GITGLOSSARY(7)                   Git Manual                   GITGLOSSARY(7)

NAME         top

       gitglossary - A Git Glossary

SYNOPSIS         top


DESCRIPTION         top

       alternate object database
           Via the alternates mechanism, a repository can inherit part of
           its object database from another object database, which is called
           an "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.

           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

           Obsolete for: index.

           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).

           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 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.

           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.

           A working tree is clean, if it corresponds to the revision
           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 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

       commit-ish (also committish)
           A commit object or an object that can be recursively dereferenced
           to a commit object. The following are all commit-ishes: a commit
           object, a tag object that points to a commit object, a tag object
           that points to a tag object that points to a commit object, etc.

       core Git
           Fundamental data structures and utilities of Git. Exposes only
           limited source code management tools.

           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, and commands that
           operate on the history HEAD represents operate on the history
           leading to the tip of the branch the HEAD points at. However, Git
           also allows you to check out an arbitrary commit that isn’t
           necessarily the tip of any particular branch. The HEAD in such a
           state is called "detached".

           Note that commands that operate on the history of the current
           branch (e.g.  git commit to build a new history on top of it)
           still work while the HEAD is detached. They update the HEAD to
           point at the tip of the updated history without affecting any
           branch. Commands that update or inquire information about the
           current branch (e.g.  git branch --set-upstream-to that sets what
           remote-tracking branch the current branch integrates with)
           obviously do not work, as there is no (real) current branch to
           ask about in this state.

           The list you get with "ls" :-)

           A working tree is said to be "dirty" if it contains modifications
           which have not been committed to the current branch.

       evil merge
           An evil merge is a merge that introduces changes that do not
           appear in any parent.

           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 a case, 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.

           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

       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).

           A plain file .git at the root of a working tree that points at
           the directory that is the real repository.

           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.

           Note that the grafts mechanism is outdated and can lead to
           problems transferring objects between repositories; see
           git-replace(1) for a more flexible and robust system to do the
           same thing.

           In Git’s context, synonym for object name.

           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).)

           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.

           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.

           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).

           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

           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".

           The unit of storage in Git. It is uniquely identified by the
           SHA-1 of its contents. Consequently, an object can not be

       object database
           Stores a set of "objects", and an individual object is identified
           by its object name. The objects usually live in

       object identifier
           Synonym for object name.

       object name
           The unique identifier of an object. The object name is usually
           represented by a 40 character hexadecimal string. Also
           colloquially called SHA-1.

       object type
           One of the identifiers "commit", "tree", "tag" or "blob"
           describing the type of an object.

           To merge more than two branches.

           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-tracking branches 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).

       pack index
           The list of identifiers, and other information, of the objects in
           a pack, to assist in efficiently accessing the contents of a

           Pattern used to limit paths in Git commands.

           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:

           ·   any path matches itself

           ·   the pathspec up to the last slash represents a directory
               prefix. The scope of that pathspec is limited to that

           ·   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

           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 "magic signature" consists of ASCII symbols
           that are neither alphanumeric, glob, regex special characters nor
           colon. The optional colon that terminates the "magic signature"
           can be omitted if the pattern begins with a character that does
           not belong to "magic signature" symbol set and is not a colon.

           In the long form, the leading colon : is followed by an 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.

           A pathspec with only a colon means "there is no pathspec". This
           form should not be combined with other pathspec.

               The magic word top (magic signature: /) makes the pattern
               match from the root of the working tree, even when you are
               running the command from inside a subdirectory.

               Wildcards in the pattern such as * or ?  are treated as
               literal characters.

               Case insensitive match.

               Git treats the pattern as a shell glob suitable for
               consumption by fnmatch(3) with the FNM_PATHNAME flag:
               wildcards in the pattern will not match a / in the pathname.
               For example, "Documentation/*.html" matches
               "Documentation/git.html" but not "Documentation/ppc/ppc.html"
               or "tools/perf/Documentation/perf.html".

               Two consecutive asterisks ("**") in patterns matched against
               full pathname may have special meaning:

               ·   A leading "**" followed by a slash means match in all
                   directories. For example, "**/foo" matches file or
                   directory "foo" anywhere, the same as pattern "foo".
                   "**/foo/bar" matches file or directory "bar" anywhere
                   that is directly under directory "foo".

               ·   A trailing "/**" matches everything inside. For example,
                   "abc/**" matches all files inside directory "abc",
                   relative to the location of the .gitignore file, with
                   infinite depth.

               ·   A slash followed by two consecutive asterisks then a
                   slash matches zero or more directories. For example,
                   "a/**/b" matches "a/b", "a/x/b", "a/x/y/b" and so on.

               ·   Other consecutive asterisks are considered invalid.

                   Glob magic is incompatible with literal magic.

               After attr: comes a space separated list of "attribute
               requirements", all of which must be met in order for the path
               to be considered a match; this is in addition to the usual
               non-magic pathspec pattern matching. See gitattributes(5).

               Each of the attribute requirements for the path takes one of
               these forms:

               ·   "ATTR" requires that the attribute ATTR be set.

               ·   "-ATTR" requires that the attribute ATTR be unset.

               ·   "ATTR=VALUE" requires that the attribute ATTR be set to
                   the string VALUE.

               ·   "!ATTR" requires that the attribute ATTR be unspecified.

               After a path matches any non-exclude pathspec, it will be run
               through all exclude pathspecs (magic signature: !  or its
               synonym ^). If it matches, the path is ignored. When there is
               no non-exclude pathspec, the exclusion is applied to the
               result set as if invoked without any pathspec.

           A commit object contains a (possibly empty) list of the logical
           predecessor(s) in the line of development, i.e. its parents.

           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).

           Cute name for core Git.

           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.

       per-worktree ref
           Refs that are per-worktree, rather than global. This is presently
           only HEAD and any refs that start with refs/bisect/, but might
           later include other unusual refs.

           Pseudorefs are a class of files under $GIT_DIR which behave like
           refs for the purposes of rev-parse, but which are treated
           specially by git. Pseudorefs both have names that are all-caps,
           and always start with a line consisting of a SHA-1 followed by
           whitespace. So, HEAD is not a pseudoref, because it is sometimes
           a symbolic ref. They might optionally contain some additional
           data.  MERGE_HEAD and CHERRY_PICK_HEAD are examples. Unlike
           per-worktree refs, these files cannot be symbolic refs, and never
           have reflogs. They also cannot be updated through the normal ref
           update machinery. Instead, they are updated by directly writing
           to the files. However, they can be read as if they were refs, so
           git rev-parse MERGE_HEAD will work.

           Pulling a branch means to fetch it and merge it. See also

           Pushing a branch means to get the branch’s head ref from a remote
           repository, find out if it is an 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.

           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.

           To reapply a series of changes from a branch to a different base,
           and reset the head of that branch to the result.

           A name that begins with refs/ (e.g.  refs/heads/master) that
           points to an object name or another ref (the latter is called a
           symbolic ref). For convenience, a ref can sometimes be
           abbreviated when used as an argument to a Git command; see
           gitrevisions(7) for details. Refs are stored in the repository.

           The ref namespace is hierarchical. Different subhierarchies are
           used for different purposes (e.g. the refs/heads/ hierarchy is
           used to represent local branches).

           There are a few special-purpose refs that do not begin with
           refs/. The most notable example is HEAD.

           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.

           A "refspec" is used by fetch and push to describe the mapping
           between remote ref and local ref.

       remote repository
           A repository which is used to track the same project but resides
           somewhere else. To communicate with remotes, see fetch or push.

       remote-tracking branch
           A ref that is used to follow changes from another repository. It
           typically looks like refs/remotes/foo/bar (indicating that it
           tracks a branch named bar in a remote named foo), and matches the
           right-hand-side of a configured fetch refspec. A remote-tracking
           branch should not contain direct modifications or have local
           commits made to it.

           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.

           The action of fixing up manually what a failed automatic merge
           left behind.

           Synonym for commit (the noun).

           To throw away part of the development, i.e. to assign the head to
           an earlier revision.

           Source code management (tool).

           "Secure Hash Algorithm 1"; a cryptographic hash function. In the
           context of Git used as a synonym for object name.

       shallow clone
           Mostly a synonym to shallow repository but the phrase makes it
           more explicit that it was created by running git clone
           --depth=...  command.

       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).

       stash entry
           An object used to temporarily store the contents of a dirty
           working directory and the index for future reuse.

           A repository that holds the history of a separate project inside
           another repository (the latter of which is called superproject).

           A repository that references repositories of other projects in
           its working tree as submodules. The superproject knows about the
           names of (but does not hold copies of) commit objects of the
           contained submodules.

           Symbolic reference: instead of containing the SHA-1 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.

           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

       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.

           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 (also treeish)
           A tree object or an object that can be recursively dereferenced
           to a tree object. Dereferencing a commit object yields the tree
           object corresponding to the revision's top directory. The
           following are all tree-ishes: a commit-ish, a tree object, a tag
           object that points to a tree object, a tag object that points to
           a tag object that points to a tree object, etc.

       unmerged index
           An index which contains unmerged index entries.

       unreachable object
           An object which is not reachable from a branch, tag, or any other

       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

       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         top

       gittutorial(7), gittutorial-2(7), gitcvs-migration(7),
       giteveryday(7), The Git User’s Manual[1]

GIT         top

       Part of the git(1) suite

NOTES         top

        1. The Git User’s Manual

COLOPHON         top

       This page is part of the git (Git distributed version control system)
       project.  Information about the project can be found at 
       ⟨⟩.  If you have a bug report for this manual page,
       see ⟨⟩.  This page was obtained from the
       project's upstream Git repository ⟨⟩ on
       2018-10-29.  (At that time, the date of the most recent commit that
       was found in the repository was 2018-10-26.)  If you discover any
       rendering problems in this HTML version of the page, or you believe
       there is a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to

Git           10/28/2018                   GITGLOSSARY(7)

Pages that refer to this page: git(1)git-add(1)git-grep(1)git-status(1)gitrepository-layout(5)gitcvs-migration(7)gitdiffcore(7)gittutorial-2(7)gittutorial(7)