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GITGLOSSARY(7) | Git Manual | GITGLOSSARY(7) |
NAME¶
gitglossary - A GIT GlossarySYNOPSIS¶
*DESCRIPTION¶
alternate object databaseVia the alternates mechanism, a repository can
inherit part of its object database from another object database, which is
called "alternate".
bare repository
A bare repository is normally an appropriately
named directory with a .git suffix that does not have a locally checked-out
copy of any of the files under revision control. That is, all of the git
administrative and control files that would normally be present in the hidden
.git sub-directory are directly present in the repository.git directory
instead, and no other files are present and checked out. Usually publishers of
public repositories make bare repositories available.
blob object
Untyped object, e.g. the contents of a
file.
branch
A "branch" is an active line of
development. The most recent commit 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
repository can track an arbitrary number of branches, but your working tree is
associated with just one of them (the "current" or "checked
out" branch), and HEAD points to that branch.
cache
Obsolete for: index.
chain
A list of objects, where each object in the
list contains a reference to its successor (for example, the successor of a
commit could be one of its parents).
changeset
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.
checkout
The action of updating all or part of the
working tree with a tree object or blob from the object database, and updating
the index and HEAD if the whole working tree has been pointed at a new
branch.
cherry-picking
In SCM 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 commit and to record it based on the tip
of the current branch as a new commit.
clean
A working tree is clean, if it corresponds to
the revision referenced by the current head. Also see "dirty".
commit
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 commit object.
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 index and advancing HEAD to point at the new commit.
commit object
An object which contains the information about
a particular revision, such as parents, committer, author, date and the tree
object which corresponds to the top directory of the stored revision.
core git
Fundamental data structures and utilities of
git. Exposes only limited source code management tools.
DAG
Directed acyclic graph. The commit objects
form a directed acyclic graph, because they have parents (directed), and the
graph of commit objects is acyclic (there is no chain which begins and ends
with the same object).
dangling object
An unreachable object which is not reachable
even from other unreachable objects; a dangling object has no references to it
from any reference or object in the repository.
detached HEAD
Normally the HEAD stores the name of a branch.
However, git also allows you to check out an arbitrary commit that isn’t
necessarily the tip of any particular branch. In this case HEAD is said to be
"detached".
dircache
You are waaaaay behind. See
index.
directory
The list you get with "ls" :-)
dirty
A working tree is said to be "dirty"
if it contains modifications which have not been committed to the current
branch.
ent
Favorite synonym to "tree-ish" by
some total geeks. See http://en.wikipedia.org/wiki/Ent_(Middle-earth) for an
in-depth explanation. Avoid this term, not to confuse people.
evil merge
An evil merge is a merge that introduces
changes that do not appear in any parent.
fast-forward
A fast-forward is a special type of merge
where you have a revision 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 merge commit but instead just update to his revision.
This will happen frequently on a remote-tracking branch of a remote
repository.
fetch
Fetching a branch means to get the
branch’s head ref from a remote repository, to find out which objects
are missing from the local object database, and to get them, too. See also
git-fetch(1).
file system
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.
git archive
Synonym for repository (for arch
people).
grafts
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 parents a commit has
is different from what was recorded when the commit was created. Configured
via the .git/info/grafts file.
hash
In git’s context, synonym to object
name.
head
A named reference to the commit at the tip of
a branch. Heads are stored in a file in $GIT_DIR/refs/heads/ directory, except
when using packed refs. (See git-pack-refs(1).)
HEAD
The current branch. In more detail: Your
working tree is normally derived from the state of the tree referred to by
HEAD. HEAD is a reference to one of the heads in your repository, except when
using a detached HEAD, in which case it directly references an arbitrary
commit.
head ref
A synonym for head.
hook
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 $GIT_DIR/hooks/
directory, and are enabled by simply removing the .sample suffix from the
filename. In earlier versions of git you had to make them executable.
index
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 merging.
index entry
The information regarding a particular file,
stored in the index. An index entry can be unmerged, if a merge was started,
but not yet finished (i.e. if the index contains multiple versions of that
file).
master
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.
merge
As a verb: To bring the contents of another
branch (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 fetching 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 commit representing the result of the merge, and having as
parents the tips of the merged branches. This commit is referred to as a
"merge commit", or sometimes just a "merge".
object
The unit of storage in git. It is uniquely
identified by the SHA1 of its contents. Consequently, an object can not be
changed.
object database
Stores a set of "objects", and an
individual object is identified by its object name. The objects usually live
in $GIT_DIR/objects/.
object identifier
Synonym for object name.
object name
The unique identifier of an object. The hash
of the object’s contents using the Secure Hash Algorithm 1 and usually
represented by the 40 character hexadecimal encoding of the hash of the
object.
object type
One of the identifiers "commit",
"tree", "tag" or "blob" describing the type of
an object.
octopus
To merge more than two branches. Also denotes
an intelligent predator.
origin
The default upstream repository. Most projects
have at least one upstream project which they track. By default origin
is used for that purpose. New upstream updates will be fetched into remote
remote-tracking branches named origin/name-of-upstream-branch, which you can
see using git branch -r.
pack
A set of objects which have been compressed
into one file (to save space or to transmit them efficiently).
pack index
The list of identifiers, and other
information, of the objects in a pack, to assist in efficiently accessing the
contents of a pack.
pathspec
Pattern used to specify paths.
Pathspecs are used on the command line of "git ls-files", "git
ls-tree", "git add", "git grep", "git
diff", "git checkout", and many other commands to limit the
scope of operations to some subset of the tree or worktree. See the
documentation of each command for whether paths are relative to the current
directory or toplevel. The pathspec syntax is as follows:
A pathspec that begins with a colon : has special meaning. In the short form,
the leading colon : is followed by zero or more "magic signature"
letters (which optionally is terminated by another colon :), and the remainder
is the pattern to match against the path. The optional colon that terminates
the "magic signature" can be omitted if the pattern begins with a
character that cannot be a "magic signature" and is not a colon.
In the long form, the leading colon : is followed by a open parenthesis (, a
comma-separated list of zero or more "magic words", and a close
parentheses ), and the remainder is the pattern to match against the path.
The "magic signature" consists of an ASCII symbol that is not
alphanumeric.
top /
Currently only the slash / is recognized as the "magic signature", but
it is envisioned that we will support more types of magic in later versions of
git.
A pathspec with only a colon means "there is no pathspec". This form
should not be combined with other pathspec.
parent
•any path matches itself
•the pathspec up to the last slash
represents a directory prefix. The scope of that pathspec is limited to that
subtree.
•the rest of the pathspec is a pattern
for the remainder of the pathname. Paths relative to the directory prefix will
be matched against that pattern using fnmatch(3); in particular, * and
? can match directory separators.
For example, Documentation/*.jpg will match all .jpg files in the Documentation
subtree, including Documentation/chapter_1/figure_1.jpg.
The magic word top (mnemonic: /) makes the
pattern match from the root of the working tree, even when you are running the
command from inside a subdirectory.
A commit object contains a (possibly empty)
list of the logical predecessor(s) in the line of development, i.e. its
parents.
pickaxe
The term pickaxe refers to an option to the
diffcore routines that help select changes that add or delete a given text
string. With the --pickaxe-all option, it can be used to view the full
changeset that introduced or removed, say, a particular line of text. See
git-diff(1).
plumbing
Cute name for core git.
porcelain
Cute name for programs and program suites
depending on core git, presenting a high level access to core git. Porcelains
expose more of a SCM interface than the plumbing.
pull
Pulling a branch means to fetch it and merge
it. See also git-pull(1).
push
Pushing a branch means to get the
branch’s head ref 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 reachable 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 head is not an ancestor to the local head, the
push fails.
reachable
All of the ancestors of a given commit are
said to be "reachable" from that commit. More generally, one object
is reachable from another if we can reach the one from the other by a chain
that follows tags to whatever they tag, commits to their parents or trees, and
trees to the trees or blobs that they contain.
rebase
To reapply a series of changes from a branch
to a different base, and reset the head of that branch to the result.
ref
A 40-byte hex representation of a SHA1 or a
name that denotes a particular object. They may be stored in a file under
$GIT_DIR/refs/ directory, or in the $GIT_DIR/packed-refs file.
reflog
A reflog shows the local "history"
of a ref. In other words, it can tell you what the 3rd last revision in
this repository was, and what was the current state in this
repository, yesterday 9:14pm. See git-reflog(1) for details.
refspec
A "refspec" is used by fetch and
push to describe the mapping between remote ref 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 branch head
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 git-push(1).
remote-tracking branch
A regular git branch 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 ref in a Pull:
refspec.
repository
A collection of refs together with an object
database containing all objects which are reachable from the refs, possibly
accompanied by meta data from one or more porcelains. A repository can share
an object database with other repositories via alternates mechanism.
resolve
The action of fixing up manually what a failed
automatic merge left behind.
revision
A particular state of files and directories
which was stored in the object database. It is referenced by a commit
object.
rewind
To throw away part of the development, i.e. to
assign the head to an earlier revision.
SCM
Source code management (tool).
SHA1
Synonym for object name.
shallow repository
A shallow repository has an incomplete history
some of whose commits have parents 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 --depth option to git-clone(1), and its history
can be later deepened with git-fetch(1).
symref
Symbolic reference: instead of containing the
SHA1 id itself, it is of the format ref: refs/some/thing and when
referenced, it recursively dereferences to this reference. HEAD is a
prime example of a symref. Symbolic references are manipulated with the
git-symbolic-ref(1) command.
tag
A ref under refs/tags/ namespace that points
to an object of an arbitrary type (typically a tag points to either a tag or a
commit object). In contrast to a head, a tag is not updated by the commit
command. A git tag has nothing to do with a Lisp tag (which would be called an
object type in git’s context). A tag is most typically used to mark a
particular point in the commit ancestry chain.
tag object
An object containing a ref 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".
topic branch
A regular git branch 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.
tree
Either a working tree, or a tree object
together with the dependent blob and tree objects (i.e. a stored
representation of a working tree).
tree object
An object containing a list of file names and
modes along with refs to the associated blob and/or tree objects. A tree is
equivalent to a directory.
tree-ish
A ref pointing to either a commit object, a
tree object, or a tag object pointing to a tag or commit or tree object.
unmerged index
An index which contains unmerged index
entries.
unreachable object
An object which is not reachable from a
branch, tag, or any other reference.
upstream branch
The default branch 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 A is origin/B sometimes we say "
A is tracking origin/B".
working tree
The tree of actual checked out files. The
working tree normally contains the contents of the HEAD commit’s tree,
plus any local changes that you have made but not yet committed.
SEE ALSO¶
gittutorial(7), gittutorial-2(7), gitcvs-migration(7), Everyday git[1], The Git User’s Manual[2]GIT¶
Part of the git(1) suite.NOTES¶
- 1.
- Everyday git
- 2.
- The Git User’s Manual
03/19/2016 | Git 1.7.10.4 |