1GITGLOSSARY(7) Git Manual GITGLOSSARY(7)
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6 gitglossary - A Git Glossary
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9 *
10
12 alternate object database
13 Via the alternates mechanism, a repository can inherit part of its
14 object database from another object database, which is called an
15 "alternate".
16 bare repository
18 A bare repository is normally an appropriately named directory with
19 a .git suffix that does not have a locally checked-out copy of any
20 of the files under revision control. That is, all of the Git
21 administrative and control files that would normally be present in
22 the hidden .git sub-directory are directly present in the
23 repository.git directory instead, and no other files are present
24 and checked out. Usually publishers of public repositories make
25 bare repositories available.
26 blob object
28 Untyped object, e.g. the contents of a file.
29 branch
31 A "branch" is an active line of development. The most recent commit
32 on a branch is referred to as the tip of that branch. The tip of
33 the branch is referenced by a branch head, which moves forward as
34 additional development is done on the branch. A single Git
35 repository can track an arbitrary number of branches, but your
36 working tree is associated with just one of them (the "current" or
37 "checked out" branch), and HEAD points to that branch.
38 cache
40 Obsolete for: index.
41 chain
43 A list of objects, where each object in the list contains a
44 reference to its successor (for example, the successor of a commit
45 could be one of its parents).
46 changeset
48 BitKeeper/cvsps speak for "commit". Since Git does not store
49 changes, but states, it really does not make sense to use the term
50 "changesets" with Git.
51 checkout
53 The action of updating all or part of the working tree with a tree
54 object or blob from the object database, and updating the index and
55 HEAD if the whole working tree has been pointed at a new branch.
56 cherry-picking
58 In SCM jargon, "cherry pick" means to choose a subset of changes
59 out of a series of changes (typically commits) and record them as a
60 new series of changes on top of a different codebase. In Git, this
61 is performed by the "git cherry-pick" command to extract the change
62 introduced by an existing commit and to record it based on the tip
63 of the current branch as a new commit.
64 clean
66 A working tree is clean, if it corresponds to the revision
67 referenced by the current head. Also see "dirty".
68 commit
70 As a noun: A single point in the Git history; the entire history of
71 a project is represented as a set of interrelated commits. The word
72 "commit" is often used by Git in the same places other revision
73 control systems use the words "revision" or "version". Also used as
74 a short hand for commit object.
75 As a verb: The action of storing a new snapshot of the project’s
77 state in the Git history, by creating a new commit representing the
78 current state of the index and advancing HEAD to point at the new
79 commit.
80 commit object
82 An object which contains the information about a particular
83 revision, such as parents, committer, author, date and the tree
84 object which corresponds to the top directory of the stored
85 revision.
86 commit-ish (also committish)
88 A commit object or an object that can be recursively dereferenced
89 to a commit object. The following are all commit-ishes: a commit
90 object, a tag object that points to a commit object, a tag object
91 that points to a tag object that points to a commit object, etc.
92 core Git
94 Fundamental data structures and utilities of Git. Exposes only
95 limited source code management tools.
96 DAG
98 Directed acyclic graph. The commit objects form a directed acyclic
99 graph, because they have parents (directed), and the graph of
100 commit objects is acyclic (there is no chain which begins and ends
101 with the same object).
102 dangling object
104 An unreachable object which is not reachable even from other
105 unreachable objects; a dangling object has no references to it from
106 any reference or object in the repository.
107 detached HEAD
109 Normally the HEAD stores the name of a branch, and commands that
110 operate on the history HEAD represents operate on the history
111 leading to the tip of the branch the HEAD points at. However, Git
112 also allows you to check out an arbitrary commit that isn’t
113 necessarily the tip of any particular branch. The HEAD in such a
114 state is called "detached".
115 Note that commands that operate on the history of the current
117 branch (e.g. git commit to build a new history on top of it) still
118 work while the HEAD is detached. They update the HEAD to point at
119 the tip of the updated history without affecting any branch.
120 Commands that update or inquire information about the current
121 branch (e.g. git branch --set-upstream-to that sets what
122 remote-tracking branch the current branch integrates with)
123 obviously do not work, as there is no (real) current branch to ask
124 about in this state.
125 directory
127 The list you get with "ls" :-)
128 dirty
130 A working tree is said to be "dirty" if it contains modifications
131 which have not been committed to the current branch.
132 evil merge
134 An evil merge is a merge that introduces changes that do not appear
135 in any parent.
136 fast-forward
138 A fast-forward is a special type of merge where you have a revision
139 and you are "merging" another branch's changes that happen to be a
140 descendant of what you have. In such a case, you do not make a new
141 merge commit but instead just update to his revision. This will
142 happen frequently on a remote-tracking branch of a remote
143 repository.
144 fetch
146 Fetching a branch means to get the branch’s head ref from a remote
147 repository, to find out which objects are missing from the local
148 object database, and to get them, too. See also git-fetch(1).
149 file system
151 Linus Torvalds originally designed Git to be a user space file
152 system, i.e. the infrastructure to hold files and directories. That
153 ensured the efficiency and speed of Git.
154 Git archive
156 Synonym for repository (for arch people).
157 gitfile
159 A plain file .git at the root of a working tree that points at the
160 directory that is the real repository.
161 grafts
163 Grafts enables two otherwise different lines of development to be
164 joined together by recording fake ancestry information for commits.
165 This way you can make Git pretend the set of parents a commit has
166 is different from what was recorded when the commit was created.
167 Configured via the .git/info/grafts file.
168 Note that the grafts mechanism is outdated and can lead to problems
170 transferring objects between repositories; see git-replace(1) for a
171 more flexible and robust system to do the same thing.
172 hash
174 In Git’s context, synonym for object name.
175 head
177 A named reference to the commit at the tip of a branch. Heads are
178 stored in a file in $GIT_DIR/refs/heads/ directory, except when
179 using packed refs. (See git-pack-refs(1).)
180 HEAD
182 The current branch. In more detail: Your working tree is normally
183 derived from the state of the tree referred to by HEAD. HEAD is a
184 reference to one of the heads in your repository, except when using
185 a detached HEAD, in which case it directly references an arbitrary
186 commit.
187 head ref
189 A synonym for head.
190 hook
192 During the normal execution of several Git commands, call-outs are
193 made to optional scripts that allow a developer to add
194 functionality or checking. Typically, the hooks allow for a command
195 to be pre-verified and potentially aborted, and allow for a
196 post-notification after the operation is done. The hook scripts are
197 found in the $GIT_DIR/hooks/ directory, and are enabled by simply
198 removing the .sample suffix from the filename. In earlier versions
199 of Git you had to make them executable.
200 index
202 A collection of files with stat information, whose contents are
203 stored as objects. The index is a stored version of your working
204 tree. Truth be told, it can also contain a second, and even a third
205 version of a working tree, which are used when merging.
206 index entry
208 The information regarding a particular file, stored in the index.
209 An index entry can be unmerged, if a merge was started, but not yet
210 finished (i.e. if the index contains multiple versions of that
211 file).
212 master
214 The default development branch. Whenever you create a Git
215 repository, a branch named "master" is created, and becomes the
216 active branch. In most cases, this contains the local development,
217 though that is purely by convention and is not required.
218 merge
220 As a verb: To bring the contents of another branch (possibly from
221 an external repository) into the current branch. In the case where
222 the merged-in branch is from a different repository, this is done
223 by first fetching the remote branch and then merging the result
224 into the current branch. This combination of fetch and merge
225 operations is called a pull. Merging is performed by an automatic
226 process that identifies changes made since the branches diverged,
227 and then applies all those changes together. In cases where changes
228 conflict, manual intervention may be required to complete the
229 merge.
230 As a noun: unless it is a fast-forward, a successful merge results
232 in the creation of a new commit representing the result of the
233 merge, and having as parents the tips of the merged branches. This
234 commit is referred to as a "merge commit", or sometimes just a
235 "merge".
236 object
238 The unit of storage in Git. It is uniquely identified by the SHA-1
239 of its contents. Consequently, an object can not be changed.
240 object database
242 Stores a set of "objects", and an individual object is identified
243 by its object name. The objects usually live in $GIT_DIR/objects/.
244 object identifier
246 Synonym for object name.
247 object name
249 The unique identifier of an object. The object name is usually
250 represented by a 40 character hexadecimal string. Also colloquially
251 called SHA-1.
252 object type
254 One of the identifiers "commit", "tree", "tag" or "blob" describing
255 the type of an object.
256 octopus
258 To merge more than two branches.
259 origin
261 The default upstream repository. Most projects have at least one
262 upstream project which they track. By default origin is used for
263 that purpose. New upstream updates will be fetched into
264 remote-tracking branches named origin/name-of-upstream-branch,
265 which you can see using git branch -r.
266 pack
268 A set of objects which have been compressed into one file (to save
269 space or to transmit them efficiently).
270 pack index
272 The list of identifiers, and other information, of the objects in a
273 pack, to assist in efficiently accessing the contents of a pack.
274 pathspec
276 Pattern used to limit paths in Git commands.
277 Pathspecs are used on the command line of "git ls-files", "git
279 ls-tree", "git add", "git grep", "git diff", "git checkout", and
280 many other commands to limit the scope of operations to some subset
281 of the tree or worktree. See the documentation of each command for
282 whether paths are relative to the current directory or toplevel.
283 The pathspec syntax is as follows:
284 · any path matches itself
286 · the pathspec up to the last slash represents a directory
288 prefix. The scope of that pathspec is limited to that subtree.
289 · the rest of the pathspec is a pattern for the remainder of the
291 pathname. Paths relative to the directory prefix will be
292 matched against that pattern using fnmatch(3); in particular, *
293 and ? can match directory separators.
294 For example, Documentation/*.jpg will match all .jpg files in the
296 Documentation subtree, including
297 Documentation/chapter_1/figure_1.jpg.
298 A pathspec that begins with a colon : has special meaning. In the
300 short form, the leading colon : is followed by zero or more "magic
301 signature" letters (which optionally is terminated by another colon
302 :), and the remainder is the pattern to match against the path. The
303 "magic signature" consists of ASCII symbols that are neither
304 alphanumeric, glob, regex special characters nor colon. The
305 optional colon that terminates the "magic signature" can be omitted
306 if the pattern begins with a character that does not belong to
307 "magic signature" symbol set and is not a colon.
308 In the long form, the leading colon : is followed by an open
310 parenthesis (, a comma-separated list of zero or more "magic
311 words", and a close parentheses ), and the remainder is the pattern
312 to match against the path.
313 A pathspec with only a colon means "there is no pathspec". This
315 form should not be combined with other pathspec.
316 top
318 The magic word top (magic signature: /) makes the pattern match
319 from the root of the working tree, even when you are running
320 the command from inside a subdirectory.
321 literal
323 Wildcards in the pattern such as * or ? are treated as literal
324 characters.
325 icase
327 Case insensitive match.
328 glob
330 Git treats the pattern as a shell glob suitable for consumption
331 by fnmatch(3) with the FNM_PATHNAME flag: wildcards in the
332 pattern will not match a / in the pathname. For example,
333 "Documentation/*.html" matches "Documentation/git.html" but not
334 "Documentation/ppc/ppc.html" or
335 "tools/perf/Documentation/perf.html".
336 Two consecutive asterisks ("**") in patterns matched against
338 full pathname may have special meaning:
339 · A leading "**" followed by a slash means match in all
341 directories. For example, "**/foo" matches file or
342 directory "foo" anywhere, the same as pattern "foo".
343 "**/foo/bar" matches file or directory "bar" anywhere that
344 is directly under directory "foo".
345 · A trailing "/**" matches everything inside. For example,
347 "abc/**" matches all files inside directory "abc", relative
348 to the location of the .gitignore file, with infinite
349 depth.
350 · A slash followed by two consecutive asterisks then a slash
352 matches zero or more directories. For example, "a/**/b"
353 matches "a/b", "a/x/b", "a/x/y/b" and so on.
354 · Other consecutive asterisks are considered invalid.
356 Glob magic is incompatible with literal magic.
358 attr
360 After attr: comes a space separated list of "attribute
361 requirements", all of which must be met in order for the path
362 to be considered a match; this is in addition to the usual
363 non-magic pathspec pattern matching. See gitattributes(5).
364 Each of the attribute requirements for the path takes one of
366 these forms:
367 · "ATTR" requires that the attribute ATTR be set.
369 · "-ATTR" requires that the attribute ATTR be unset.
371 · "ATTR=VALUE" requires that the attribute ATTR be set to the
373 string VALUE.
374 · "!ATTR" requires that the attribute ATTR be unspecified.
376 exclude
378 After a path matches any non-exclude pathspec, it will be run
379 through all exclude pathspecs (magic signature: ! or its
380 synonym ^). If it matches, the path is ignored. When there is
381 no non-exclude pathspec, the exclusion is applied to the result
382 set as if invoked without any pathspec.
383 parent
385 A commit object contains a (possibly empty) list of the logical
386 predecessor(s) in the line of development, i.e. its parents.
387 pickaxe
389 The term pickaxe refers to an option to the diffcore routines that
390 help select changes that add or delete a given text string. With
391 the --pickaxe-all option, it can be used to view the full changeset
392 that introduced or removed, say, a particular line of text. See
393 git-diff(1).
394 plumbing
396 Cute name for core Git.
397 porcelain
399 Cute name for programs and program suites depending on core Git,
400 presenting a high level access to core Git. Porcelains expose more
401 of a SCM interface than the plumbing.
402 per-worktree ref
404 Refs that are per-worktree, rather than global. This is presently
405 only HEAD and any refs that start with refs/bisect/, but might
406 later include other unusual refs.
407 pseudoref
409 Pseudorefs are a class of files under $GIT_DIR which behave like
410 refs for the purposes of rev-parse, but which are treated specially
411 by git. Pseudorefs both have names that are all-caps, and always
412 start with a line consisting of a SHA-1 followed by whitespace. So,
413 HEAD is not a pseudoref, because it is sometimes a symbolic ref.
414 They might optionally contain some additional data. MERGE_HEAD and
415 CHERRY_PICK_HEAD are examples. Unlike per-worktree refs, these
416 files cannot be symbolic refs, and never have reflogs. They also
417 cannot be updated through the normal ref update machinery. Instead,
418 they are updated by directly writing to the files. However, they
419 can be read as if they were refs, so git rev-parse MERGE_HEAD will
420 work.
421 pull
423 Pulling a branch means to fetch it and merge it. See also git-
424 pull(1).
425 push
427 Pushing a branch means to get the branch’s head ref from a remote
428 repository, find out if it is an ancestor to the branch’s local
429 head ref, and in that case, putting all objects, which are
430 reachable from the local head ref, and which are missing from the
431 remote repository, into the remote object database, and updating
432 the remote head ref. If the remote head is not an ancestor to the
433 local head, the push fails.
434 reachable
436 All of the ancestors of a given commit are said to be "reachable"
437 from that commit. More generally, one object is reachable from
438 another if we can reach the one from the other by a chain that
439 follows tags to whatever they tag, commits to their parents or
440 trees, and trees to the trees or blobs that they contain.
441 rebase
443 To reapply a series of changes from a branch to a different base,
444 and reset the head of that branch to the result.
445 ref
447 A name that begins with refs/ (e.g. refs/heads/master) that points
448 to an object name or another ref (the latter is called a symbolic
449 ref). For convenience, a ref can sometimes be abbreviated when used
450 as an argument to a Git command; see gitrevisions(7) for details.
451 Refs are stored in the repository.
452 The ref namespace is hierarchical. Different subhierarchies are
454 used for different purposes (e.g. the refs/heads/ hierarchy is used
455 to represent local branches).
456 There are a few special-purpose refs that do not begin with refs/.
458 The most notable example is HEAD.
459 reflog
461 A reflog shows the local "history" of a ref. In other words, it can
462 tell you what the 3rd last revision in this repository was, and
463 what was the current state in this repository, yesterday 9:14pm.
464 See git-reflog(1) for details.
465 refspec
467 A "refspec" is used by fetch and push to describe the mapping
468 between remote ref and local ref.
469 remote repository
471 A repository which is used to track the same project but resides
472 somewhere else. To communicate with remotes, see fetch or push.
473 remote-tracking branch
475 A ref that is used to follow changes from another repository. It
476 typically looks like refs/remotes/foo/bar (indicating that it
477 tracks a branch named bar in a remote named foo), and matches the
478 right-hand-side of a configured fetch refspec. A remote-tracking
479 branch should not contain direct modifications or have local
480 commits made to it.
481 repository
483 A collection of refs together with an object database containing
484 all objects which are reachable from the refs, possibly accompanied
485 by meta data from one or more porcelains. A repository can share an
486 object database with other repositories via alternates mechanism.
487 resolve
489 The action of fixing up manually what a failed automatic merge left
490 behind.
491 revision
493 Synonym for commit (the noun).
494 rewind
496 To throw away part of the development, i.e. to assign the head to
497 an earlier revision.
498 SCM
500 Source code management (tool).
501 SHA-1
503 "Secure Hash Algorithm 1"; a cryptographic hash function. In the
504 context of Git used as a synonym for object name.
505 shallow clone
507 Mostly a synonym to shallow repository but the phrase makes it more
508 explicit that it was created by running git clone --depth=...
509 command.
510 shallow repository
512 A shallow repository has an incomplete history some of whose
513 commits have parents cauterized away (in other words, Git is told
514 to pretend that these commits do not have the parents, even though
515 they are recorded in the commit object). This is sometimes useful
516 when you are interested only in the recent history of a project
517 even though the real history recorded in the upstream is much
518 larger. A shallow repository is created by giving the --depth
519 option to git-clone(1), and its history can be later deepened with
520 git-fetch(1).
521 stash entry
523 An object used to temporarily store the contents of a dirty working
524 directory and the index for future reuse.
525 submodule
527 A repository that holds the history of a separate project inside
528 another repository (the latter of which is called superproject).
529 superproject
531 A repository that references repositories of other projects in its
532 working tree as submodules. The superproject knows about the names
533 of (but does not hold copies of) commit objects of the contained
534 submodules.
535 symref
537 Symbolic reference: instead of containing the SHA-1 id itself, it
538 is of the format ref: refs/some/thing and when referenced, it
539 recursively dereferences to this reference. HEAD is a prime
540 example of a symref. Symbolic references are manipulated with the
541 git-symbolic-ref(1) command.
542 tag
544 A ref under refs/tags/ namespace that points to an object of an
545 arbitrary type (typically a tag points to either a tag or a commit
546 object). In contrast to a head, a tag is not updated by the commit
547 command. A Git tag has nothing to do with a Lisp tag (which would
548 be called an object type in Git’s context). A tag is most typically
549 used to mark a particular point in the commit ancestry chain.
550 tag object
552 An object containing a ref pointing to another object, which can
553 contain a message just like a commit object. It can also contain a
554 (PGP) signature, in which case it is called a "signed tag object".
555 topic branch
557 A regular Git branch that is used by a developer to identify a
558 conceptual line of development. Since branches are very easy and
559 inexpensive, it is often desirable to have several small branches
560 that each contain very well defined concepts or small incremental
561 yet related changes.
562 tree
564 Either a working tree, or a tree object together with the dependent
565 blob and tree objects (i.e. a stored representation of a working
566 tree).
567 tree object
569 An object containing a list of file names and modes along with refs
570 to the associated blob and/or tree objects. A tree is equivalent to
571 a directory.
572 tree-ish (also treeish)
574 A tree object or an object that can be recursively dereferenced to
575 a tree object. Dereferencing a commit object yields the tree object
576 corresponding to the revision's top directory. The following are
577 all tree-ishes: a commit-ish, a tree object, a tag object that
578 points to a tree object, a tag object that points to a tag object
579 that points to a tree object, etc.
580 unmerged index
582 An index which contains unmerged index entries.
583 unreachable object
585 An object which is not reachable from a branch, tag, or any other
586 reference.
587 upstream branch
589 The default branch that is merged into the branch in question (or
590 the branch in question is rebased onto). It is configured via
591 branch.<name>.remote and branch.<name>.merge. If the upstream
592 branch of A is origin/B sometimes we say "A is tracking origin/B".
593 working tree
595 The tree of actual checked out files. The working tree normally
596 contains the contents of the HEAD commit’s tree, plus any local
597 changes that you have made but not yet committed.
598
600 gittutorial(7), gittutorial-2(7), gitcvs-migration(7), giteveryday(7),
601 The Git User’s Manual[1]
602
604 Part of the git(1) suite
605
607 1. The Git User’s Manual
608 file:///usr/share/doc/git/user-manual.html
609Git 2.20.1 12/15/2018 GITGLOSSARY(7)