# gitglossary

## NAME



           gitglossary - A Git Glossary
    


## SYNOPSIS



           *
    


## DESCRIPTION



           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.
    
           branch
               A "branch" is a 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 graph concept, representations and usage
               A synonym for the DAG structure formed by the commits in the
               object database, referenced by branch tips, using their chain
               of linked commits. This structure is the definitive commit
               graph. The graph can be represented in other ways, e.g. the
               "commit-graph" file.
    
           commit-graph file
               The "commit-graph" (normally hyphenated) file is a
               supplemental representation of the commit graph which
               accelerates commit graph walks. The "commit-graph" file is
               stored either in the .git/objects/info directory or in the
               info directory of an alternate object database.
    
           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.
    
           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.
    
           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.
    
           dereference
               Referring to a symbolic ref: the action of accessing the
               reference pointed at by a symbolic ref. Recursive
               dereferencing involves repeating the aforementioned process on
               the resulting ref until a non-symbolic reference is found.
    
               Referring to a tag object: the action of accessing the object
               a tag points at. Tags are recursively dereferenced by
               repeating the operation on the result object until the result
               has either a specified object type (where applicable) or any
               non-"tag" object type. A synonym for "recursive dereference"
               in the context of tags is "peel".
    
               Referring to a commit object: the action of accessing the
               commit’s tree object. Commits cannot be dereferenced
               recursively.
    
               Unless otherwise specified, "dereferencing" as it used in the
               context of Git commands or protocols is implicitly recursive.
    
           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.
    
           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.
    
           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 a case,
               you do not make a new merge commit but instead just update
               your branch to point at the same revision as the branch you
               are merging. 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).
    
           gitfile
               A plain file **.git** at the root of a working tree that points at
               the directory that is the real repository. For proper use see
               git-worktree(1) or git-submodule(1). For syntax see
               gitrepository-layout(5).
    
           grafts
               Grafts enable 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.
    
           hash
               In Git’s context, synonym for 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
               SHA-1 of its contents. Consequently, an object cannot 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 (oid)
               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.
    
           octopus
               To merge more than two branches.
    
           orphan
               The act of getting on a branch that does not exist yet (i.e.,
               an unborn branch). After such an operation, the commit first
               created becomes a commit without a parent, starting a new
               history.
    
           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-tracking branches named
               origin/name-of-upstream-branch, which you can see using **git**
               **branch -r**.
    
           overlay
               Only update and add files to the working directory, but don’t
               delete them, similar to how _cp -R_ would update the contents in
               the destination directory. This is the default mode in a
               checkout when checking out files from the index or a tree-ish.
               In contrast, no-overlay mode also deletes tracked files not
               present in the source, similar to _rsync --delete_.
    
           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 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 working tree. 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
                   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.
    
               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.
    
               top
                   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.
    
               literal
                   Wildcards in the pattern such as ***** or ? are treated as
                   literal characters.
    
               icase
                   Case insensitive match.
    
               glob
                   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. "****/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.
    
               attr
                   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.
    
                       Note that when matching against a tree object,
                       attributes are still obtained from working tree, not
                       from the given tree object.
    
               exclude
                   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.
    
           parent
               A commit object contains a (possibly empty) list of the
               logical predecessor(s) in the line of development, i.e. its
               parents.
    
           peel
               The action of recursively dereferencing a tag object.
    
           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.
    
           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.
    
           pseudoref
               A ref that has different semantics than normal refs. These
               refs can be read via normal Git commands, but cannot be
               written to by commands like git-update-ref(1).
    
               The following pseudorefs are known to Git:
    
               •   **FETCH_HEAD** is written by git-fetch(1) or git-pull(1). It
                   may refer to multiple object IDs. Each object ID is
                   annotated with metadata indicating where it was fetched
                   from and its fetch status.
    
               •   **MERGE_HEAD** is written by git-merge(1) when resolving merge
                   conflicts. It contains all commit IDs which are being
                   merged.
    
           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 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.
    
           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.
    
           reachability bitmaps
               Reachability bitmaps store information about the reachability
               of a selected set of commits in a packfile, or a multi-pack
               index (MIDX), to speed up object search. The bitmaps are
               stored in a ".bitmap" file. A repository may have at most one
               bitmap file in use. The bitmap file may belong to either one
               pack, or the repository’s multi-pack index (if it exists).
    
           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 name 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. Ref names must either start
               with **refs/** or be located in the root of the hierarchy. For the
               latter, their name must follow these rules:
    
               •   The name consists of only upper-case characters or
                   underscores.
    
               •   The name ends with "**_HEAD** " or is equal to "**HEAD** ".
    
                   There are some irregular refs in the root of the hierarchy
                   that do not match these rules. The following list is
                   exhaustive and shall not be extended in the future:
    
               •   **AUTO_MERGE**
    
               •   **BISECT_EXPECTED_REV**
    
               •   **NOTES_MERGE_PARTIAL**
    
               •   **NOTES_MERGE_REF**
    
               •   **MERGE_AUTOSTASH**
    
                   Different subhierarchies are used for different purposes.
                   For example, the **refs/heads/** hierarchy is used to
                   represent local branches whereas the **refs/tags/** hierarchy
                   is used to represent local tags..
    
           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. See git-fetch(1) or
               git-push(1) for details.
    
           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.
    
           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
               Synonym for commit (the noun).
    
           rewind
               To throw away part of the development, i.e. to assign the head
               to an earlier revision.
    
           SCM
               Source code management (tool).
    
           SHA-1
               "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.
    
           submodule
               A repository that holds the history of a separate project
               inside another repository (the latter of which is called
               superproject).
    
           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.
    
           symref
               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.
    
           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.
    
           trailer
               Key-value metadata. Trailers are optionally found at the end
               of a commit message. Might be called "footers" or "tags" in
               other communities. See git-interpret-trailers(1).
    
           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 (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.
    
           unborn
               The HEAD can point at a branch that does not yet exist and
               that does not have any commit on it yet, and such a branch is
               called an unborn branch. The most typical way users encounter
               an unborn branch is by creating a repository anew without
               cloning from elsewhere. The HEAD would point at the _main_ (or
               _master_ , depending on your configuration) branch that is yet to
               be born. Also some operations can get you on an unborn branch
               with their orphan option.
    
           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.
    
           worktree
               A repository can have zero (i.e. bare repository) or one or
               more worktrees attached to it. One "worktree" consists of a
               "working tree" and repository metadata, most of which are
               shared among other worktrees of a single repository, and some
               of which are maintained separately per worktree (e.g. the
               index, HEAD and pseudorefs like MERGE_HEAD, per-worktree refs
               and per-worktree configuration file).
    


## GIT



           Part of the git(1) suite
    


## NOTES



            1. The Git User’s Manual
               file:///home/mtk/share/doc/git-doc/user-manual.html
    


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