository is normally an appropriately named
suffix that does not have a locally checked-out copy of any of the files under revision control. That is, all of the
administrative and control files that would normally be present in the hidden
sub-directory are directly present in the
directory instead, and no other files are present and checked out. Usually publishers of public repositories make bare repositories available.
object, e.g. the contents of a file.
A "branch" is an active line of development. The most recent
on a branch is referred to as the tip of that branch. The tip of the branch is referenced by a branch
head, which moves forward as additional development is done on the branch. A single git
can track an arbitrary number of branches, but your
is associated with just one of them (the "current" or "checked out" branch), and
points to that branch.
A list of objects, where each
in the list contains a reference to its successor (for example, the successor of a
could be one of its
BitKeeper/cvsps speak for "commit". Since git does not store changes, but states, it really does not make sense to use the term "changesets" with git.
The action of updating all or part of the
object database, and updating the
if the whole working tree has been pointed at a new
jargon, "cherry pick" means to choose a subset of changes out of a series of changes (typically commits) and record them as a new series of changes on top of a different codebase. In GIT, this is performed by the "git cherry-pick" command to extract the change introduced by an existing
and to record it based on the tip of the current
as a new commit.
is clean, if it corresponds to the
referenced by the current
head. Also see "dirty".
As a noun: A single point in the git history; the entire history of a project is represented as a set of interrelated commits. The word "commit" is often used by git in the same places other revision control systems use the words "revision" or "version". Also used as a short hand for
As a verb: The action of storing a new snapshot of the project's state in the git history, by creating a new commit representing the current state of the
to point at the new commit.
which contains the information about a particular
revision, such as
parents, committer, author, date and the
which corresponds to the top
of the stored revision.
Fundamental data structures and utilities of git. Exposes only limited source code management tools.
Directed acyclic graph. The
form a directed acyclic graph, because they have parents (directed), and the graph of commit objects is acyclic (there is no
which begins and ends with the same
which is not
even from other unreachable objects; a dangling object has no references to it from any reference or
stores the name of a
branch. However, git also allows you to
that isn't necessarily the tip of any particular branch. In this case HEAD is said to be "detached".
The list you get with "ls" :-)
is said to be "dirty" if it contains modifications which have not been
to the current
An evil merge is a
that introduces changes that do not appear in any
A fast-forward is a special type of
where you have a
and you are "merging" another
branch's changes that happen to be a descendant of what you have. In such these cases, you do not make a new
but instead just update to his revision. This will happen frequently on a
of a remote
means to get the branch's
from a remote
repository, to find out which objects are missing from the local
object database, and to get them, too. See also
Linus Torvalds originally designed git to be a user space file system, i.e. the infrastructure to hold files and directories. That ensured the efficiency and speed of git.
(for arch people).
Grafts enables two otherwise different lines of development to be joined together by recording fake ancestry information for commits. This way you can make git pretend the set of
has is different from what was recorded when the commit was created. Configured via the
In git's context, synonym to
at the tip of a
branch. Heads are stored in
$GIT_DIR/refs/heads/, except when using packed refs. (See
branch. In more detail: Your
is normally derived from the state of the tree referred to by HEAD. HEAD is a reference to one of the
in your repository, except when using a
detached HEAD, in which case it may reference an arbitrary commit.
A synonym for
During the normal execution of several git commands, call-outs are made to optional scripts that allow a developer to add functionality or checking. Typically, the hooks allow for a command to be pre-verified and potentially aborted, and allow for a post-notification after the operation is done. The hook scripts are found in the
directory, and are enabled by simply removing the
suffix from the filename. In earlier versions of git you had to make them executable.
A collection of files with stat information, whose contents are stored as objects. The index is a stored version of your
working tree. Truth be told, it can also contain a second, and even a third version of a working tree, which are used when
The information regarding a particular file, stored in the
index. An index entry can be unmerged, if a
was started, but not yet finished (i.e. if the index contains multiple versions of that file).
The default development
branch. Whenever you create a git
repository, a branch named "master" is created, and becomes the active branch. In most cases, this contains the local development, though that is purely by convention and is not required.
As a verb: To bring the contents of another
(possibly from an external
repository) into the current branch. In the case where the merged-in branch is from a different repository, this is done by first
the remote branch and then merging the result into the current branch. This combination of fetch and merge operations is called a
pull. Merging is performed by an automatic process that identifies changes made since the branches diverged, and then applies all those changes together. In cases where changes conflict, manual intervention may be required to complete the merge.
As a noun: unless it is a
fast-forward, a successful merge results in the creation of a new
representing the result of the merge, and having as
the tips of the merged
branches. This commit is referred to as a "merge commit", or sometimes just a "merge".
The unit of storage in git. It is uniquely identified by the
of its contents. Consequently, an object can not be changed.
Stores a set of "objects", and an individual
is identified by its
object name. The objects usually live in
The unique identifier of an
of the object's contents using the Secure Hash Algorithm 1 and usually represented by the 40 character hexadecimal encoding of the
of the object.
One of the identifiers "commit", "tree", "tag" or "blob" describing the type of an
more than two
branches. Also denotes an intelligent predator.
The default upstream
repository. Most projects have at least one upstream project which they track. By default
is used for that purpose. New upstream updates will be fetched into remote
named origin/name-of-upstream-branch, which you can see using
git branch -r.
A set of objects which have been compressed into one file (to save space or to transmit them efficiently).
The list of identifiers, and other information, of the objects in a
pack, to assist in efficiently accessing the contents of a pack.
contains a (possibly empty) list of the logical predecessor(s) in the line of development, i.e. its parents.
refers to an option to the diffcore routines that help select changes that add or delete a given text string. With the
option, it can be used to view the full
that introduced or removed, say, a particular line of text. See
Cute name for
Cute name for programs and program suites depending on
core git, presenting a high level access to core git. Porcelains expose more of a
interface than the
it. See also
means to get the branch's
from a remote
repository, find out if it is a direct ancestor to the branch's local head ref, and in that case, putting all objects, which are
from the local head ref, and which are missing from the remote repository, into the remote
object database, and updating the remote head ref. If the remote
is not an ancestor to the local head, the push fails.
All of the ancestors of a given
are said to be "reachable" from that commit. More generally, one
is reachable from another if we can reach the one from the other by a
to whatever they tag,
to their parents or trees, and
to the trees or
that they contain.
To reapply a series of changes from a
to a different base, and reset the
of that branch to the result.
A 40-byte hex representation of a
or a name that denotes a particular
object. These may be stored in
A reflog shows the local "history" of a ref. In other words, it can tell you what the 3rd last revision in
repository was, and what was the current state in
repository, yesterday 9:14pm. See
A "refspec" is used by
to describe the mapping between remote
and local ref. They are combined with a colon in the format <src>:<dst>, preceded by an optional plus sign, +. For example:
git fetch $URL refs/heads/master:refs/heads/origin
means "grab the master
from the $URL and store it as my origin branch head". And
git push $URL refs/heads/master:refs/heads/to-upstream
means "publish my master branch head as to-upstream branch at $URL". See also
A regular git
that is used to follow changes from another
repository. A remote-tracking branch should not contain direct modifications or have local commits made to it. A remote-tracking branch can usually be identified as the right-hand-side
in a Pull:
A collection of
together with an
containing all objects which are
from the refs, possibly accompanied by meta data from one or more
porcelains. A repository can share an object database with other repositories via
The action of fixing up manually what a failed automatic
A particular state of files and directories which was stored in the
object database. It is referenced by a
To throw away part of the development, i.e. to assign the
to an earlier
Source code management (tool).
has an incomplete history some of whose
cauterized away (in other words, git is told to pretend that these commits do not have the parents, even though they are recorded in the
commit object). This is sometimes useful when you are interested only in the recent history of a project even though the real history recorded in the upstream is much larger. A shallow repository is created by giving the
git-clone(1), and its history can be later deepened with
Symbolic reference: instead of containing the
id itself, it is of the format
and when referenced, it recursively dereferences to this reference.
is a prime example of a symref. Symbolic references are manipulated with the
pointing to a
commit object. In contrast to a
head, a tag is not changed by a
commit. Tags (not
tag objects) are stored in
$GIT_DIR/refs/tags/. A git tag has nothing to do with a Lisp tag (which would be called an
in git's context). A tag is most typically used to mark a particular point in the commit ancestry
pointing to another object, which can contain a message just like a
commit object. It can also contain a (PGP) signature, in which case it is called a "signed tag object".
A regular git
that is used by a developer to identify a conceptual line of development. Since branches are very easy and inexpensive, it is often desirable to have several small branches that each contain very well defined concepts or small incremental yet related changes.
working tree, or a
together with the dependent
and tree objects (i.e. a stored representation of a working tree).
containing a list of file names and modes along with refs to the associated blob and/or tree objects. A
is equivalent to a
pointing to either a
commit object, a
tree object, or a
pointing to a tag or commit or tree object.
which contains unmerged
which is not
tag, or any other reference.
that is merged into the branch in question (or the branch in question is rebased onto). It is configured via branch.<name>.remote and branch.<name>.merge. If the upstream branch of
sometimes we say "A
The tree of actual checked out files. The working tree normally contains the contents of the
commit's tree, plus any local changes that you have made but not yet committed.