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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 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.

	   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
	   merge commit	but instead just update	to his revision. This will
	   happen frequently on	a remote-tracking branch of a remote

	   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 worktree. 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.

       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 2.28.0			  07/26/2020			GITGLOSSARY(7)


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