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       gitglossary - A Git Glossary


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

       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 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.

	   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 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
	   mergecommit 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.

	   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).

	   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

       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

	   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 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

	   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

	   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
	   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.

	   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.

	   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.

	   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:

	   o   any path matches itself

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

	   o   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

	       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

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

	       o   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".

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

	       o   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.

	       o   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:

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

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

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

	       o   "!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.

	       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

	   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

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

	   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

	   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=...

       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

       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

	   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 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.

	   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 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 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.

	   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).

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

       Part of the git(1) suite

	1. The Git User's Manual

Git 2.38.4			  05/16/2024			GITGLOSSARY(7)