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1 [[def_alternate_object_database]]alternate object database::
2 Via the alternates mechanism, a <<def_repository,repository>>
3 can inherit part of its <<def_object_database,object database>>
4 from another object database, which is called an "alternate".
6 [[def_bare_repository]]bare repository::
7 A bare repository is normally an appropriately
8 named <<def_directory,directory>> with a `.git` suffix that does not
9 have a locally checked-out copy of any of the files under
10 revision control. That is, all of the Git
11 administrative and control files that would normally be present in the
12 hidden `.git` sub-directory are directly present in the
13 `repository.git` directory instead,
14 and no other files are present and checked out. Usually publishers of
15 public repositories make bare repositories available.
17 [[def_blob_object]]blob object::
18 Untyped <<def_object,object>>, e.g. the contents of a file.
20 [[def_branch]]branch::
21 A "branch" is a line of development. The most recent
22 <<def_commit,commit>> on a branch is referred to as the tip of
23 that branch. The tip of the branch is <<def_ref,referenced>> by a branch
24 <<def_head,head>>, which moves forward as additional development
25 is done on the branch. A single Git
26 <<def_repository,repository>> can track an arbitrary number of
27 branches, but your <<def_working_tree,working tree>> is
28 associated with just one of them (the "current" or "checked out"
29 branch), and <<def_HEAD,HEAD>> points to that branch.
31 [[def_cache]]cache::
32 Obsolete for: <<def_index,index>>.
34 [[def_chain]]chain::
35 A list of objects, where each <<def_object,object>> in the list contains
36 a reference to its successor (for example, the successor of a
37 <<def_commit,commit>> could be one of its <<def_parent,parents>>).
39 [[def_changeset]]changeset::
40 BitKeeper/cvsps speak for "<<def_commit,commit>>". Since Git does not
41 store changes, but states, it really does not make sense to use the term
42 "changesets" with Git.
44 [[def_checkout]]checkout::
45 The action of updating all or part of the
46 <<def_working_tree,working tree>> with a <<def_tree_object,tree object>>
47 or <<def_blob_object,blob>> from the
48 <<def_object_database,object database>>, and updating the
49 <<def_index,index>> and <<def_HEAD,HEAD>> if the whole working tree has
50 been pointed at a new <<def_branch,branch>>.
52 [[def_cherry-picking]]cherry-picking::
53 In <<def_SCM,SCM>> jargon, "cherry pick" means to choose a subset of
54 changes out of a series of changes (typically commits) and record them
55 as a new series of changes on top of a different codebase. In Git, this is
56 performed by the "git cherry-pick" command to extract the change introduced
57 by an existing <<def_commit,commit>> and to record it based on the tip
58 of the current <<def_branch,branch>> as a new commit.
60 [[def_clean]]clean::
61 A <<def_working_tree,working tree>> is clean, if it
62 corresponds to the <<def_revision,revision>> referenced by the current
63 <<def_head,head>>. Also see "<<def_dirty,dirty>>".
65 [[def_commit]]commit::
66 As a noun: A single point in the
67 Git history; the entire history of a project is represented as a
68 set of interrelated commits. The word "commit" is often
69 used by Git in the same places other revision control systems
70 use the words "revision" or "version". Also used as a short
71 hand for <<def_commit_object,commit object>>.
72 +
73 As a verb: The action of storing a new snapshot of the project's
74 state in the Git history, by creating a new commit representing the current
75 state of the <<def_index,index>> and advancing <<def_HEAD,HEAD>>
76 to point at the new commit.
78 [[def_commit_graph_general]]commit graph concept, representations and usage::
79 A synonym for the <<def_DAG,DAG>> structure formed by the commits
80 in the object database, <<def_ref,referenced>> by branch tips,
81 using their <<def_chain,chain>> of linked commits.
82 This structure is the definitive commit graph. The
83 graph can be represented in other ways, e.g. the
84 <<def_commit_graph_file,"commit-graph" file>>.
86 [[def_commit_graph_file]]commit-graph file::
87 The "commit-graph" (normally hyphenated) file is a supplemental
88 representation of the <<def_commit_graph_general,commit graph>>
89 which accelerates commit graph walks. The "commit-graph" file is
90 stored either in the .git/objects/info directory or in the info
91 directory of an alternate object database.
93 [[def_commit_object]]commit object::
94 An <<def_object,object>> which contains the information about a
95 particular <<def_revision,revision>>, such as <<def_parent,parents>>, committer,
96 author, date and the <<def_tree_object,tree object>> which corresponds
97 to the top <<def_directory,directory>> of the stored
98 revision.
100 [[def_commit-ish]]commit-ish (also committish)::
101 A <<def_commit_object,commit object>> or an <<def_object,object>> that
102 can be recursively <<def_dereference,dereferenced>> to a commit object.
103 The following are all commit-ishes:
104 a commit object,
105 a <<def_tag_object,tag object>> that points to a commit
106 object,
107 a tag object that points to a tag object that points to a
108 commit object,
109 etc.
111 [[def_core_git]]core Git::
112 Fundamental data structures and utilities of Git. Exposes only limited
113 source code management tools.
115 [[def_DAG]]DAG::
116 Directed acyclic graph. The <<def_commit_object,commit objects>> form a
117 directed acyclic graph, because they have parents (directed), and the
118 graph of commit objects is acyclic (there is no <<def_chain,chain>>
119 which begins and ends with the same <<def_object,object>>).
121 [[def_dangling_object]]dangling object::
122 An <<def_unreachable_object,unreachable object>> which is not
123 <<def_reachable,reachable>> even from other unreachable objects; a
124 dangling object has no references to it from any
125 reference or <<def_object,object>> in the <<def_repository,repository>>.
127 [[def_dereference]]dereference::
128 Referring to a <<def_symref,symbolic ref>>: the action of accessing the
129 <<def_ref,reference>> pointed at by a symbolic ref. Recursive
130 dereferencing involves repeating the aforementioned process on the
131 resulting ref until a non-symbolic reference is found.
132 +
133 Referring to a <<def_tag_object,tag object>>: the action of accessing the
134 <<def_object,object>> a tag points at. Tags are recursively dereferenced by
135 repeating the operation on the result object until the result has either a
136 specified <<def_object_type,object type>> (where applicable) or any non-"tag"
137 object type. A synonym for "recursive dereference" in the context of tags is
138 "<<def_peel,peel>>".
139 +
140 Referring to a <<def_commit_object,commit object>>: the action of accessing
141 the commit's tree object. Commits cannot be dereferenced recursively.
142 +
143 Unless otherwise specified, "dereferencing" as it used in the context of Git
144 commands or protocols is implicitly recursive.
146 [[def_detached_HEAD]]detached HEAD::
147 Normally the <<def_HEAD,HEAD>> stores the name of a
148 <<def_branch,branch>>, and commands that operate on the
149 history HEAD represents operate on the history leading to the
150 tip of the branch the HEAD points at. However, Git also
151 allows you to <<def_checkout,check out>> an arbitrary
152 <<def_commit,commit>> that isn't necessarily the tip of any
153 particular branch. The HEAD in such a state is called
154 "detached".
155 +
156 Note that commands that operate on the history of the current branch
157 (e.g. `git commit` to build a new history on top of it) still work
158 while the HEAD is detached. They update the HEAD to point at the tip
159 of the updated history without affecting any branch. Commands that
160 update or inquire information _about_ the current branch (e.g. `git
161 branch --set-upstream-to` that sets what remote-tracking branch the
162 current branch integrates with) obviously do not work, as there is no
163 (real) current branch to ask about in this state.
165 [[def_directory]]directory::
166 The list you get with "ls" :-)
168 [[def_dirty]]dirty::
169 A <<def_working_tree,working tree>> is said to be "dirty" if
170 it contains modifications which have not been <<def_commit,committed>> to the current
171 <<def_branch,branch>>.
173 [[def_evil_merge]]evil merge::
174 An evil merge is a <<def_merge,merge>> that introduces changes that
175 do not appear in any <<def_parent,parent>>.
177 [[def_fast_forward]]fast-forward::
178 A fast-forward is a special type of <<def_merge,merge>> where you have a
179 <<def_revision,revision>> and you are "merging" another
180 <<def_branch,branch>>'s changes that happen to be a descendant of what
181 you have. In such a case, you do not make a new <<def_merge,merge>>
182 <<def_commit,commit>> but instead just update your branch to point at the same
183 revision as the branch you are merging. This will happen frequently on a
184 <<def_remote_tracking_branch,remote-tracking branch>> of a remote
185 <<def_repository,repository>>.
187 [[def_fetch]]fetch::
188 Fetching a <<def_branch,branch>> means to get the
189 branch's <<def_head_ref,head ref>> from a remote
190 <<def_repository,repository>>, to find out which objects are
191 missing from the local <<def_object_database,object database>>,
192 and to get them, too. See also linkgit:git-fetch[1].
194 [[def_file_system]]file system::
195 Linus Torvalds originally designed Git to be a user space file system,
196 i.e. the infrastructure to hold files and directories. That ensured the
197 efficiency and speed of Git.
199 [[def_git_archive]]Git archive::
200 Synonym for <<def_repository,repository>> (for arch people).
202 [[def_gitfile]]gitfile::
203 A plain file `.git` at the root of a working tree that
204 points at the directory that is the real repository.
205 For proper use see linkgit:git-worktree[1] or linkgit:git-submodule[1].
206 For syntax see linkgit:gitrepository-layout[5].
208 [[def_grafts]]grafts::
209 Grafts enable two otherwise different lines of development to be joined
210 together by recording fake ancestry information for commits. This way
211 you can make Git pretend the set of <<def_parent,parents>> a <<def_commit,commit>> has
212 is different from what was recorded when the commit was
213 created. Configured via the `.git/info/grafts` file.
214 +
215 Note that the grafts mechanism is outdated and can lead to problems
216 transferring objects between repositories; see linkgit:git-replace[1]
217 for a more flexible and robust system to do the same thing.
219 [[def_hash]]hash::
220 In Git's context, synonym for <<def_object_name,object name>>.
222 [[def_head]]head::
223 A <<def_ref,named reference>> to the <<def_commit,commit>> at the tip of a
224 <<def_branch,branch>>. Heads are stored in a file in
225 `$GIT_DIR/refs/heads/` directory, except when using packed refs. (See
226 linkgit:git-pack-refs[1].)
228 [[def_HEAD]]HEAD::
229 The current <<def_branch,branch>>. In more detail: Your <<def_working_tree,
230 working tree>> is normally derived from the state of the tree
231 referred to by HEAD. HEAD is a reference to one of the
232 <<def_head,heads>> in your repository, except when using a
233 <<def_detached_HEAD,detached HEAD>>, in which case it directly
234 references an arbitrary commit.
236 [[def_head_ref]]head ref::
237 A synonym for <<def_head,head>>.
239 [[def_hook]]hook::
240 During the normal execution of several Git commands, call-outs are made
241 to optional scripts that allow a developer to add functionality or
242 checking. Typically, the hooks allow for a command to be pre-verified
243 and potentially aborted, and allow for a post-notification after the
244 operation is done. The hook scripts are found in the
245 `$GIT_DIR/hooks/` directory, and are enabled by simply
246 removing the `.sample` suffix from the filename. In earlier versions
247 of Git you had to make them executable.
249 [[def_index]]index::
250 A collection of files with stat information, whose contents are stored
251 as objects. The index is a stored version of your
252 <<def_working_tree,working tree>>. Truth be told, it can also contain a second, and even
253 a third version of a working tree, which are used
254 when <<def_merge,merging>>.
256 [[def_index_entry]]index entry::
257 The information regarding a particular file, stored in the
258 <<def_index,index>>. An index entry can be unmerged, if a
259 <<def_merge,merge>> was started, but not yet finished (i.e. if
260 the index contains multiple versions of that file).
262 [[def_master]]master::
263 The default development <<def_branch,branch>>. Whenever you
264 create a Git <<def_repository,repository>>, a branch named
265 "master" is created, and becomes the active branch. In most
266 cases, this contains the local development, though that is
267 purely by convention and is not required.
269 [[def_merge]]merge::
270 As a verb: To bring the contents of another
271 <<def_branch,branch>> (possibly from an external
272 <<def_repository,repository>>) into the current branch. In the
273 case where the merged-in branch is from a different repository,
274 this is done by first <<def_fetch,fetching>> the remote branch
275 and then merging the result into the current branch. This
276 combination of fetch and merge operations is called a
277 <<def_pull,pull>>. Merging is performed by an automatic process
278 that identifies changes made since the branches diverged, and
279 then applies all those changes together. In cases where changes
280 conflict, manual intervention may be required to complete the
281 merge.
282 +
283 As a noun: unless it is a <<def_fast_forward,fast-forward>>, a
284 successful merge results in the creation of a new <<def_commit,commit>>
285 representing the result of the merge, and having as
286 <<def_parent,parents>> the tips of the merged <<def_branch,branches>>.
287 This commit is referred to as a "merge commit", or sometimes just a
288 "merge".
290 [[def_object]]object::
291 The unit of storage in Git. It is uniquely identified by the
292 <<def_SHA1,SHA-1>> of its contents. Consequently, an
293 object cannot be changed.
295 [[def_object_database]]object database::
296 Stores a set of "objects", and an individual <<def_object,object>> is
297 identified by its <<def_object_name,object name>>. The objects usually
298 live in `$GIT_DIR/objects/`.
300 [[def_object_identifier]]object identifier (oid)::
301 Synonym for <<def_object_name,object name>>.
303 [[def_object_name]]object name::
304 The unique identifier of an <<def_object,object>>. The
305 object name is usually represented by a 40 character
306 hexadecimal string. Also colloquially called <<def_SHA1,SHA-1>>.
308 [[def_object_type]]object type::
309 One of the identifiers "<<def_commit_object,commit>>",
310 "<<def_tree_object,tree>>", "<<def_tag_object,tag>>" or
311 "<<def_blob_object,blob>>" describing the type of an
312 <<def_object,object>>.
314 [[def_octopus]]octopus::
315 To <<def_merge,merge>> more than two <<def_branch,branches>>.
317 [[def_orphan]]orphan::
318 The act of getting on a <<def_branch,branch>> that does not
319 exist yet (i.e., an <<def_unborn,unborn>> branch). After
320 such an operation, the commit first created becomes a commit
321 without a parent, starting a new history.
323 [[def_origin]]origin::
324 The default upstream <<def_repository,repository>>. Most projects have
325 at least one upstream project which they track. By default
326 'origin' is used for that purpose. New upstream updates
327 will be fetched into <<def_remote_tracking_branch,remote-tracking branches>> named
328 origin/name-of-upstream-branch, which you can see using
329 `git branch -r`.
331 [[def_overlay]]overlay::
332 Only update and add files to the working directory, but don't
333 delete them, similar to how 'cp -R' would update the contents
334 in the destination directory. This is the default mode in a
335 <<def_checkout,checkout>> when checking out files from the
336 <<def_index,index>> or a <<def_tree-ish,tree-ish>>. In
337 contrast, no-overlay mode also deletes tracked files not
338 present in the source, similar to 'rsync --delete'.
340 [[def_pack]]pack::
341 A set of objects which have been compressed into one file (to save space
342 or to transmit them efficiently).
344 [[def_pack_index]]pack index::
345 The list of identifiers, and other information, of the objects in a
346 <<def_pack,pack>>, to assist in efficiently accessing the contents of a
347 pack.
349 [[def_pathspec]]pathspec::
350 Pattern used to limit paths in Git commands.
351 +
352 Pathspecs are used on the command line of "git ls-files", "git
353 ls-tree", "git add", "git grep", "git diff", "git checkout",
354 and many other commands to
355 limit the scope of operations to some subset of the tree or
356 working tree. See the documentation of each command for whether
357 paths are relative to the current directory or toplevel. The
358 pathspec syntax is as follows:
359 +
360 --
362 * any path matches itself
363 * the pathspec up to the last slash represents a
364 directory prefix. The scope of that pathspec is
365 limited to that subtree.
366 * the rest of the pathspec is a pattern for the remainder
367 of the pathname. Paths relative to the directory
368 prefix will be matched against that pattern using fnmatch(3);
369 in particular, '*' and '?' _can_ match directory separators.
371 --
372 +
373 For example, Documentation/*.jpg will match all .jpg files
374 in the Documentation subtree,
375 including Documentation/chapter_1/figure_1.jpg.
376 +
377 A pathspec that begins with a colon `:` has special meaning. In the
378 short form, the leading colon `:` is followed by zero or more "magic
379 signature" letters (which optionally is terminated by another colon `:`),
380 and the remainder is the pattern to match against the path.
381 The "magic signature" consists of ASCII symbols that are neither
382 alphanumeric, glob, regex special characters nor colon.
383 The optional colon that terminates the "magic signature" can be
384 omitted if the pattern begins with a character that does not belong to
385 "magic signature" symbol set and is not a colon.
386 +
387 In the long form, the leading colon `:` is followed by an open
388 parenthesis `(`, a comma-separated list of zero or more "magic words",
389 and a close parentheses `)`, and the remainder is the pattern to match
390 against the path.
391 +
392 A pathspec with only a colon means "there is no pathspec". This form
393 should not be combined with other pathspec.
394 +
395 --
396 top;;
397 The magic word `top` (magic signature: `/`) makes the pattern
398 match from the root of the working tree, even when you are
399 running the command from inside a subdirectory.
401 literal;;
402 Wildcards in the pattern such as `*` or `?` are treated
403 as literal characters.
405 icase;;
406 Case insensitive match.
408 glob;;
409 Git treats the pattern as a shell glob suitable for
410 consumption by fnmatch(3) with the FNM_PATHNAME flag:
411 wildcards in the pattern will not match a / in the pathname.
412 For example, "Documentation/{asterisk}.html" matches
413 "Documentation/git.html" but not "Documentation/ppc/ppc.html"
414 or "tools/perf/Documentation/perf.html".
415 +
416 Two consecutive asterisks ("`**`") in patterns matched against
417 full pathname may have special meaning:
419 - A leading "`**`" followed by a slash means match in all
420 directories. For example, "`**/foo`" matches file or directory
421 "`foo`" anywhere, the same as pattern "`foo`". "`**/foo/bar`"
422 matches file or directory "`bar`" anywhere that is directly
423 under directory "`foo`".
425 - A trailing "`/**`" matches everything inside. For example,
426 "`abc/**`" matches all files inside directory "abc", relative
427 to the location of the `.gitignore` file, with infinite depth.
429 - A slash followed by two consecutive asterisks then a slash
430 matches zero or more directories. For example, "`a/**/b`"
431 matches "`a/b`", "`a/x/b`", "`a/x/y/b`" and so on.
433 - Other consecutive asterisks are considered invalid.
434 +
435 Glob magic is incompatible with literal magic.
437 attr;;
438 After `attr:` comes a space separated list of "attribute
439 requirements", all of which must be met in order for the
440 path to be considered a match; this is in addition to the
441 usual non-magic pathspec pattern matching.
442 See linkgit:gitattributes[5].
443 +
444 Each of the attribute requirements for the path takes one of
445 these forms:
447 - "`ATTR`" requires that the attribute `ATTR` be set.
449 - "`-ATTR`" requires that the attribute `ATTR` be unset.
451 - "`ATTR=VALUE`" requires that the attribute `ATTR` be
452 set to the string `VALUE`.
454 - "`!ATTR`" requires that the attribute `ATTR` be
455 unspecified.
456 +
457 Note that when matching against a tree object, attributes are still
458 obtained from working tree, not from the given tree object.
460 exclude;;
461 After a path matches any non-exclude pathspec, it will be run
462 through all exclude pathspecs (magic signature: `!` or its
463 synonym `^`). If it matches, the path is ignored. When there
464 is no non-exclude pathspec, the exclusion is applied to the
465 result set as if invoked without any pathspec.
466 --
468 [[def_parent]]parent::
469 A <<def_commit_object,commit object>> contains a (possibly empty) list
470 of the logical predecessor(s) in the line of development, i.e. its
471 parents.
473 [[def_peel]]peel::
474 The action of recursively <<def_dereference,dereferencing>> a
475 <<def_tag_object,tag object>>.
477 [[def_pickaxe]]pickaxe::
478 The term <<def_pickaxe,pickaxe>> refers to an option to the diffcore
479 routines that help select changes that add or delete a given text
480 string. With the `--pickaxe-all` option, it can be used to view the full
481 <<def_changeset,changeset>> that introduced or removed, say, a
482 particular line of text. See linkgit:git-diff[1].
484 [[def_plumbing]]plumbing::
485 Cute name for <<def_core_git,core Git>>.
487 [[def_porcelain]]porcelain::
488 Cute name for programs and program suites depending on
489 <<def_core_git,core Git>>, presenting a high level access to
490 core Git. Porcelains expose more of a <<def_SCM,SCM>>
491 interface than the <<def_plumbing,plumbing>>.
493 [[def_per_worktree_ref]]per-worktree ref::
494 Refs that are per-<<def_worktree,worktree>>, rather than
495 global. This is presently only <<def_HEAD,HEAD>> and any refs
496 that start with `refs/bisect/`, but might later include other
497 unusual refs.
499 [[def_pseudoref]]pseudoref::
500 Pseudorefs are a class of files under `$GIT_DIR` which behave
501 like refs for the purposes of rev-parse, but which are treated
502 specially by git. Pseudorefs both have names that are all-caps,
503 and always start with a line consisting of a
504 <<def_SHA1,SHA-1>> followed by whitespace. So, HEAD is not a
505 pseudoref, because it is sometimes a symbolic ref. They might
506 optionally contain some additional data. `MERGE_HEAD` and
507 `CHERRY_PICK_HEAD` are examples. Unlike
508 <<def_per_worktree_ref,per-worktree refs>>, these files cannot
509 be symbolic refs, and never have reflogs. They also cannot be
510 updated through the normal ref update machinery. Instead,
511 they are updated by directly writing to the files. However,
512 they can be read as if they were refs, so `git rev-parse
513 MERGE_HEAD` will work.
515 [[def_pull]]pull::
516 Pulling a <<def_branch,branch>> means to <<def_fetch,fetch>> it and
517 <<def_merge,merge>> it. See also linkgit:git-pull[1].
519 [[def_push]]push::
520 Pushing a <<def_branch,branch>> means to get the branch's
521 <<def_head_ref,head ref>> from a remote <<def_repository,repository>>,
522 find out if it is an ancestor to the branch's local
523 head ref, and in that case, putting all
524 objects, which are <<def_reachable,reachable>> from the local
525 head ref, and which are missing from the remote
526 repository, into the remote
527 <<def_object_database,object database>>, and updating the remote
528 head ref. If the remote <<def_head,head>> is not an
529 ancestor to the local head, the push fails.
531 [[def_reachable]]reachable::
532 All of the ancestors of a given <<def_commit,commit>> are said to be
533 "reachable" from that commit. More
534 generally, one <<def_object,object>> is reachable from
535 another if we can reach the one from the other by a <<def_chain,chain>>
536 that follows <<def_tag,tags>> to whatever they tag,
537 <<def_commit_object,commits>> to their parents or trees, and
538 <<def_tree_object,trees>> to the trees or <<def_blob_object,blobs>>
539 that they contain.
541 [[def_reachability_bitmap]]reachability bitmaps::
542 Reachability bitmaps store information about the
543 <<def_reachable,reachability>> of a selected set of commits in
544 a packfile, or a multi-pack index (MIDX), to speed up object search.
545 The bitmaps are stored in a ".bitmap" file. A repository may have at
546 most one bitmap file in use. The bitmap file may belong to either one
547 pack, or the repository's multi-pack index (if it exists).
549 [[def_rebase]]rebase::
550 To reapply a series of changes from a <<def_branch,branch>> to a
551 different base, and reset the <<def_head,head>> of that branch
552 to the result.
554 [[def_ref]]ref::
555 A name that begins with `refs/` (e.g. `refs/heads/master`)
556 that points to an <<def_object_name,object name>> or another
557 ref (the latter is called a <<def_symref,symbolic ref>>).
558 For convenience, a ref can sometimes be abbreviated when used
559 as an argument to a Git command; see linkgit:gitrevisions[7]
560 for details.
561 Refs are stored in the <<def_repository,repository>>.
562 +
563 The ref namespace is hierarchical.
564 Different subhierarchies are used for different purposes (e.g. the
565 `refs/heads/` hierarchy is used to represent local branches).
566 +
567 There are a few special-purpose refs that do not begin with `refs/`.
568 The most notable example is `HEAD`.
570 [[def_reflog]]reflog::
571 A reflog shows the local "history" of a ref. In other words,
572 it can tell you what the 3rd last revision in _this_ repository
573 was, and what was the current state in _this_ repository,
574 yesterday 9:14pm. See linkgit:git-reflog[1] for details.
576 [[def_refspec]]refspec::
577 A "refspec" is used by <<def_fetch,fetch>> and
578 <<def_push,push>> to describe the mapping between remote
579 <<def_ref,ref>> and local ref.
581 [[def_remote]]remote repository::
582 A <<def_repository,repository>> which is used to track the same
583 project but resides somewhere else. To communicate with remotes,
584 see <<def_fetch,fetch>> or <<def_push,push>>.
586 [[def_remote_tracking_branch]]remote-tracking branch::
587 A <<def_ref,ref>> that is used to follow changes from another
588 <<def_repository,repository>>. It typically looks like
589 'refs/remotes/foo/bar' (indicating that it tracks a branch named
590 'bar' in a remote named 'foo'), and matches the right-hand-side of
591 a configured fetch <<def_refspec,refspec>>. A remote-tracking
592 branch should not contain direct modifications or have local
593 commits made to it.
595 [[def_repository]]repository::
596 A collection of <<def_ref,refs>> together with an
597 <<def_object_database,object database>> containing all objects
598 which are <<def_reachable,reachable>> from the refs, possibly
599 accompanied by meta data from one or more <<def_porcelain,porcelains>>. A
600 repository can share an object database with other repositories
601 via <<def_alternate_object_database,alternates mechanism>>.
603 [[def_resolve]]resolve::
604 The action of fixing up manually what a failed automatic
605 <<def_merge,merge>> left behind.
607 [[def_revision]]revision::
608 Synonym for <<def_commit,commit>> (the noun).
610 [[def_rewind]]rewind::
611 To throw away part of the development, i.e. to assign the
612 <<def_head,head>> to an earlier <<def_revision,revision>>.
614 [[def_SCM]]SCM::
615 Source code management (tool).
617 [[def_SHA1]]SHA-1::
618 "Secure Hash Algorithm 1"; a cryptographic hash function.
619 In the context of Git used as a synonym for <<def_object_name,object name>>.
621 [[def_shallow_clone]]shallow clone::
622 Mostly a synonym to <<def_shallow_repository,shallow repository>>
623 but the phrase makes it more explicit that it was created by
624 running `git clone --depth=...` command.
626 [[def_shallow_repository]]shallow repository::
627 A shallow <<def_repository,repository>> has an incomplete
628 history some of whose <<def_commit,commits>> have <<def_parent,parents>> cauterized away (in other
629 words, Git is told to pretend that these commits do not have the
630 parents, even though they are recorded in the <<def_commit_object,commit
631 object>>). This is sometimes useful when you are interested only in the
632 recent history of a project even though the real history recorded in the
633 upstream is much larger. A shallow repository
634 is created by giving the `--depth` option to linkgit:git-clone[1], and
635 its history can be later deepened with linkgit:git-fetch[1].
637 [[def_stash]]stash entry::
638 An <<def_object,object>> used to temporarily store the contents of a
639 <<def_dirty,dirty>> working directory and the index for future reuse.
641 [[def_special_ref]]special ref::
642 A ref that has different semantics than normal refs. These refs can be
643 accessed via normal Git commands but may not behave the same as a
644 normal ref in some cases.
645 +
646 The following special refs are known to Git:
648 - "`FETCH_HEAD`" is written by linkgit:git-fetch[1] or linkgit:git-pull[1]. It
649 may refer to multiple object IDs. Each object ID is annotated with metadata
650 indicating where it was fetched from and its fetch status.
652 - "`MERGE_HEAD`" is written by linkgit:git-merge[1] when resolving merge
653 conflicts. It contains all commit IDs which are being merged.
655 [[def_submodule]]submodule::
656 A <<def_repository,repository>> that holds the history of a
657 separate project inside another repository (the latter of
658 which is called <<def_superproject, superproject>>).
660 [[def_superproject]]superproject::
661 A <<def_repository,repository>> that references repositories
662 of other projects in its working tree as <<def_submodule,submodules>>.
663 The superproject knows about the names of (but does not hold
664 copies of) commit objects of the contained submodules.
666 [[def_symref]]symref::
667 Symbolic reference: instead of containing the <<def_SHA1,SHA-1>> id
668 itself, it is of the format 'ref: refs/some/thing' and when referenced,
669 it recursively <<def_dereference,dereferences>> to this reference.
670 '<<def_HEAD,HEAD>>' is a prime example of a symref. Symbolic references
671 are manipulated with the linkgit:git-symbolic-ref[1] command.
673 [[def_tag]]tag::
674 A <<def_ref,ref>> under `refs/tags/` namespace that points to an
675 object of an arbitrary type (typically a tag points to either a
676 <<def_tag_object,tag>> or a <<def_commit_object,commit object>>).
677 In contrast to a <<def_head,head>>, a tag is not updated by
678 the `commit` command. A Git tag has nothing to do with a Lisp
679 tag (which would be called an <<def_object_type,object type>>
680 in Git's context). A tag is most typically used to mark a particular
681 point in the commit ancestry <<def_chain,chain>>.
683 [[def_tag_object]]tag object::
684 An <<def_object,object>> containing a <<def_ref,ref>> pointing to
685 another object, which can contain a message just like a
686 <<def_commit_object,commit object>>. It can also contain a (PGP)
687 signature, in which case it is called a "signed tag object".
689 [[def_topic_branch]]topic branch::
690 A regular Git <<def_branch,branch>> that is used by a developer to
691 identify a conceptual line of development. Since branches are very easy
692 and inexpensive, it is often desirable to have several small branches
693 that each contain very well defined concepts or small incremental yet
694 related changes.
696 [[def_tree]]tree::
697 Either a <<def_working_tree,working tree>>, or a <<def_tree_object,tree
698 object>> together with the dependent <<def_blob_object,blob>> and tree objects
699 (i.e. a stored representation of a working tree).
701 [[def_tree_object]]tree object::
702 An <<def_object,object>> containing a list of file names and modes along
703 with refs to the associated blob and/or tree objects. A
704 <<def_tree,tree>> is equivalent to a <<def_directory,directory>>.
706 [[def_tree-ish]]tree-ish (also treeish)::
707 A <<def_tree_object,tree object>> or an <<def_object,object>> that can
708 be recursively <<def_dereference,dereferenced>> to a tree object.
709 Dereferencing a <<def_commit_object,commit object>> yields the tree
710 object corresponding to the <<def_revision,revision>>'s top
711 <<def_directory,directory>>.
712 The following are all tree-ishes:
713 a <<def_commit-ish,commit-ish>>,
714 a tree object,
715 a <<def_tag_object,tag object>> that points to a tree object,
716 a tag object that points to a tag object that points to a tree
717 object,
718 etc.
720 [[def_unborn]]unborn::
721 The <<def_HEAD,HEAD>> can point at a <<def_branch,branch>>
722 that does not yet exist and that does not have any commit on
723 it yet, and such a branch is called an unborn branch. The
724 most typical way users encounter an unborn branch is by
725 creating a repository anew without cloning from elsewhere.
726 The HEAD would point at the 'main' (or 'master', depending
727 on your configuration) branch that is yet to be born. Also
728 some operations can get you on an unborn branch with their
729 <<def_orphan,orphan>> option.
732 [[def_unmerged_index]]unmerged index::
733 An <<def_index,index>> which contains unmerged
734 <<def_index_entry,index entries>>.
736 [[def_unreachable_object]]unreachable object::
737 An <<def_object,object>> which is not <<def_reachable,reachable>> from a
738 <<def_branch,branch>>, <<def_tag,tag>>, or any other reference.
740 [[def_upstream_branch]]upstream branch::
741 The default <<def_branch,branch>> that is merged into the branch in
742 question (or the branch in question is rebased onto). It is configured
743 via branch.<name>.remote and branch.<name>.merge. If the upstream branch
744 of 'A' is 'origin/B' sometimes we say "'A' is tracking 'origin/B'".
746 [[def_working_tree]]working tree::
747 The tree of actual checked out files. The working tree normally
748 contains the contents of the <<def_HEAD,HEAD>> commit's tree,
749 plus any local changes that you have made but not yet committed.
751 [[def_worktree]]worktree::
752 A repository can have zero (i.e. bare repository) or one or
753 more worktrees attached to it. One "worktree" consists of a
754 "working tree" and repository metadata, most of which are
755 shared among other worktrees of a single repository, and
756 some of which are maintained separately per worktree
757 (e.g. the index, HEAD and pseudorefs like MERGE_HEAD,
758 per-worktree refs and per-worktree configuration file).