Documentation/glossary-content.txt

   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 +
  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.
  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_core_git]]core git::
  86         Fundamental data structures and utilities of git. Exposes only limited
  87         source code management tools.
  88
  89 [[def_DAG]]DAG::
  90         Directed acyclic graph. The <<def_commit_object,commit objects>> form a
  91         directed acyclic graph, because they have parents (directed), and the
  92         graph of commit objects is acyclic (there is no <<def_chain,chain>>
  93         which begins and ends with the same <<def_object,object>>).
  94
  95 [[def_dangling_object]]dangling object::
  96         An <<def_unreachable_object,unreachable object>> which is not
  97         <<def_reachable,reachable>> even from other unreachable objects; a
  98         dangling object has no references to it from any
  99         reference or <<def_object,object>> in the <<def_repository,repository>>.
 100
 101 [[def_detached_HEAD]]detached HEAD::
 102         Normally the <<def_HEAD,HEAD>> stores the name of a
 103         <<def_branch,branch>>.  However, git also allows you to <<def_checkout,check out>>
 104         an arbitrary <<def_commit,commit>> that isn't necessarily the tip of any
 105         particular branch.  In this case HEAD is said to be "detached".
 106
 107 [[def_dircache]]dircache::
 108         You are *waaaaay* behind. See <<def_index,index>>.
 109
 110 [[def_directory]]directory::
 111         The list you get with "ls" :-)
 112
 113 [[def_dirty]]dirty::
 114         A <<def_working_tree,working tree>> is said to be "dirty" if
 115         it contains modifications which have not been <<def_commit,committed>> to the current
 116         <<def_branch,branch>>.
 117
 118 [[def_ent]]ent::
 119         Favorite synonym to "<<def_tree-ish,tree-ish>>" by some total geeks. See
 120         http://en.wikipedia.org/wiki/Ent_(Middle-earth) for an in-depth
 121         explanation. Avoid this term, not to confuse people.
 122
 123 [[def_evil_merge]]evil merge::
 124         An evil merge is a <<def_merge,merge>> that introduces changes that
 125         do not appear in any <<def_parent,parent>>.
 126
 127 [[def_fast_forward]]fast-forward::
 128         A fast-forward is a special type of <<def_merge,merge>> where you have a
 129         <<def_revision,revision>> and you are "merging" another
 130         <<def_branch,branch>>'s changes that happen to be a descendant of what
 131         you have. In such these cases, you do not make a new <<def_merge,merge>>
 132         <<def_commit,commit>> but instead just update to his
 133         revision. This will happen frequently on a
 134         <<def_remote_tracking_branch,remote-tracking branch>> of a remote
 135         <<def_repository,repository>>.
 136
 137 [[def_fetch]]fetch::
 138         Fetching a <<def_branch,branch>> means to get the
 139         branch's <<def_head_ref,head ref>> from a remote
 140         <<def_repository,repository>>, to find out which objects are
 141         missing from the local <<def_object_database,object database>>,
 142         and to get them, too.  See also linkgit:git-fetch[1].
 143
 144 [[def_file_system]]file system::
 145         Linus Torvalds originally designed git to be a user space file system,
 146         i.e. the infrastructure to hold files and directories. That ensured the
 147         efficiency and speed of git.
 148
 149 [[def_git_archive]]git archive::
 150         Synonym for <<def_repository,repository>> (for arch people).
 151
 152 [[def_grafts]]grafts::
 153         Grafts enables two otherwise different lines of development to be joined
 154         together by recording fake ancestry information for commits. This way
 155         you can make git pretend the set of <<def_parent,parents>> a <<def_commit,commit>> has
 156         is different from what was recorded when the commit was
 157         created. Configured via the `.git/info/grafts` file.
 158
 159 [[def_hash]]hash::
 160         In git's context, synonym to <<def_object_name,object name>>.
 161
 162 [[def_head]]head::
 163         A <<def_ref,named reference>> to the <<def_commit,commit>> at the tip of a
 164         <<def_branch,branch>>.  Heads are stored in a file in
 165         `$GIT_DIR/refs/heads/` directory, except when using packed refs. (See
 166         linkgit:git-pack-refs[1].)
 167
 168 [[def_HEAD]]HEAD::
 169         The current <<def_branch,branch>>.  In more detail: Your <<def_working_tree,
 170         working tree>> is normally derived from the state of the tree
 171         referred to by HEAD.  HEAD is a reference to one of the
 172         <<def_head,heads>> in your repository, except when using a
 173         <<def_detached_HEAD,detached HEAD>>, in which case it directly
 174         references an arbitrary commit.
 175
 176 [[def_head_ref]]head ref::
 177         A synonym for <<def_head,head>>.
 178
 179 [[def_hook]]hook::
 180         During the normal execution of several git commands, call-outs are made
 181         to optional scripts that allow a developer to add functionality or
 182         checking. Typically, the hooks allow for a command to be pre-verified
 183         and potentially aborted, and allow for a post-notification after the
 184         operation is done. The hook scripts are found in the
 185         `$GIT_DIR/hooks/` directory, and are enabled by simply
 186         removing the `.sample` suffix from the filename. In earlier versions
 187         of git you had to make them executable.
 188
 189 [[def_index]]index::
 190         A collection of files with stat information, whose contents are stored
 191         as objects. The index is a stored version of your
 192         <<def_working_tree,working tree>>. Truth be told, it can also contain a second, and even
 193         a third version of a working tree, which are used
 194         when <<def_merge,merging>>.
 195
 196 [[def_index_entry]]index entry::
 197         The information regarding a particular file, stored in the
 198         <<def_index,index>>. An index entry can be unmerged, if a
 199         <<def_merge,merge>> was started, but not yet finished (i.e. if
 200         the index contains multiple versions of that file).
 201
 202 [[def_master]]master::
 203         The default development <<def_branch,branch>>. Whenever you
 204         create a git <<def_repository,repository>>, a branch named
 205         "master" is created, and becomes the active branch. In most
 206         cases, this contains the local development, though that is
 207         purely by convention and is not required.
 208
 209 [[def_merge]]merge::
 210         As a verb: To bring the contents of another
 211         <<def_branch,branch>> (possibly from an external
 212         <<def_repository,repository>>) into the current branch.  In the
 213         case where the merged-in branch is from a different repository,
 214         this is done by first <<def_fetch,fetching>> the remote branch
 215         and then merging the result into the current branch.  This
 216         combination of fetch and merge operations is called a
 217         <<def_pull,pull>>.  Merging is performed by an automatic process
 218         that identifies changes made since the branches diverged, and
 219         then applies all those changes together.  In cases where changes
 220         conflict, manual intervention may be required to complete the
 221         merge.
 222 +
 223 As a noun: unless it is a <<def_fast_forward,fast-forward>>, a
 224 successful merge results in the creation of a new <<def_commit,commit>>
 225 representing the result of the merge, and having as
 226 <<def_parent,parents>> the tips of the merged <<def_branch,branches>>.
 227 This commit is referred to as a "merge commit", or sometimes just a
 228 "merge".
 229
 230 [[def_object]]object::
 231         The unit of storage in git. It is uniquely identified by the
 232         <<def_SHA1,SHA1>> of its contents. Consequently, an
 233         object can not be changed.
 234
 235 [[def_object_database]]object database::
 236         Stores a set of "objects", and an individual <<def_object,object>> is
 237         identified by its <<def_object_name,object name>>. The objects usually
 238         live in `$GIT_DIR/objects/`.
 239
 240 [[def_object_identifier]]object identifier::
 241         Synonym for <<def_object_name,object name>>.
 242
 243 [[def_object_name]]object name::
 244         The unique identifier of an <<def_object,object>>. The <<def_hash,hash>>
 245         of the object's contents using the Secure Hash Algorithm
 246         1 and usually represented by the 40 character hexadecimal encoding of
 247         the <<def_hash,hash>> of the object.
 248
 249 [[def_object_type]]object type::
 250         One of the identifiers "<<def_commit_object,commit>>",
 251         "<<def_tree_object,tree>>", "<<def_tag_object,tag>>" or
 252         "<<def_blob_object,blob>>" describing the type of an
 253         <<def_object,object>>.
 254
 255 [[def_octopus]]octopus::
 256         To <<def_merge,merge>> more than two <<def_branch,branches>>. Also denotes an
 257         intelligent predator.
 258
 259 [[def_origin]]origin::
 260         The default upstream <<def_repository,repository>>. Most projects have
 261         at least one upstream project which they track. By default
 262         'origin' is used for that purpose. New upstream updates
 263         will be fetched into remote <<def_remote_tracking_branch,remote-tracking branches>> named
 264         origin/name-of-upstream-branch, which you can see using
 265         `git branch -r`.
 266
 267 [[def_pack]]pack::
 268         A set of objects which have been compressed into one file (to save space
 269         or to transmit them efficiently).
 270
 271 [[def_pack_index]]pack index::
 272         The list of identifiers, and other information, of the objects in a
 273         <<def_pack,pack>>, to assist in efficiently accessing the contents of a
 274         pack.
 275
 276 [[def_pathspec]]pathspec::
 277        Pattern used to specify paths.
 278 +
 279 Pathspecs are used on the command line of "git ls-files", "git
 280 ls-tree", "git add", "git grep", "git diff", "git checkout",
 281 and many other commands to
 282 limit the scope of operations to some subset of the tree or
 283 worktree.  See the documentation of each command for whether
 284 paths are relative to the current directory or toplevel.  The
 285 pathspec syntax is as follows:
 286
 287 * any path matches itself
 288 * the pathspec up to the last slash represents a
 289   directory prefix.  The scope of that pathspec is
 290   limited to that subtree.
 291 * the rest of the pathspec is a pattern for the remainder
 292   of the pathname.  Paths relative to the directory
 293   prefix will be matched against that pattern using fnmatch(3);
 294   in particular, '*' and '?' _can_ match directory separators.
 295 +
 296 For example, Documentation/*.jpg will match all .jpg files
 297 in the Documentation subtree,
 298 including Documentation/chapter_1/figure_1.jpg.
 299
 300 +
 301 A pathspec that begins with a colon `:` has special meaning.  In the
 302 short form, the leading colon `:` is followed by zero or more "magic
 303 signature" letters (which optionally is terminated by another colon `:`),
 304 and the remainder is the pattern to match against the path. The optional
 305 colon that terminates the "magic signature" can be omitted if the pattern
 306 begins with a character that cannot be a "magic signature" and is not a
 307 colon.
 308 +
 309 In the long form, the leading colon `:` is followed by a open
 310 parenthesis `(`, a comma-separated list of zero or more "magic words",
 311 and a close parentheses `)`, and the remainder is the pattern to match
 312 against the path.
 313 +
 314 The "magic signature" consists of an ASCII symbol that is not
 315 alphanumeric.
 316 +
 317 --
 318 top `/`;;
 319         The magic word `top` (mnemonic: `/`) makes the pattern match
 320         from the root of the working tree, even when you are running
 321         the command from inside a subdirectory.
 322 --
 323 +
 324 Currently only the slash `/` is recognized as the "magic signature",
 325 but it is envisioned that we will support more types of magic in later
 326 versions of git.
 327 +
 328 A pathspec with only a colon means "there is no pathspec". This form
 329 should not be combined with other pathspec.
 330
 331 [[def_parent]]parent::
 332         A <<def_commit_object,commit object>> contains a (possibly empty) list
 333         of the logical predecessor(s) in the line of development, i.e. its
 334         parents.
 335
 336 [[def_pickaxe]]pickaxe::
 337         The term <<def_pickaxe,pickaxe>> refers to an option to the diffcore
 338         routines that help select changes that add or delete a given text
 339         string. With the `--pickaxe-all` option, it can be used to view the full
 340         <<def_changeset,changeset>> that introduced or removed, say, a
 341         particular line of text. See linkgit:git-diff[1].
 342
 343 [[def_plumbing]]plumbing::
 344         Cute name for <<def_core_git,core git>>.
 345
 346 [[def_porcelain]]porcelain::
 347         Cute name for programs and program suites depending on
 348         <<def_core_git,core git>>, presenting a high level access to
 349         core git. Porcelains expose more of a <<def_SCM,SCM>>
 350         interface than the <<def_plumbing,plumbing>>.
 351
 352 [[def_pull]]pull::
 353         Pulling a <<def_branch,branch>> means to <<def_fetch,fetch>> it and
 354         <<def_merge,merge>> it.  See also linkgit:git-pull[1].
 355
 356 [[def_push]]push::
 357         Pushing a <<def_branch,branch>> means to get the branch's
 358         <<def_head_ref,head ref>> from a remote <<def_repository,repository>>,
 359         find out if it is a direct ancestor to the branch's local
 360         head ref, and in that case, putting all
 361         objects, which are <<def_reachable,reachable>> from the local
 362         head ref, and which are missing from the remote
 363         repository, into the remote
 364         <<def_object_database,object database>>, and updating the remote
 365         head ref. If the remote <<def_head,head>> is not an
 366         ancestor to the local head, the push fails.
 367
 368 [[def_reachable]]reachable::
 369         All of the ancestors of a given <<def_commit,commit>> are said to be
 370         "reachable" from that commit. More
 371         generally, one <<def_object,object>> is reachable from
 372         another if we can reach the one from the other by a <<def_chain,chain>>
 373         that follows <<def_tag,tags>> to whatever they tag,
 374         <<def_commit_object,commits>> to their parents or trees, and
 375         <<def_tree_object,trees>> to the trees or <<def_blob_object,blobs>>
 376         that they contain.
 377
 378 [[def_rebase]]rebase::
 379         To reapply a series of changes from a <<def_branch,branch>> to a
 380         different base, and reset the <<def_head,head>> of that branch
 381         to the result.
 382
 383 [[def_ref]]ref::
 384         A 40-byte hex representation of a <<def_SHA1,SHA1>> or a name that
 385         denotes a particular <<def_object,object>>. They may be stored in
 386         a file under `$GIT_DIR/refs/` directory, or
 387         in the `$GIT_DIR/packed-refs` file.
 388
 389 [[def_reflog]]reflog::
 390         A reflog shows the local "history" of a ref.  In other words,
 391         it can tell you what the 3rd last revision in _this_ repository
 392         was, and what was the current state in _this_ repository,
 393         yesterday 9:14pm.  See linkgit:git-reflog[1] for details.
 394
 395 [[def_refspec]]refspec::
 396         A "refspec" is used by <<def_fetch,fetch>> and
 397         <<def_push,push>> to describe the mapping between remote
 398         <<def_ref,ref>> and local ref. They are combined with a colon in
 399         the format <src>:<dst>, preceded by an optional plus sign, +.
 400         For example: `git fetch $URL
 401         refs/heads/master:refs/heads/origin` means "grab the master
 402         <<def_branch,branch>> <<def_head,head>> from the $URL and store
 403         it as my origin branch head". And `git push
 404         $URL refs/heads/master:refs/heads/to-upstream` means "publish my
 405         master branch head as to-upstream branch at $URL". See also
 406         linkgit:git-push[1].
 407
 408 [[def_remote_tracking_branch]]remote-tracking branch::
 409         A regular git <<def_branch,branch>> that is used to follow changes from
 410         another <<def_repository,repository>>. A remote-tracking
 411         branch should not contain direct modifications or have local commits
 412         made to it. A remote-tracking branch can usually be
 413         identified as the right-hand-side <<def_ref,ref>> in a Pull:
 414         <<def_refspec,refspec>>.
 415
 416 [[def_repository]]repository::
 417         A collection of <<def_ref,refs>> together with an
 418         <<def_object_database,object database>> containing all objects
 419         which are <<def_reachable,reachable>> from the refs, possibly
 420         accompanied by meta data from one or more <<def_porcelain,porcelains>>. A
 421         repository can share an object database with other repositories
 422         via <<def_alternate_object_database,alternates mechanism>>.
 423
 424 [[def_resolve]]resolve::
 425         The action of fixing up manually what a failed automatic
 426         <<def_merge,merge>> left behind.
 427
 428 [[def_revision]]revision::
 429         A particular state of files and directories which was stored in the
 430         <<def_object_database,object database>>. It is referenced by a
 431         <<def_commit_object,commit object>>.
 432
 433 [[def_rewind]]rewind::
 434         To throw away part of the development, i.e. to assign the
 435         <<def_head,head>> to an earlier <<def_revision,revision>>.
 436
 437 [[def_SCM]]SCM::
 438         Source code management (tool).
 439
 440 [[def_SHA1]]SHA1::
 441         Synonym for <<def_object_name,object name>>.
 442
 443 [[def_shallow_repository]]shallow repository::
 444         A shallow <<def_repository,repository>> has an incomplete
 445         history some of whose <<def_commit,commits>> have <<def_parent,parents>> cauterized away (in other
 446         words, git is told to pretend that these commits do not have the
 447         parents, even though they are recorded in the <<def_commit_object,commit
 448         object>>). This is sometimes useful when you are interested only in the
 449         recent history of a project even though the real history recorded in the
 450         upstream is much larger. A shallow repository
 451         is created by giving the `--depth` option to linkgit:git-clone[1], and
 452         its history can be later deepened with linkgit:git-fetch[1].
 453
 454 [[def_symref]]symref::
 455         Symbolic reference: instead of containing the <<def_SHA1,SHA1>>
 456         id itself, it is of the format 'ref: refs/some/thing' and when
 457         referenced, it recursively dereferences to this reference.
 458         '<<def_HEAD,HEAD>>' is a prime example of a symref. Symbolic
 459         references are manipulated with the linkgit:git-symbolic-ref[1]
 460         command.
 461
 462 [[def_tag]]tag::
 463         A <<def_ref,ref>> under `refs/tags/` namespace that points to an
 464         object of an arbitrary type (typically a tag points to either a
 465         <<def_tag_object,tag>> or a <<def_commit_object,commit object>>).
 466         In contrast to a <<def_head,head>>, a tag is not updated by
 467         the `commit` command. A git tag has nothing to do with a Lisp
 468         tag (which would be called an <<def_object_type,object type>>
 469         in git's context). A tag is most typically used to mark a particular
 470         point in the commit ancestry <<def_chain,chain>>.
 471
 472 [[def_tag_object]]tag object::
 473         An <<def_object,object>> containing a <<def_ref,ref>> pointing to
 474         another object, which can contain a message just like a
 475         <<def_commit_object,commit object>>. It can also contain a (PGP)
 476         signature, in which case it is called a "signed tag object".
 477
 478 [[def_topic_branch]]topic branch::
 479         A regular git <<def_branch,branch>> that is used by a developer to
 480         identify a conceptual line of development. Since branches are very easy
 481         and inexpensive, it is often desirable to have several small branches
 482         that each contain very well defined concepts or small incremental yet
 483         related changes.
 484
 485 [[def_tree]]tree::
 486         Either a <<def_working_tree,working tree>>, or a <<def_tree_object,tree
 487         object>> together with the dependent <<def_blob_object,blob>> and tree objects
 488         (i.e. a stored representation of a working tree).
 489
 490 [[def_tree_object]]tree object::
 491         An <<def_object,object>> containing a list of file names and modes along
 492         with refs to the associated blob and/or tree objects. A
 493         <<def_tree,tree>> is equivalent to a <<def_directory,directory>>.
 494
 495 [[def_tree-ish]]tree-ish::
 496         A <<def_ref,ref>> pointing to either a <<def_commit_object,commit
 497         object>>, a <<def_tree_object,tree object>>, or a <<def_tag_object,tag
 498         object>> pointing to a tag or commit or tree object.
 499
 500 [[def_unmerged_index]]unmerged index::
 501         An <<def_index,index>> which contains unmerged
 502         <<def_index_entry,index entries>>.
 503
 504 [[def_unreachable_object]]unreachable object::
 505         An <<def_object,object>> which is not <<def_reachable,reachable>> from a
 506         <<def_branch,branch>>, <<def_tag,tag>>, or any other reference.
 507
 508 [[def_upstream_branch]]upstream branch::
 509         The default <<def_branch,branch>> that is merged into the branch in
 510         question (or the branch in question is rebased onto). It is configured
 511         via branch.<name>.remote and branch.<name>.merge. If the upstream branch
 512         of 'A' is 'origin/B' sometimes we say "'A' is tracking 'origin/B'".
 513
 514 [[def_working_tree]]working tree::
 515         The tree of actual checked out files.  The working tree normally
 516         contains the contents of the <<def_HEAD,HEAD>> commit's tree,
 517         plus any local changes that you have made but not yet committed.