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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
102 <<def_object,object>> that can be recursively dereferenced to
103 a commit object.
104 The following are all commit-ishes:
105 a commit object,
106 a <<def_tag_object,tag object>> that points to a commit
107 object,
108 a tag object that points to a tag object that points to a
109 commit object,
110 etc.
112 [[def_core_git]]core Git::
113 Fundamental data structures and utilities of Git. Exposes only limited
114 source code management tools.
116 [[def_DAG]]DAG::
117 Directed acyclic graph. The <<def_commit_object,commit objects>> form a
118 directed acyclic graph, because they have parents (directed), and the
119 graph of commit objects is acyclic (there is no <<def_chain,chain>>
120 which begins and ends with the same <<def_object,object>>).
122 [[def_dangling_object]]dangling object::
123 An <<def_unreachable_object,unreachable object>> which is not
124 <<def_reachable,reachable>> even from other unreachable objects; a
125 dangling object has no references to it from any
126 reference or <<def_object,object>> in the <<def_repository,repository>>.
128 [[def_detached_HEAD]]detached HEAD::
129 Normally the <<def_HEAD,HEAD>> stores the name of a
130 <<def_branch,branch>>, and commands that operate on the
131 history HEAD represents operate on the history leading to the
132 tip of the branch the HEAD points at. However, Git also
133 allows you to <<def_checkout,check out>> an arbitrary
134 <<def_commit,commit>> that isn't necessarily the tip of any
135 particular branch. The HEAD in such a state is called
136 "detached".
137 +
138 Note that commands that operate on the history of the current branch
139 (e.g. `git commit` to build a new history on top of it) still work
140 while the HEAD is detached. They update the HEAD to point at the tip
141 of the updated history without affecting any branch. Commands that
142 update or inquire information _about_ the current branch (e.g. `git
143 branch --set-upstream-to` that sets what remote-tracking branch the
144 current branch integrates with) obviously do not work, as there is no
145 (real) current branch to ask about in this state.
147 [[def_directory]]directory::
148 The list you get with "ls" :-)
150 [[def_dirty]]dirty::
151 A <<def_working_tree,working tree>> is said to be "dirty" if
152 it contains modifications which have not been <<def_commit,committed>> to the current
153 <<def_branch,branch>>.
155 [[def_evil_merge]]evil merge::
156 An evil merge is a <<def_merge,merge>> that introduces changes that
157 do not appear in any <<def_parent,parent>>.
159 [[def_fast_forward]]fast-forward::
160 A fast-forward is a special type of <<def_merge,merge>> where you have a
161 <<def_revision,revision>> and you are "merging" another
162 <<def_branch,branch>>'s changes that happen to be a descendant of what
163 you have. In such a case, you do not make a new <<def_merge,merge>>
164 <<def_commit,commit>> but instead just update your branch to point at the same
165 revision as the branch you are merging. This will happen frequently on a
166 <<def_remote_tracking_branch,remote-tracking branch>> of a remote
167 <<def_repository,repository>>.
169 [[def_fetch]]fetch::
170 Fetching a <<def_branch,branch>> means to get the
171 branch's <<def_head_ref,head ref>> from a remote
172 <<def_repository,repository>>, to find out which objects are
173 missing from the local <<def_object_database,object database>>,
174 and to get them, too. See also linkgit:git-fetch[1].
176 [[def_file_system]]file system::
177 Linus Torvalds originally designed Git to be a user space file system,
178 i.e. the infrastructure to hold files and directories. That ensured the
179 efficiency and speed of Git.
181 [[def_git_archive]]Git archive::
182 Synonym for <<def_repository,repository>> (for arch people).
184 [[def_gitfile]]gitfile::
185 A plain file `.git` at the root of a working tree that
186 points at the directory that is the real repository.
188 [[def_grafts]]grafts::
189 Grafts enables two otherwise different lines of development to be joined
190 together by recording fake ancestry information for commits. This way
191 you can make Git pretend the set of <<def_parent,parents>> a <<def_commit,commit>> has
192 is different from what was recorded when the commit was
193 created. Configured via the `.git/info/grafts` file.
194 +
195 Note that the grafts mechanism is outdated and can lead to problems
196 transferring objects between repositories; see linkgit:git-replace[1]
197 for a more flexible and robust system to do the same thing.
199 [[def_hash]]hash::
200 In Git's context, synonym for <<def_object_name,object name>>.
202 [[def_head]]head::
203 A <<def_ref,named reference>> to the <<def_commit,commit>> at the tip of a
204 <<def_branch,branch>>. Heads are stored in a file in
205 `$GIT_DIR/refs/heads/` directory, except when using packed refs. (See
206 linkgit:git-pack-refs[1].)
208 [[def_HEAD]]HEAD::
209 The current <<def_branch,branch>>. In more detail: Your <<def_working_tree,
210 working tree>> is normally derived from the state of the tree
211 referred to by HEAD. HEAD is a reference to one of the
212 <<def_head,heads>> in your repository, except when using a
213 <<def_detached_HEAD,detached HEAD>>, in which case it directly
214 references an arbitrary commit.
216 [[def_head_ref]]head ref::
217 A synonym for <<def_head,head>>.
219 [[def_hook]]hook::
220 During the normal execution of several Git commands, call-outs are made
221 to optional scripts that allow a developer to add functionality or
222 checking. Typically, the hooks allow for a command to be pre-verified
223 and potentially aborted, and allow for a post-notification after the
224 operation is done. The hook scripts are found in the
225 `$GIT_DIR/hooks/` directory, and are enabled by simply
226 removing the `.sample` suffix from the filename. In earlier versions
227 of Git you had to make them executable.
229 [[def_index]]index::
230 A collection of files with stat information, whose contents are stored
231 as objects. The index is a stored version of your
232 <<def_working_tree,working tree>>. Truth be told, it can also contain a second, and even
233 a third version of a working tree, which are used
234 when <<def_merge,merging>>.
236 [[def_index_entry]]index entry::
237 The information regarding a particular file, stored in the
238 <<def_index,index>>. An index entry can be unmerged, if a
239 <<def_merge,merge>> was started, but not yet finished (i.e. if
240 the index contains multiple versions of that file).
242 [[def_master]]master::
243 The default development <<def_branch,branch>>. Whenever you
244 create a Git <<def_repository,repository>>, a branch named
245 "master" is created, and becomes the active branch. In most
246 cases, this contains the local development, though that is
247 purely by convention and is not required.
249 [[def_merge]]merge::
250 As a verb: To bring the contents of another
251 <<def_branch,branch>> (possibly from an external
252 <<def_repository,repository>>) into the current branch. In the
253 case where the merged-in branch is from a different repository,
254 this is done by first <<def_fetch,fetching>> the remote branch
255 and then merging the result into the current branch. This
256 combination of fetch and merge operations is called a
257 <<def_pull,pull>>. Merging is performed by an automatic process
258 that identifies changes made since the branches diverged, and
259 then applies all those changes together. In cases where changes
260 conflict, manual intervention may be required to complete the
261 merge.
262 +
263 As a noun: unless it is a <<def_fast_forward,fast-forward>>, a
264 successful merge results in the creation of a new <<def_commit,commit>>
265 representing the result of the merge, and having as
266 <<def_parent,parents>> the tips of the merged <<def_branch,branches>>.
267 This commit is referred to as a "merge commit", or sometimes just a
268 "merge".
270 [[def_object]]object::
271 The unit of storage in Git. It is uniquely identified by the
272 <<def_SHA1,SHA-1>> of its contents. Consequently, an
273 object cannot be changed.
275 [[def_object_database]]object database::
276 Stores a set of "objects", and an individual <<def_object,object>> is
277 identified by its <<def_object_name,object name>>. The objects usually
278 live in `$GIT_DIR/objects/`.
280 [[def_object_identifier]]object identifier (oid)::
281 Synonym for <<def_object_name,object name>>.
283 [[def_object_name]]object name::
284 The unique identifier of an <<def_object,object>>. The
285 object name is usually represented by a 40 character
286 hexadecimal string. Also colloquially called <<def_SHA1,SHA-1>>.
288 [[def_object_type]]object type::
289 One of the identifiers "<<def_commit_object,commit>>",
290 "<<def_tree_object,tree>>", "<<def_tag_object,tag>>" or
291 "<<def_blob_object,blob>>" describing the type of an
292 <<def_object,object>>.
294 [[def_octopus]]octopus::
295 To <<def_merge,merge>> more than two <<def_branch,branches>>.
297 [[def_origin]]origin::
298 The default upstream <<def_repository,repository>>. Most projects have
299 at least one upstream project which they track. By default
300 'origin' is used for that purpose. New upstream updates
301 will be fetched into <<def_remote_tracking_branch,remote-tracking branches>> named
302 origin/name-of-upstream-branch, which you can see using
303 `git branch -r`.
305 [[def_overlay]]overlay::
306 Only update and add files to the working directory, but don't
307 delete them, similar to how 'cp -R' would update the contents
308 in the destination directory. This is the default mode in a
309 <<def_checkout,checkout>> when checking out files from the
310 <<def_index,index>> or a <<def_tree-ish,tree-ish>>. In
311 contrast, no-overlay mode also deletes tracked files not
312 present in the source, similar to 'rsync --delete'.
314 [[def_pack]]pack::
315 A set of objects which have been compressed into one file (to save space
316 or to transmit them efficiently).
318 [[def_pack_index]]pack index::
319 The list of identifiers, and other information, of the objects in a
320 <<def_pack,pack>>, to assist in efficiently accessing the contents of a
321 pack.
323 [[def_pathspec]]pathspec::
324 Pattern used to limit paths in Git commands.
325 +
326 Pathspecs are used on the command line of "git ls-files", "git
327 ls-tree", "git add", "git grep", "git diff", "git checkout",
328 and many other commands to
329 limit the scope of operations to some subset of the tree or
330 working tree. See the documentation of each command for whether
331 paths are relative to the current directory or toplevel. The
332 pathspec syntax is as follows:
333 +
334 --
336 * any path matches itself
337 * the pathspec up to the last slash represents a
338 directory prefix. The scope of that pathspec is
339 limited to that subtree.
340 * the rest of the pathspec is a pattern for the remainder
341 of the pathname. Paths relative to the directory
342 prefix will be matched against that pattern using fnmatch(3);
343 in particular, '*' and '?' _can_ match directory separators.
345 --
346 +
347 For example, Documentation/*.jpg will match all .jpg files
348 in the Documentation subtree,
349 including Documentation/chapter_1/figure_1.jpg.
350 +
351 A pathspec that begins with a colon `:` has special meaning. In the
352 short form, the leading colon `:` is followed by zero or more "magic
353 signature" letters (which optionally is terminated by another colon `:`),
354 and the remainder is the pattern to match against the path.
355 The "magic signature" consists of ASCII symbols that are neither
356 alphanumeric, glob, regex special characters nor colon.
357 The optional colon that terminates the "magic signature" can be
358 omitted if the pattern begins with a character that does not belong to
359 "magic signature" symbol set and is not a colon.
360 +
361 In the long form, the leading colon `:` is followed by an open
362 parenthesis `(`, a comma-separated list of zero or more "magic words",
363 and a close parentheses `)`, and the remainder is the pattern to match
364 against the path.
365 +
366 A pathspec with only a colon means "there is no pathspec". This form
367 should not be combined with other pathspec.
368 +
369 --
370 top;;
371 The magic word `top` (magic signature: `/`) makes the pattern
372 match from the root of the working tree, even when you are
373 running the command from inside a subdirectory.
375 literal;;
376 Wildcards in the pattern such as `*` or `?` are treated
377 as literal characters.
379 icase;;
380 Case insensitive match.
382 glob;;
383 Git treats the pattern as a shell glob suitable for
384 consumption by fnmatch(3) with the FNM_PATHNAME flag:
385 wildcards in the pattern will not match a / in the pathname.
386 For example, "Documentation/{asterisk}.html" matches
387 "Documentation/git.html" but not "Documentation/ppc/ppc.html"
388 or "tools/perf/Documentation/perf.html".
389 +
390 Two consecutive asterisks ("`**`") in patterns matched against
391 full pathname may have special meaning:
393 - A leading "`**`" followed by a slash means match in all
394 directories. For example, "`**/foo`" matches file or directory
395 "`foo`" anywhere, the same as pattern "`foo`". "`**/foo/bar`"
396 matches file or directory "`bar`" anywhere that is directly
397 under directory "`foo`".
399 - A trailing "`/**`" matches everything inside. For example,
400 "`abc/**`" matches all files inside directory "abc", relative
401 to the location of the `.gitignore` file, with infinite depth.
403 - A slash followed by two consecutive asterisks then a slash
404 matches zero or more directories. For example, "`a/**/b`"
405 matches "`a/b`", "`a/x/b`", "`a/x/y/b`" and so on.
407 - Other consecutive asterisks are considered invalid.
408 +
409 Glob magic is incompatible with literal magic.
411 attr;;
412 After `attr:` comes a space separated list of "attribute
413 requirements", all of which must be met in order for the
414 path to be considered a match; this is in addition to the
415 usual non-magic pathspec pattern matching.
416 See linkgit:gitattributes[5].
417 +
418 Each of the attribute requirements for the path takes one of
419 these forms:
421 - "`ATTR`" requires that the attribute `ATTR` be set.
423 - "`-ATTR`" requires that the attribute `ATTR` be unset.
425 - "`ATTR=VALUE`" requires that the attribute `ATTR` be
426 set to the string `VALUE`.
428 - "`!ATTR`" requires that the attribute `ATTR` be
429 unspecified.
430 +
431 Note that when matching against a tree object, attributes are still
432 obtained from working tree, not from the given tree object.
434 exclude;;
435 After a path matches any non-exclude pathspec, it will be run
436 through all exclude pathspecs (magic signature: `!` or its
437 synonym `^`). If it matches, the path is ignored. When there
438 is no non-exclude pathspec, the exclusion is applied to the
439 result set as if invoked without any pathspec.
440 --
442 [[def_parent]]parent::
443 A <<def_commit_object,commit object>> contains a (possibly empty) list
444 of the logical predecessor(s) in the line of development, i.e. its
445 parents.
447 [[def_pickaxe]]pickaxe::
448 The term <<def_pickaxe,pickaxe>> refers to an option to the diffcore
449 routines that help select changes that add or delete a given text
450 string. With the `--pickaxe-all` option, it can be used to view the full
451 <<def_changeset,changeset>> that introduced or removed, say, a
452 particular line of text. See linkgit:git-diff[1].
454 [[def_plumbing]]plumbing::
455 Cute name for <<def_core_git,core Git>>.
457 [[def_porcelain]]porcelain::
458 Cute name for programs and program suites depending on
459 <<def_core_git,core Git>>, presenting a high level access to
460 core Git. Porcelains expose more of a <<def_SCM,SCM>>
461 interface than the <<def_plumbing,plumbing>>.
463 [[def_per_worktree_ref]]per-worktree ref::
464 Refs that are per-<<def_worktree,worktree>>, rather than
465 global. This is presently only <<def_HEAD,HEAD>> and any refs
466 that start with `refs/bisect/`, but might later include other
467 unusual refs.
469 [[def_pseudoref]]pseudoref::
470 Pseudorefs are a class of files under `$GIT_DIR` which behave
471 like refs for the purposes of rev-parse, but which are treated
472 specially by git. Pseudorefs both have names that are all-caps,
473 and always start with a line consisting of a
474 <<def_SHA1,SHA-1>> followed by whitespace. So, HEAD is not a
475 pseudoref, because it is sometimes a symbolic ref. They might
476 optionally contain some additional data. `MERGE_HEAD` and
477 `CHERRY_PICK_HEAD` are examples. Unlike
478 <<def_per_worktree_ref,per-worktree refs>>, these files cannot
479 be symbolic refs, and never have reflogs. They also cannot be
480 updated through the normal ref update machinery. Instead,
481 they are updated by directly writing to the files. However,
482 they can be read as if they were refs, so `git rev-parse
483 MERGE_HEAD` will work.
485 [[def_pull]]pull::
486 Pulling a <<def_branch,branch>> means to <<def_fetch,fetch>> it and
487 <<def_merge,merge>> it. See also linkgit:git-pull[1].
489 [[def_push]]push::
490 Pushing a <<def_branch,branch>> means to get the branch's
491 <<def_head_ref,head ref>> from a remote <<def_repository,repository>>,
492 find out if it is an ancestor to the branch's local
493 head ref, and in that case, putting all
494 objects, which are <<def_reachable,reachable>> from the local
495 head ref, and which are missing from the remote
496 repository, into the remote
497 <<def_object_database,object database>>, and updating the remote
498 head ref. If the remote <<def_head,head>> is not an
499 ancestor to the local head, the push fails.
501 [[def_reachable]]reachable::
502 All of the ancestors of a given <<def_commit,commit>> are said to be
503 "reachable" from that commit. More
504 generally, one <<def_object,object>> is reachable from
505 another if we can reach the one from the other by a <<def_chain,chain>>
506 that follows <<def_tag,tags>> to whatever they tag,
507 <<def_commit_object,commits>> to their parents or trees, and
508 <<def_tree_object,trees>> to the trees or <<def_blob_object,blobs>>
509 that they contain.
511 [[def_reachability_bitmap]]reachability bitmaps::
512 Reachability bitmaps store information about the
513 <<def_reachable,reachability>> of a selected set of commits in
514 a packfile, or a multi-pack index (MIDX), to speed up object search.
515 The bitmaps are stored in a ".bitmap" file. A repository may have at
516 most one bitmap file in use. The bitmap file may belong to either one
517 pack, or the repository's multi-pack index (if it exists).
519 [[def_rebase]]rebase::
520 To reapply a series of changes from a <<def_branch,branch>> to a
521 different base, and reset the <<def_head,head>> of that branch
522 to the result.
524 [[def_ref]]ref::
525 A name that begins with `refs/` (e.g. `refs/heads/master`)
526 that points to an <<def_object_name,object name>> or another
527 ref (the latter is called a <<def_symref,symbolic ref>>).
528 For convenience, a ref can sometimes be abbreviated when used
529 as an argument to a Git command; see linkgit:gitrevisions[7]
530 for details.
531 Refs are stored in the <<def_repository,repository>>.
532 +
533 The ref namespace is hierarchical.
534 Different subhierarchies are used for different purposes (e.g. the
535 `refs/heads/` hierarchy is used to represent local branches).
536 +
537 There are a few special-purpose refs that do not begin with `refs/`.
538 The most notable example is `HEAD`.
540 [[def_reflog]]reflog::
541 A reflog shows the local "history" of a ref. In other words,
542 it can tell you what the 3rd last revision in _this_ repository
543 was, and what was the current state in _this_ repository,
544 yesterday 9:14pm. See linkgit:git-reflog[1] for details.
546 [[def_refspec]]refspec::
547 A "refspec" is used by <<def_fetch,fetch>> and
548 <<def_push,push>> to describe the mapping between remote
549 <<def_ref,ref>> and local ref.
551 [[def_remote]]remote repository::
552 A <<def_repository,repository>> which is used to track the same
553 project but resides somewhere else. To communicate with remotes,
554 see <<def_fetch,fetch>> or <<def_push,push>>.
556 [[def_remote_tracking_branch]]remote-tracking branch::
557 A <<def_ref,ref>> that is used to follow changes from another
558 <<def_repository,repository>>. It typically looks like
559 'refs/remotes/foo/bar' (indicating that it tracks a branch named
560 'bar' in a remote named 'foo'), and matches the right-hand-side of
561 a configured fetch <<def_refspec,refspec>>. A remote-tracking
562 branch should not contain direct modifications or have local
563 commits made to it.
565 [[def_repository]]repository::
566 A collection of <<def_ref,refs>> together with an
567 <<def_object_database,object database>> containing all objects
568 which are <<def_reachable,reachable>> from the refs, possibly
569 accompanied by meta data from one or more <<def_porcelain,porcelains>>. A
570 repository can share an object database with other repositories
571 via <<def_alternate_object_database,alternates mechanism>>.
573 [[def_resolve]]resolve::
574 The action of fixing up manually what a failed automatic
575 <<def_merge,merge>> left behind.
577 [[def_revision]]revision::
578 Synonym for <<def_commit,commit>> (the noun).
580 [[def_rewind]]rewind::
581 To throw away part of the development, i.e. to assign the
582 <<def_head,head>> to an earlier <<def_revision,revision>>.
584 [[def_SCM]]SCM::
585 Source code management (tool).
587 [[def_SHA1]]SHA-1::
588 "Secure Hash Algorithm 1"; a cryptographic hash function.
589 In the context of Git used as a synonym for <<def_object_name,object name>>.
591 [[def_shallow_clone]]shallow clone::
592 Mostly a synonym to <<def_shallow_repository,shallow repository>>
593 but the phrase makes it more explicit that it was created by
594 running `git clone --depth=...` command.
596 [[def_shallow_repository]]shallow repository::
597 A shallow <<def_repository,repository>> has an incomplete
598 history some of whose <<def_commit,commits>> have <<def_parent,parents>> cauterized away (in other
599 words, Git is told to pretend that these commits do not have the
600 parents, even though they are recorded in the <<def_commit_object,commit
601 object>>). This is sometimes useful when you are interested only in the
602 recent history of a project even though the real history recorded in the
603 upstream is much larger. A shallow repository
604 is created by giving the `--depth` option to linkgit:git-clone[1], and
605 its history can be later deepened with linkgit:git-fetch[1].
607 [[def_stash]]stash entry::
608 An <<def_object,object>> used to temporarily store the contents of a
609 <<def_dirty,dirty>> working directory and the index for future reuse.
611 [[def_submodule]]submodule::
612 A <<def_repository,repository>> that holds the history of a
613 separate project inside another repository (the latter of
614 which is called <<def_superproject, superproject>>).
616 [[def_superproject]]superproject::
617 A <<def_repository,repository>> that references repositories
618 of other projects in its working tree as <<def_submodule,submodules>>.
619 The superproject knows about the names of (but does not hold
620 copies of) commit objects of the contained submodules.
622 [[def_symref]]symref::
623 Symbolic reference: instead of containing the <<def_SHA1,SHA-1>>
624 id itself, it is of the format 'ref: refs/some/thing' and when
625 referenced, it recursively dereferences to this reference.
626 '<<def_HEAD,HEAD>>' is a prime example of a symref. Symbolic
627 references are manipulated with the linkgit:git-symbolic-ref[1]
628 command.
630 [[def_tag]]tag::
631 A <<def_ref,ref>> under `refs/tags/` namespace that points to an
632 object of an arbitrary type (typically a tag points to either a
633 <<def_tag_object,tag>> or a <<def_commit_object,commit object>>).
634 In contrast to a <<def_head,head>>, a tag is not updated by
635 the `commit` command. A Git tag has nothing to do with a Lisp
636 tag (which would be called an <<def_object_type,object type>>
637 in Git's context). A tag is most typically used to mark a particular
638 point in the commit ancestry <<def_chain,chain>>.
640 [[def_tag_object]]tag object::
641 An <<def_object,object>> containing a <<def_ref,ref>> pointing to
642 another object, which can contain a message just like a
643 <<def_commit_object,commit object>>. It can also contain a (PGP)
644 signature, in which case it is called a "signed tag object".
646 [[def_topic_branch]]topic branch::
647 A regular Git <<def_branch,branch>> that is used by a developer to
648 identify a conceptual line of development. Since branches are very easy
649 and inexpensive, it is often desirable to have several small branches
650 that each contain very well defined concepts or small incremental yet
651 related changes.
653 [[def_tree]]tree::
654 Either a <<def_working_tree,working tree>>, or a <<def_tree_object,tree
655 object>> together with the dependent <<def_blob_object,blob>> and tree objects
656 (i.e. a stored representation of a working tree).
658 [[def_tree_object]]tree object::
659 An <<def_object,object>> containing a list of file names and modes along
660 with refs to the associated blob and/or tree objects. A
661 <<def_tree,tree>> is equivalent to a <<def_directory,directory>>.
663 [[def_tree-ish]]tree-ish (also treeish)::
664 A <<def_tree_object,tree object>> or an <<def_object,object>>
665 that can be recursively dereferenced to a tree object.
666 Dereferencing a <<def_commit_object,commit object>> yields the
667 tree object corresponding to the <<def_revision,revision>>'s
668 top <<def_directory,directory>>.
669 The following are all tree-ishes:
670 a <<def_commit-ish,commit-ish>>,
671 a tree object,
672 a <<def_tag_object,tag object>> that points to a tree object,
673 a tag object that points to a tag object that points to a tree
674 object,
675 etc.
677 [[def_unmerged_index]]unmerged index::
678 An <<def_index,index>> which contains unmerged
679 <<def_index_entry,index entries>>.
681 [[def_unreachable_object]]unreachable object::
682 An <<def_object,object>> which is not <<def_reachable,reachable>> from a
683 <<def_branch,branch>>, <<def_tag,tag>>, or any other reference.
685 [[def_upstream_branch]]upstream branch::
686 The default <<def_branch,branch>> that is merged into the branch in
687 question (or the branch in question is rebased onto). It is configured
688 via branch.<name>.remote and branch.<name>.merge. If the upstream branch
689 of 'A' is 'origin/B' sometimes we say "'A' is tracking 'origin/B'".
691 [[def_working_tree]]working tree::
692 The tree of actual checked out files. The working tree normally
693 contains the contents of the <<def_HEAD,HEAD>> commit's tree,
694 plus any local changes that you have made but not yet committed.
696 [[def_worktree]]worktree::
697 A repository can have zero (i.e. bare repository) or one or
698 more worktrees attached to it. One "worktree" consists of a
699 "working tree" and repository metadata, most of which are
700 shared among other worktrees of a single repository, and
701 some of which are maintained separately per worktree
702 (e.g. the index, HEAD and pseudorefs like MERGE_HEAD,
703 per-worktree refs and per-worktree configuration file).