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 "alternate". 5 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. 16 17[[def_blob_object]]blob object:: 18 Untyped <<def_object,object>>, e.g. the contents of a file. 19 20[[def_branch]]branch:: 21 A "branch" is an active 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 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. 30 31[[def_cache]]cache:: 32 Obsolete for: <<def_index,index>>. 33 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>>). 38 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. 43 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>>. 51 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. 59 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>>". 64 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+ 73As a verb: The action of storing a new snapshot of the project's 74state in the Git history, by creating a new commit representing the current 75state of the <<def_index,index>> and advancing <<def_HEAD,HEAD>> 76to point at the new commit. 77 78[[def_commit_object]]commit object:: 79 An <<def_object,object>> which contains the information about a 80 particular <<def_revision,revision>>, such as <<def_parent,parents>>, committer, 81 author, date and the <<def_tree_object,tree object>> which corresponds 82 to the top <<def_directory,directory>> of the stored 83 revision. 84 85[[def_commit-ish]]commit-ish (also committish):: 86 A <<def_commit_object,commit object>> or an 87 <<def_object,object>> that can be recursively dereferenced to 88 a commit object. 89 The following are all commit-ishes: 90 a commit object, 91 a <<def_tag_object,tag object>> that points to a commit 92 object, 93 a tag object that points to a tag object that points to a 94 commit object, 95 etc. 96 97[[def_core_git]]core Git:: 98 Fundamental data structures and utilities of Git. Exposes only limited 99 source code management tools. 100 101[[def_DAG]]DAG:: 102 Directed acyclic graph. The <<def_commit_object,commit objects>> form a 103 directed acyclic graph, because they have parents (directed), and the 104 graph of commit objects is acyclic (there is no <<def_chain,chain>> 105 which begins and ends with the same <<def_object,object>>). 106 107[[def_dangling_object]]dangling object:: 108 An <<def_unreachable_object,unreachable object>> which is not 109 <<def_reachable,reachable>> even from other unreachable objects; a 110 dangling object has no references to it from any 111 reference or <<def_object,object>> in the <<def_repository,repository>>. 112 113[[def_detached_HEAD]]detached HEAD:: 114 Normally the <<def_HEAD,HEAD>> stores the name of a 115 <<def_branch,branch>>, and commands that operate on the 116 history HEAD represents operate on the history leading to the 117 tip of the branch the HEAD points at. However, Git also 118 allows you to <<def_checkout,check out>> an arbitrary 119 <<def_commit,commit>> that isn't necessarily the tip of any 120 particular branch. The HEAD in such a state is called 121 "detached". 122+ 123Note that commands that operate on the history of the current branch 124(e.g. `git commit` to build a new history on top of it) still work 125while the HEAD is detached. They update the HEAD to point at the tip 126of the updated history without affecting any branch. Commands that 127update or inquire information _about_ the current branch (e.g. `git 128branch --set-upstream-to` that sets what remote-tracking branch the 129current branch integrates with) obviously do not work, as there is no 130(real) current branch to ask about in this state. 131 132[[def_directory]]directory:: 133 The list you get with "ls" :-) 134 135[[def_dirty]]dirty:: 136 A <<def_working_tree,working tree>> is said to be "dirty" if 137 it contains modifications which have not been <<def_commit,committed>> to the current 138 <<def_branch,branch>>. 139 140[[def_evil_merge]]evil merge:: 141 An evil merge is a <<def_merge,merge>> that introduces changes that 142 do not appear in any <<def_parent,parent>>. 143 144[[def_fast_forward]]fast-forward:: 145 A fast-forward is a special type of <<def_merge,merge>> where you have a 146 <<def_revision,revision>> and you are "merging" another 147 <<def_branch,branch>>'s changes that happen to be a descendant of what 148 you have. In such these cases, you do not make a new <<def_merge,merge>> 149 <<def_commit,commit>> but instead just update to his 150 revision. This will happen frequently on a 151 <<def_remote_tracking_branch,remote-tracking branch>> of a remote 152 <<def_repository,repository>>. 153 154[[def_fetch]]fetch:: 155 Fetching a <<def_branch,branch>> means to get the 156 branch's <<def_head_ref,head ref>> from a remote 157 <<def_repository,repository>>, to find out which objects are 158 missing from the local <<def_object_database,object database>>, 159 and to get them, too. See also linkgit:git-fetch[1]. 160 161[[def_file_system]]file system:: 162 Linus Torvalds originally designed Git to be a user space file system, 163 i.e. the infrastructure to hold files and directories. That ensured the 164 efficiency and speed of Git. 165 166[[def_git_archive]]Git archive:: 167 Synonym for <<def_repository,repository>> (for arch people). 168 169[[def_gitfile]]gitfile:: 170 A plain file `.git` at the root of a working tree that 171 points at the directory that is the real repository. 172 173[[def_grafts]]grafts:: 174 Grafts enables two otherwise different lines of development to be joined 175 together by recording fake ancestry information for commits. This way 176 you can make Git pretend the set of <<def_parent,parents>> a <<def_commit,commit>> has 177 is different from what was recorded when the commit was 178 created. Configured via the `.git/info/grafts` file. 179 180[[def_hash]]hash:: 181 In Git's context, synonym for <<def_object_name,object name>>. 182 183[[def_head]]head:: 184 A <<def_ref,named reference>> to the <<def_commit,commit>> at the tip of a 185 <<def_branch,branch>>. Heads are stored in a file in 186 `$GIT_DIR/refs/heads/` directory, except when using packed refs. (See 187 linkgit:git-pack-refs[1].) 188 189[[def_HEAD]]HEAD:: 190 The current <<def_branch,branch>>. In more detail: Your <<def_working_tree, 191 working tree>> is normally derived from the state of the tree 192 referred to by HEAD. HEAD is a reference to one of the 193 <<def_head,heads>> in your repository, except when using a 194 <<def_detached_HEAD,detached HEAD>>, in which case it directly 195 references an arbitrary commit. 196 197[[def_head_ref]]head ref:: 198 A synonym for <<def_head,head>>. 199 200[[def_hook]]hook:: 201 During the normal execution of several Git commands, call-outs are made 202 to optional scripts that allow a developer to add functionality or 203 checking. Typically, the hooks allow for a command to be pre-verified 204 and potentially aborted, and allow for a post-notification after the 205 operation is done. The hook scripts are found in the 206 `$GIT_DIR/hooks/` directory, and are enabled by simply 207 removing the `.sample` suffix from the filename. In earlier versions 208 of Git you had to make them executable. 209 210[[def_index]]index:: 211 A collection of files with stat information, whose contents are stored 212 as objects. The index is a stored version of your 213 <<def_working_tree,working tree>>. Truth be told, it can also contain a second, and even 214 a third version of a working tree, which are used 215 when <<def_merge,merging>>. 216 217[[def_index_entry]]index entry:: 218 The information regarding a particular file, stored in the 219 <<def_index,index>>. An index entry can be unmerged, if a 220 <<def_merge,merge>> was started, but not yet finished (i.e. if 221 the index contains multiple versions of that file). 222 223[[def_master]]master:: 224 The default development <<def_branch,branch>>. Whenever you 225 create a Git <<def_repository,repository>>, a branch named 226 "master" is created, and becomes the active branch. In most 227 cases, this contains the local development, though that is 228 purely by convention and is not required. 229 230[[def_merge]]merge:: 231 As a verb: To bring the contents of another 232 <<def_branch,branch>> (possibly from an external 233 <<def_repository,repository>>) into the current branch. In the 234 case where the merged-in branch is from a different repository, 235 this is done by first <<def_fetch,fetching>> the remote branch 236 and then merging the result into the current branch. This 237 combination of fetch and merge operations is called a 238 <<def_pull,pull>>. Merging is performed by an automatic process 239 that identifies changes made since the branches diverged, and 240 then applies all those changes together. In cases where changes 241 conflict, manual intervention may be required to complete the 242 merge. 243+ 244As a noun: unless it is a <<def_fast_forward,fast-forward>>, a 245successful merge results in the creation of a new <<def_commit,commit>> 246representing the result of the merge, and having as 247<<def_parent,parents>> the tips of the merged <<def_branch,branches>>. 248This commit is referred to as a "merge commit", or sometimes just a 249"merge". 250 251[[def_object]]object:: 252 The unit of storage in Git. It is uniquely identified by the 253 <<def_SHA1,SHA-1>> of its contents. Consequently, an 254 object can not be changed. 255 256[[def_object_database]]object database:: 257 Stores a set of "objects", and an individual <<def_object,object>> is 258 identified by its <<def_object_name,object name>>. The objects usually 259 live in `$GIT_DIR/objects/`. 260 261[[def_object_identifier]]object identifier:: 262 Synonym for <<def_object_name,object name>>. 263 264[[def_object_name]]object name:: 265 The unique identifier of an <<def_object,object>>. The 266 object name is usually represented by a 40 character 267 hexadecimal string. Also colloquially called <<def_SHA1,SHA-1>>. 268 269[[def_object_type]]object type:: 270 One of the identifiers "<<def_commit_object,commit>>", 271 "<<def_tree_object,tree>>", "<<def_tag_object,tag>>" or 272 "<<def_blob_object,blob>>" describing the type of an 273 <<def_object,object>>. 274 275[[def_octopus]]octopus:: 276 To <<def_merge,merge>> more than two <<def_branch,branches>>. 277 278[[def_origin]]origin:: 279 The default upstream <<def_repository,repository>>. Most projects have 280 at least one upstream project which they track. By default 281 'origin' is used for that purpose. New upstream updates 282 will be fetched into <<def_remote_tracking_branch,remote-tracking branches>> named 283 origin/name-of-upstream-branch, which you can see using 284 `git branch -r`. 285 286[[def_pack]]pack:: 287 A set of objects which have been compressed into one file (to save space 288 or to transmit them efficiently). 289 290[[def_pack_index]]pack index:: 291 The list of identifiers, and other information, of the objects in a 292 <<def_pack,pack>>, to assist in efficiently accessing the contents of a 293 pack. 294 295[[def_pathspec]]pathspec:: 296 Pattern used to limit paths in Git commands. 297+ 298Pathspecs are used on the command line of "git ls-files", "git 299ls-tree", "git add", "git grep", "git diff", "git checkout", 300and many other commands to 301limit the scope of operations to some subset of the tree or 302worktree. See the documentation of each command for whether 303paths are relative to the current directory or toplevel. The 304pathspec syntax is as follows: 305+ 306-- 307 308* any path matches itself 309* the pathspec up to the last slash represents a 310 directory prefix. The scope of that pathspec is 311 limited to that subtree. 312* the rest of the pathspec is a pattern for the remainder 313 of the pathname. Paths relative to the directory 314 prefix will be matched against that pattern using fnmatch(3); 315 in particular, '*' and '?' _can_ match directory separators. 316 317-- 318+ 319For example, Documentation/*.jpg will match all .jpg files 320in the Documentation subtree, 321including Documentation/chapter_1/figure_1.jpg. 322+ 323A pathspec that begins with a colon `:` has special meaning. In the 324short form, the leading colon `:` is followed by zero or more "magic 325signature" letters (which optionally is terminated by another colon `:`), 326and the remainder is the pattern to match against the path. The optional 327colon that terminates the "magic signature" can be omitted if the pattern 328begins with a character that cannot be a "magic signature" and is not a 329colon. 330+ 331In the long form, the leading colon `:` is followed by a open 332parenthesis `(`, a comma-separated list of zero or more "magic words", 333and a close parentheses `)`, and the remainder is the pattern to match 334against the path. 335+ 336The "magic signature" consists of an ASCII symbol that is not 337alphanumeric. Currently only the slash `/` is recognized as a 338"magic signature": it makes the pattern match from the root of 339the working tree, even when you are running the command from 340inside a subdirectory. 341+ 342A pathspec with only a colon means "there is no pathspec". This form 343should not be combined with other pathspec. 344 345[[def_parent]]parent:: 346 A <<def_commit_object,commit object>> contains a (possibly empty) list 347 of the logical predecessor(s) in the line of development, i.e. its 348 parents. 349 350[[def_pickaxe]]pickaxe:: 351 The term <<def_pickaxe,pickaxe>> refers to an option to the diffcore 352 routines that help select changes that add or delete a given text 353 string. With the `--pickaxe-all` option, it can be used to view the full 354 <<def_changeset,changeset>> that introduced or removed, say, a 355 particular line of text. See linkgit:git-diff[1]. 356 357[[def_plumbing]]plumbing:: 358 Cute name for <<def_core_git,core Git>>. 359 360[[def_porcelain]]porcelain:: 361 Cute name for programs and program suites depending on 362 <<def_core_git,core Git>>, presenting a high level access to 363 core Git. Porcelains expose more of a <<def_SCM,SCM>> 364 interface than the <<def_plumbing,plumbing>>. 365 366[[def_pull]]pull:: 367 Pulling a <<def_branch,branch>> means to <<def_fetch,fetch>> it and 368 <<def_merge,merge>> it. See also linkgit:git-pull[1]. 369 370[[def_push]]push:: 371 Pushing a <<def_branch,branch>> means to get the branch's 372 <<def_head_ref,head ref>> from a remote <<def_repository,repository>>, 373 find out if it is a direct ancestor to the branch's local 374 head ref, and in that case, putting all 375 objects, which are <<def_reachable,reachable>> from the local 376 head ref, and which are missing from the remote 377 repository, into the remote 378 <<def_object_database,object database>>, and updating the remote 379 head ref. If the remote <<def_head,head>> is not an 380 ancestor to the local head, the push fails. 381 382[[def_reachable]]reachable:: 383 All of the ancestors of a given <<def_commit,commit>> are said to be 384 "reachable" from that commit. More 385 generally, one <<def_object,object>> is reachable from 386 another if we can reach the one from the other by a <<def_chain,chain>> 387 that follows <<def_tag,tags>> to whatever they tag, 388 <<def_commit_object,commits>> to their parents or trees, and 389 <<def_tree_object,trees>> to the trees or <<def_blob_object,blobs>> 390 that they contain. 391 392[[def_rebase]]rebase:: 393 To reapply a series of changes from a <<def_branch,branch>> to a 394 different base, and reset the <<def_head,head>> of that branch 395 to the result. 396 397[[def_ref]]ref:: 398 A 40-byte hex representation of a <<def_SHA1,SHA-1>> or a name that 399 denotes a particular <<def_object,object>>. They may be stored in 400 a file under `$GIT_DIR/refs/` directory, or 401 in the `$GIT_DIR/packed-refs` file. 402 403[[def_reflog]]reflog:: 404 A reflog shows the local "history" of a ref. In other words, 405 it can tell you what the 3rd last revision in _this_ repository 406 was, and what was the current state in _this_ repository, 407 yesterday 9:14pm. See linkgit:git-reflog[1] for details. 408 409[[def_refspec]]refspec:: 410 A "refspec" is used by <<def_fetch,fetch>> and 411 <<def_push,push>> to describe the mapping between remote 412 <<def_ref,ref>> and local ref. 413 414[[def_remote_tracking_branch]]remote-tracking branch:: 415 A <<def_ref,ref>> that is used to follow changes from another 416 <<def_repository,repository>>. It typically looks like 417 'refs/remotes/foo/bar' (indicating that it tracks a branch named 418 'bar' in a remote named 'foo'), and matches the right-hand-side of 419 a configured fetch <<def_refspec,refspec>>. A remote-tracking 420 branch should not contain direct modifications or have local 421 commits made to it. 422 423[[def_repository]]repository:: 424 A collection of <<def_ref,refs>> together with an 425 <<def_object_database,object database>> containing all objects 426 which are <<def_reachable,reachable>> from the refs, possibly 427 accompanied by meta data from one or more <<def_porcelain,porcelains>>. A 428 repository can share an object database with other repositories 429 via <<def_alternate_object_database,alternates mechanism>>. 430 431[[def_resolve]]resolve:: 432 The action of fixing up manually what a failed automatic 433 <<def_merge,merge>> left behind. 434 435[[def_revision]]revision:: 436 Synonym for <<def_commit,commit>> (the noun). 437 438[[def_rewind]]rewind:: 439 To throw away part of the development, i.e. to assign the 440 <<def_head,head>> to an earlier <<def_revision,revision>>. 441 442[[def_SCM]]SCM:: 443 Source code management (tool). 444 445[[def_SHA1]]SHA-1:: 446 "Secure Hash Algorithm 1"; a cryptographic hash function. 447 In the context of Git used as a synonym for <<def_object_name,object name>>. 448 449[[def_shallow_repository]]shallow repository:: 450 A shallow <<def_repository,repository>> has an incomplete 451 history some of whose <<def_commit,commits>> have <<def_parent,parents>> cauterized away (in other 452 words, Git is told to pretend that these commits do not have the 453 parents, even though they are recorded in the <<def_commit_object,commit 454 object>>). This is sometimes useful when you are interested only in the 455 recent history of a project even though the real history recorded in the 456 upstream is much larger. A shallow repository 457 is created by giving the `--depth` option to linkgit:git-clone[1], and 458 its history can be later deepened with linkgit:git-fetch[1]. 459 460[[def_symref]]symref:: 461 Symbolic reference: instead of containing the <<def_SHA1,SHA-1>> 462 id itself, it is of the format 'ref: refs/some/thing' and when 463 referenced, it recursively dereferences to this reference. 464 '<<def_HEAD,HEAD>>' is a prime example of a symref. Symbolic 465 references are manipulated with the linkgit:git-symbolic-ref[1] 466 command. 467 468[[def_tag]]tag:: 469 A <<def_ref,ref>> under `refs/tags/` namespace that points to an 470 object of an arbitrary type (typically a tag points to either a 471 <<def_tag_object,tag>> or a <<def_commit_object,commit object>>). 472 In contrast to a <<def_head,head>>, a tag is not updated by 473 the `commit` command. A Git tag has nothing to do with a Lisp 474 tag (which would be called an <<def_object_type,object type>> 475 in Git's context). A tag is most typically used to mark a particular 476 point in the commit ancestry <<def_chain,chain>>. 477 478[[def_tag_object]]tag object:: 479 An <<def_object,object>> containing a <<def_ref,ref>> pointing to 480 another object, which can contain a message just like a 481 <<def_commit_object,commit object>>. It can also contain a (PGP) 482 signature, in which case it is called a "signed tag object". 483 484[[def_topic_branch]]topic branch:: 485 A regular Git <<def_branch,branch>> that is used by a developer to 486 identify a conceptual line of development. Since branches are very easy 487 and inexpensive, it is often desirable to have several small branches 488 that each contain very well defined concepts or small incremental yet 489 related changes. 490 491[[def_tree]]tree:: 492 Either a <<def_working_tree,working tree>>, or a <<def_tree_object,tree 493 object>> together with the dependent <<def_blob_object,blob>> and tree objects 494 (i.e. a stored representation of a working tree). 495 496[[def_tree_object]]tree object:: 497 An <<def_object,object>> containing a list of file names and modes along 498 with refs to the associated blob and/or tree objects. A 499 <<def_tree,tree>> is equivalent to a <<def_directory,directory>>. 500 501[[def_tree-ish]]tree-ish (also treeish):: 502 A <<def_ref,ref>> pointing to either a <<def_commit_object,commit 503 object>>, a <<def_tree_object,tree object>>, or a <<def_tag_object,tag 504 object>> pointing to a tag or commit or tree object. 505 506[[def_unmerged_index]]unmerged index:: 507 An <<def_index,index>> which contains unmerged 508 <<def_index_entry,index entries>>. 509 510[[def_unreachable_object]]unreachable object:: 511 An <<def_object,object>> which is not <<def_reachable,reachable>> from a 512 <<def_branch,branch>>, <<def_tag,tag>>, or any other reference. 513 514[[def_upstream_branch]]upstream branch:: 515 The default <<def_branch,branch>> that is merged into the branch in 516 question (or the branch in question is rebased onto). It is configured 517 via branch.<name>.remote and branch.<name>.merge. If the upstream branch 518 of 'A' is 'origin/B' sometimes we say "'A' is tracking 'origin/B'". 519 520[[def_working_tree]]working tree:: 521 The tree of actual checked out files. The working tree normally 522 contains the contents of the <<def_HEAD,HEAD>> commit's tree, 523 plus any local changes that you have made but not yet committed.