Documentation/git.txt

   1 git(1)
   2 ======
   3
   4 NAME
   5 ----
   6 git - the stupid content tracker
   7
   8
   9 SYNOPSIS
  10 --------
  11 [verse]
  12 'git' [--version] [--exec-path[=GIT_EXEC_PATH]] [--html-path]
  13     [-p|--paginate|--no-pager] [--no-replace-objects]
  14     [--bare] [--git-dir=GIT_DIR] [--work-tree=GIT_WORK_TREE]
  15     [--help] COMMAND [ARGS]
  16
  17 DESCRIPTION
  18 -----------
  19 Git is a fast, scalable, distributed revision control system with an
  20 unusually rich command set that provides both high-level operations
  21 and full access to internals.
  22
  23 See linkgit:gittutorial[7] to get started, then see
  24 link:everyday.html[Everyday Git] for a useful minimum set of commands, and
  25 "man git-commandname" for documentation of each command.  CVS users may
  26 also want to read linkgit:gitcvs-migration[7].  See
  27 the link:user-manual.html[Git User's Manual] for a more in-depth
  28 introduction.
  29
  30 The COMMAND is either a name of a Git command (see below) or an alias
  31 as defined in the configuration file (see linkgit:git-config[1]).
  32
  33 Formatted and hyperlinked version of the latest git
  34 documentation can be viewed at
  35 `http://www.kernel.org/pub/software/scm/git/docs/`.
  36
  37 ifdef::stalenotes[]
  38 [NOTE]
  39 ============
  40
  41 You are reading the documentation for the latest (possibly
  42 unreleased) version of git, that is available from 'master'
  43 branch of the `git.git` repository.
  44 Documentation for older releases are available here:
  45
  46 * link:v1.6.5.3/git.html[documentation for release 1.6.5.3]
  47
  48 * release notes for
  49   link:RelNotes-1.6.5.3.txt[1.6.5.3],
  50   link:RelNotes-1.6.5.2.txt[1.6.5.2],
  51   link:RelNotes-1.6.5.1.txt[1.6.5.1],
  52   link:RelNotes-1.6.5.txt[1.6.5].
  53
  54 * link:v1.6.4.4/git.html[documentation for release 1.6.4.4]
  55
  56 * release notes for
  57   link:RelNotes-1.6.4.4.txt[1.6.4.4],
  58   link:RelNotes-1.6.4.3.txt[1.6.4.3],
  59   link:RelNotes-1.6.4.2.txt[1.6.4.2],
  60   link:RelNotes-1.6.4.1.txt[1.6.4.1],
  61   link:RelNotes-1.6.4.txt[1.6.4].
  62
  63 * link:v1.6.3.4/git.html[documentation for release 1.6.3.4]
  64
  65 * release notes for
  66   link:RelNotes-1.6.3.4.txt[1.6.3.4],
  67   link:RelNotes-1.6.3.3.txt[1.6.3.3],
  68   link:RelNotes-1.6.3.2.txt[1.6.3.2],
  69   link:RelNotes-1.6.3.1.txt[1.6.3.1],
  70   link:RelNotes-1.6.3.txt[1.6.3].
  71
  72 * release notes for
  73   link:RelNotes-1.6.2.5.txt[1.6.2.5],
  74   link:RelNotes-1.6.2.4.txt[1.6.2.4],
  75   link:RelNotes-1.6.2.3.txt[1.6.2.3],
  76   link:RelNotes-1.6.2.2.txt[1.6.2.2],
  77   link:RelNotes-1.6.2.1.txt[1.6.2.1],
  78   link:RelNotes-1.6.2.txt[1.6.2].
  79
  80 * link:v1.6.1.3/git.html[documentation for release 1.6.1.3]
  81
  82 * release notes for
  83   link:RelNotes-1.6.1.3.txt[1.6.1.3],
  84   link:RelNotes-1.6.1.2.txt[1.6.1.2],
  85   link:RelNotes-1.6.1.1.txt[1.6.1.1],
  86   link:RelNotes-1.6.1.txt[1.6.1].
  87
  88 * link:v1.6.0.6/git.html[documentation for release 1.6.0.6]
  89
  90 * release notes for
  91   link:RelNotes-1.6.0.6.txt[1.6.0.6],
  92   link:RelNotes-1.6.0.5.txt[1.6.0.5],
  93   link:RelNotes-1.6.0.4.txt[1.6.0.4],
  94   link:RelNotes-1.6.0.3.txt[1.6.0.3],
  95   link:RelNotes-1.6.0.2.txt[1.6.0.2],
  96   link:RelNotes-1.6.0.1.txt[1.6.0.1],
  97   link:RelNotes-1.6.0.txt[1.6.0].
  98
  99 * link:v1.5.6.6/git.html[documentation for release 1.5.6.6]
 100
 101 * release notes for
 102   link:RelNotes-1.5.6.6.txt[1.5.6.6],
 103   link:RelNotes-1.5.6.5.txt[1.5.6.5],
 104   link:RelNotes-1.5.6.4.txt[1.5.6.4],
 105   link:RelNotes-1.5.6.3.txt[1.5.6.3],
 106   link:RelNotes-1.5.6.2.txt[1.5.6.2],
 107   link:RelNotes-1.5.6.1.txt[1.5.6.1],
 108   link:RelNotes-1.5.6.txt[1.5.6].
 109
 110 * link:v1.5.5.6/git.html[documentation for release 1.5.5.6]
 111
 112 * release notes for
 113   link:RelNotes-1.5.5.6.txt[1.5.5.6],
 114   link:RelNotes-1.5.5.5.txt[1.5.5.5],
 115   link:RelNotes-1.5.5.4.txt[1.5.5.4],
 116   link:RelNotes-1.5.5.3.txt[1.5.5.3],
 117   link:RelNotes-1.5.5.2.txt[1.5.5.2],
 118   link:RelNotes-1.5.5.1.txt[1.5.5.1],
 119   link:RelNotes-1.5.5.txt[1.5.5].
 120
 121 * link:v1.5.4.7/git.html[documentation for release 1.5.4.7]
 122
 123 * release notes for
 124   link:RelNotes-1.5.4.7.txt[1.5.4.7],
 125   link:RelNotes-1.5.4.6.txt[1.5.4.6],
 126   link:RelNotes-1.5.4.5.txt[1.5.4.5],
 127   link:RelNotes-1.5.4.4.txt[1.5.4.4],
 128   link:RelNotes-1.5.4.3.txt[1.5.4.3],
 129   link:RelNotes-1.5.4.2.txt[1.5.4.2],
 130   link:RelNotes-1.5.4.1.txt[1.5.4.1],
 131   link:RelNotes-1.5.4.txt[1.5.4].
 132
 133 * link:v1.5.3.8/git.html[documentation for release 1.5.3.8]
 134
 135 * release notes for
 136   link:RelNotes-1.5.3.8.txt[1.5.3.8],
 137   link:RelNotes-1.5.3.7.txt[1.5.3.7],
 138   link:RelNotes-1.5.3.6.txt[1.5.3.6],
 139   link:RelNotes-1.5.3.5.txt[1.5.3.5],
 140   link:RelNotes-1.5.3.4.txt[1.5.3.4],
 141   link:RelNotes-1.5.3.3.txt[1.5.3.3],
 142   link:RelNotes-1.5.3.2.txt[1.5.3.2],
 143   link:RelNotes-1.5.3.1.txt[1.5.3.1],
 144   link:RelNotes-1.5.3.txt[1.5.3].
 145
 146 * link:v1.5.2.5/git.html[documentation for release 1.5.2.5]
 147
 148 * release notes for
 149   link:RelNotes-1.5.2.5.txt[1.5.2.5],
 150   link:RelNotes-1.5.2.4.txt[1.5.2.4],
 151   link:RelNotes-1.5.2.3.txt[1.5.2.3],
 152   link:RelNotes-1.5.2.2.txt[1.5.2.2],
 153   link:RelNotes-1.5.2.1.txt[1.5.2.1],
 154   link:RelNotes-1.5.2.txt[1.5.2].
 155
 156 * link:v1.5.1.6/git.html[documentation for release 1.5.1.6]
 157
 158 * release notes for
 159   link:RelNotes-1.5.1.6.txt[1.5.1.6],
 160   link:RelNotes-1.5.1.5.txt[1.5.1.5],
 161   link:RelNotes-1.5.1.4.txt[1.5.1.4],
 162   link:RelNotes-1.5.1.3.txt[1.5.1.3],
 163   link:RelNotes-1.5.1.2.txt[1.5.1.2],
 164   link:RelNotes-1.5.1.1.txt[1.5.1.1],
 165   link:RelNotes-1.5.1.txt[1.5.1].
 166
 167 * link:v1.5.0.7/git.html[documentation for release 1.5.0.7]
 168
 169 * release notes for
 170   link:RelNotes-1.5.0.7.txt[1.5.0.7],
 171   link:RelNotes-1.5.0.6.txt[1.5.0.6],
 172   link:RelNotes-1.5.0.5.txt[1.5.0.5],
 173   link:RelNotes-1.5.0.3.txt[1.5.0.3],
 174   link:RelNotes-1.5.0.2.txt[1.5.0.2],
 175   link:RelNotes-1.5.0.1.txt[1.5.0.1],
 176   link:RelNotes-1.5.0.txt[1.5.0].
 177
 178 * documentation for release link:v1.4.4.4/git.html[1.4.4.4],
 179   link:v1.3.3/git.html[1.3.3],
 180   link:v1.2.6/git.html[1.2.6],
 181   link:v1.0.13/git.html[1.0.13].
 182
 183 ============
 184
 185 endif::stalenotes[]
 186
 187 OPTIONS
 188 -------
 189 --version::
 190         Prints the git suite version that the 'git' program came from.
 191
 192 --help::
 193         Prints the synopsis and a list of the most commonly used
 194         commands. If the option '--all' or '-a' is given then all
 195         available commands are printed. If a git command is named this
 196         option will bring up the manual page for that command.
 197 +
 198 Other options are available to control how the manual page is
 199 displayed. See linkgit:git-help[1] for more information,
 200 because `git --help ...` is converted internally into `git
 201 help ...`.
 202
 203 --exec-path::
 204         Path to wherever your core git programs are installed.
 205         This can also be controlled by setting the GIT_EXEC_PATH
 206         environment variable. If no path is given, 'git' will print
 207         the current setting and then exit.
 208
 209 --html-path::
 210         Print the path to wherever your git HTML documentation is installed
 211         and exit.
 212
 213 -p::
 214 --paginate::
 215         Pipe all output into 'less' (or if set, $PAGER).
 216
 217 --no-pager::
 218         Do not pipe git output into a pager.
 219
 220 --git-dir=<path>::
 221         Set the path to the repository. This can also be controlled by
 222         setting the GIT_DIR environment variable. It can be an absolute
 223         path or relative path to current working directory.
 224
 225 --work-tree=<path>::
 226         Set the path to the working tree.  The value will not be
 227         used in combination with repositories found automatically in
 228         a .git directory (i.e. $GIT_DIR is not set).
 229         This can also be controlled by setting the GIT_WORK_TREE
 230         environment variable and the core.worktree configuration
 231         variable. It can be an absolute path or relative path to
 232         the directory specified by --git-dir or GIT_DIR.
 233         Note: If --git-dir or GIT_DIR are specified but none of
 234         --work-tree, GIT_WORK_TREE and core.worktree is specified,
 235         the current working directory is regarded as the top directory
 236         of your working tree.
 237
 238 --bare::
 239         Treat the repository as a bare repository.  If GIT_DIR
 240         environment is not set, it is set to the current working
 241         directory.
 242
 243 --no-replace-objects::
 244         Do not use replacement refs to replace git objects. See
 245         linkgit:git-replace[1] for more information.
 246
 247
 248 FURTHER DOCUMENTATION
 249 ---------------------
 250
 251 See the references above to get started using git.  The following is
 252 probably more detail than necessary for a first-time user.
 253
 254 The link:user-manual.html#git-concepts[git concepts chapter of the
 255 user-manual] and linkgit:gitcore-tutorial[7] both provide
 256 introductions to the underlying git architecture.
 257
 258 See linkgit:gitworkflows[7] for an overview of recommended workflows.
 259
 260 See also the link:howto-index.html[howto] documents for some useful
 261 examples.
 262
 263 The internals are documented in the
 264 link:technical/api-index.html[GIT API documentation].
 265
 266 GIT COMMANDS
 267 ------------
 268
 269 We divide git into high level ("porcelain") commands and low level
 270 ("plumbing") commands.
 271
 272 High-level commands (porcelain)
 273 -------------------------------
 274
 275 We separate the porcelain commands into the main commands and some
 276 ancillary user utilities.
 277
 278 Main porcelain commands
 279 ~~~~~~~~~~~~~~~~~~~~~~~
 280
 281 include::cmds-mainporcelain.txt[]
 282
 283 Ancillary Commands
 284 ~~~~~~~~~~~~~~~~~~
 285 Manipulators:
 286
 287 include::cmds-ancillarymanipulators.txt[]
 288
 289 Interrogators:
 290
 291 include::cmds-ancillaryinterrogators.txt[]
 292
 293
 294 Interacting with Others
 295 ~~~~~~~~~~~~~~~~~~~~~~~
 296
 297 These commands are to interact with foreign SCM and with other
 298 people via patch over e-mail.
 299
 300 include::cmds-foreignscminterface.txt[]
 301
 302
 303 Low-level commands (plumbing)
 304 -----------------------------
 305
 306 Although git includes its
 307 own porcelain layer, its low-level commands are sufficient to support
 308 development of alternative porcelains.  Developers of such porcelains
 309 might start by reading about linkgit:git-update-index[1] and
 310 linkgit:git-read-tree[1].
 311
 312 The interface (input, output, set of options and the semantics)
 313 to these low-level commands are meant to be a lot more stable
 314 than Porcelain level commands, because these commands are
 315 primarily for scripted use.  The interface to Porcelain commands
 316 on the other hand are subject to change in order to improve the
 317 end user experience.
 318
 319 The following description divides
 320 the low-level commands into commands that manipulate objects (in
 321 the repository, index, and working tree), commands that interrogate and
 322 compare objects, and commands that move objects and references between
 323 repositories.
 324
 325
 326 Manipulation commands
 327 ~~~~~~~~~~~~~~~~~~~~~
 328
 329 include::cmds-plumbingmanipulators.txt[]
 330
 331
 332 Interrogation commands
 333 ~~~~~~~~~~~~~~~~~~~~~~
 334
 335 include::cmds-plumbinginterrogators.txt[]
 336
 337 In general, the interrogate commands do not touch the files in
 338 the working tree.
 339
 340
 341 Synching repositories
 342 ~~~~~~~~~~~~~~~~~~~~~
 343
 344 include::cmds-synchingrepositories.txt[]
 345
 346 The following are helper commands used by the above; end users
 347 typically do not use them directly.
 348
 349 include::cmds-synchelpers.txt[]
 350
 351
 352 Internal helper commands
 353 ~~~~~~~~~~~~~~~~~~~~~~~~
 354
 355 These are internal helper commands used by other commands; end
 356 users typically do not use them directly.
 357
 358 include::cmds-purehelpers.txt[]
 359
 360
 361 Configuration Mechanism
 362 -----------------------
 363
 364 Starting from 0.99.9 (actually mid 0.99.8.GIT), `.git/config` file
 365 is used to hold per-repository configuration options.  It is a
 366 simple text file modeled after `.ini` format familiar to some
 367 people.  Here is an example:
 368
 369 ------------
 370 #
 371 # A '#' or ';' character indicates a comment.
 372 #
 373
 374 ; core variables
 375 [core]
 376         ; Don't trust file modes
 377         filemode = false
 378
 379 ; user identity
 380 [user]
 381         name = "Junio C Hamano"
 382         email = "junkio@twinsun.com"
 383
 384 ------------
 385
 386 Various commands read from the configuration file and adjust
 387 their operation accordingly.
 388
 389
 390 Identifier Terminology
 391 ----------------------
 392 <object>::
 393         Indicates the object name for any type of object.
 394
 395 <blob>::
 396         Indicates a blob object name.
 397
 398 <tree>::
 399         Indicates a tree object name.
 400
 401 <commit>::
 402         Indicates a commit object name.
 403
 404 <tree-ish>::
 405         Indicates a tree, commit or tag object name.  A
 406         command that takes a <tree-ish> argument ultimately wants to
 407         operate on a <tree> object but automatically dereferences
 408         <commit> and <tag> objects that point at a <tree>.
 409
 410 <commit-ish>::
 411         Indicates a commit or tag object name.  A
 412         command that takes a <commit-ish> argument ultimately wants to
 413         operate on a <commit> object but automatically dereferences
 414         <tag> objects that point at a <commit>.
 415
 416 <type>::
 417         Indicates that an object type is required.
 418         Currently one of: `blob`, `tree`, `commit`, or `tag`.
 419
 420 <file>::
 421         Indicates a filename - almost always relative to the
 422         root of the tree structure `GIT_INDEX_FILE` describes.
 423
 424 Symbolic Identifiers
 425 --------------------
 426 Any git command accepting any <object> can also use the following
 427 symbolic notation:
 428
 429 HEAD::
 430         indicates the head of the current branch (i.e. the
 431         contents of `$GIT_DIR/HEAD`).
 432
 433 <tag>::
 434         a valid tag 'name'
 435         (i.e. the contents of `$GIT_DIR/refs/tags/<tag>`).
 436
 437 <head>::
 438         a valid head 'name'
 439         (i.e. the contents of `$GIT_DIR/refs/heads/<head>`).
 440
 441 For a more complete list of ways to spell object names, see
 442 "SPECIFYING REVISIONS" section in linkgit:git-rev-parse[1].
 443
 444
 445 File/Directory Structure
 446 ------------------------
 447
 448 Please see the linkgit:gitrepository-layout[5] document.
 449
 450 Read linkgit:githooks[5] for more details about each hook.
 451
 452 Higher level SCMs may provide and manage additional information in the
 453 `$GIT_DIR`.
 454
 455
 456 Terminology
 457 -----------
 458 Please see linkgit:gitglossary[7].
 459
 460
 461 Environment Variables
 462 ---------------------
 463 Various git commands use the following environment variables:
 464
 465 The git Repository
 466 ~~~~~~~~~~~~~~~~~~
 467 These environment variables apply to 'all' core git commands. Nb: it
 468 is worth noting that they may be used/overridden by SCMS sitting above
 469 git so take care if using Cogito etc.
 470
 471 'GIT_INDEX_FILE'::
 472         This environment allows the specification of an alternate
 473         index file. If not specified, the default of `$GIT_DIR/index`
 474         is used.
 475
 476 'GIT_OBJECT_DIRECTORY'::
 477         If the object storage directory is specified via this
 478         environment variable then the sha1 directories are created
 479         underneath - otherwise the default `$GIT_DIR/objects`
 480         directory is used.
 481
 482 'GIT_ALTERNATE_OBJECT_DIRECTORIES'::
 483         Due to the immutable nature of git objects, old objects can be
 484         archived into shared, read-only directories. This variable
 485         specifies a ":" separated (on Windows ";" separated) list
 486         of git object directories which can be used to search for git
 487         objects. New objects will not be written to these directories.
 488
 489 'GIT_DIR'::
 490         If the 'GIT_DIR' environment variable is set then it
 491         specifies a path to use instead of the default `.git`
 492         for the base of the repository.
 493
 494 'GIT_WORK_TREE'::
 495         Set the path to the working tree.  The value will not be
 496         used in combination with repositories found automatically in
 497         a .git directory (i.e. $GIT_DIR is not set).
 498         This can also be controlled by the '--work-tree' command line
 499         option and the core.worktree configuration variable.
 500
 501 'GIT_CEILING_DIRECTORIES'::
 502         This should be a colon-separated list of absolute paths.
 503         If set, it is a list of directories that git should not chdir
 504         up into while looking for a repository directory.
 505         It will not exclude the current working directory or
 506         a GIT_DIR set on the command line or in the environment.
 507         (Useful for excluding slow-loading network directories.)
 508
 509 git Commits
 510 ~~~~~~~~~~~
 511 'GIT_AUTHOR_NAME'::
 512 'GIT_AUTHOR_EMAIL'::
 513 'GIT_AUTHOR_DATE'::
 514 'GIT_COMMITTER_NAME'::
 515 'GIT_COMMITTER_EMAIL'::
 516 'GIT_COMMITTER_DATE'::
 517 'EMAIL'::
 518         see linkgit:git-commit-tree[1]
 519
 520 git Diffs
 521 ~~~~~~~~~
 522 'GIT_DIFF_OPTS'::
 523         Only valid setting is "--unified=??" or "-u??" to set the
 524         number of context lines shown when a unified diff is created.
 525         This takes precedence over any "-U" or "--unified" option
 526         value passed on the git diff command line.
 527
 528 'GIT_EXTERNAL_DIFF'::
 529         When the environment variable 'GIT_EXTERNAL_DIFF' is set, the
 530         program named by it is called, instead of the diff invocation
 531         described above.  For a path that is added, removed, or modified,
 532         'GIT_EXTERNAL_DIFF' is called with 7 parameters:
 533
 534         path old-file old-hex old-mode new-file new-hex new-mode
 535 +
 536 where:
 537
 538         <old|new>-file:: are files GIT_EXTERNAL_DIFF can use to read the
 539                          contents of <old|new>,
 540         <old|new>-hex:: are the 40-hexdigit SHA1 hashes,
 541         <old|new>-mode:: are the octal representation of the file modes.
 542
 543 +
 544 The file parameters can point at the user's working file
 545 (e.g. `new-file` in "git-diff-files"), `/dev/null` (e.g. `old-file`
 546 when a new file is added), or a temporary file (e.g. `old-file` in the
 547 index).  'GIT_EXTERNAL_DIFF' should not worry about unlinking the
 548 temporary file --- it is removed when 'GIT_EXTERNAL_DIFF' exits.
 549 +
 550 For a path that is unmerged, 'GIT_EXTERNAL_DIFF' is called with 1
 551 parameter, <path>.
 552
 553 other
 554 ~~~~~
 555 'GIT_MERGE_VERBOSITY'::
 556         A number controlling the amount of output shown by
 557         the recursive merge strategy.  Overrides merge.verbosity.
 558         See linkgit:git-merge[1]
 559
 560 'GIT_PAGER'::
 561         This environment variable overrides `$PAGER`. If it is set
 562         to an empty string or to the value "cat", git will not launch
 563         a pager.  See also the `core.pager` option in
 564         linkgit:git-config[1].
 565
 566 'GIT_SSH'::
 567         If this environment variable is set then 'git-fetch'
 568         and 'git-push' will use this command instead
 569         of 'ssh' when they need to connect to a remote system.
 570         The '$GIT_SSH' command will be given exactly two arguments:
 571         the 'username@host' (or just 'host') from the URL and the
 572         shell command to execute on that remote system.
 573 +
 574 To pass options to the program that you want to list in GIT_SSH
 575 you will need to wrap the program and options into a shell script,
 576 then set GIT_SSH to refer to the shell script.
 577 +
 578 Usually it is easier to configure any desired options through your
 579 personal `.ssh/config` file.  Please consult your ssh documentation
 580 for further details.
 581
 582 'GIT_FLUSH'::
 583         If this environment variable is set to "1", then commands such
 584         as 'git-blame' (in incremental mode), 'git-rev-list', 'git-log',
 585         and 'git-whatchanged' will force a flush of the output stream
 586         after each commit-oriented record have been flushed.   If this
 587         variable is set to "0", the output of these commands will be done
 588         using completely buffered I/O.   If this environment variable is
 589         not set, git will choose buffered or record-oriented flushing
 590         based on whether stdout appears to be redirected to a file or not.
 591
 592 'GIT_TRACE'::
 593         If this variable is set to "1", "2" or "true" (comparison
 594         is case insensitive), git will print `trace:` messages on
 595         stderr telling about alias expansion, built-in command
 596         execution and external command execution.
 597         If this variable is set to an integer value greater than 1
 598         and lower than 10 (strictly) then git will interpret this
 599         value as an open file descriptor and will try to write the
 600         trace messages into this file descriptor.
 601         Alternatively, if this variable is set to an absolute path
 602         (starting with a '/' character), git will interpret this
 603         as a file path and will try to write the trace messages
 604         into it.
 605
 606 Discussion[[Discussion]]
 607 ------------------------
 608
 609 More detail on the following is available from the
 610 link:user-manual.html#git-concepts[git concepts chapter of the
 611 user-manual] and linkgit:gitcore-tutorial[7].
 612
 613 A git project normally consists of a working directory with a ".git"
 614 subdirectory at the top level.  The .git directory contains, among other
 615 things, a compressed object database representing the complete history
 616 of the project, an "index" file which links that history to the current
 617 contents of the working tree, and named pointers into that history such
 618 as tags and branch heads.
 619
 620 The object database contains objects of three main types: blobs, which
 621 hold file data; trees, which point to blobs and other trees to build up
 622 directory hierarchies; and commits, which each reference a single tree
 623 and some number of parent commits.
 624
 625 The commit, equivalent to what other systems call a "changeset" or
 626 "version", represents a step in the project's history, and each parent
 627 represents an immediately preceding step.  Commits with more than one
 628 parent represent merges of independent lines of development.
 629
 630 All objects are named by the SHA1 hash of their contents, normally
 631 written as a string of 40 hex digits.  Such names are globally unique.
 632 The entire history leading up to a commit can be vouched for by signing
 633 just that commit.  A fourth object type, the tag, is provided for this
 634 purpose.
 635
 636 When first created, objects are stored in individual files, but for
 637 efficiency may later be compressed together into "pack files".
 638
 639 Named pointers called refs mark interesting points in history.  A ref
 640 may contain the SHA1 name of an object or the name of another ref.  Refs
 641 with names beginning `ref/head/` contain the SHA1 name of the most
 642 recent commit (or "head") of a branch under development.  SHA1 names of
 643 tags of interest are stored under `ref/tags/`.  A special ref named
 644 `HEAD` contains the name of the currently checked-out branch.
 645
 646 The index file is initialized with a list of all paths and, for each
 647 path, a blob object and a set of attributes.  The blob object represents
 648 the contents of the file as of the head of the current branch.  The
 649 attributes (last modified time, size, etc.) are taken from the
 650 corresponding file in the working tree.  Subsequent changes to the
 651 working tree can be found by comparing these attributes.  The index may
 652 be updated with new content, and new commits may be created from the
 653 content stored in the index.
 654
 655 The index is also capable of storing multiple entries (called "stages")
 656 for a given pathname.  These stages are used to hold the various
 657 unmerged version of a file when a merge is in progress.
 658
 659 Authors
 660 -------
 661 * git's founding father is Linus Torvalds <torvalds@osdl.org>.
 662 * The current git nurse is Junio C Hamano <gitster@pobox.com>.
 663 * The git potty was written by Andreas Ericsson <ae@op5.se>.
 664 * General upbringing is handled by the git-list <git@vger.kernel.org>.
 665
 666 Documentation
 667 --------------
 668 The documentation for git suite was started by David Greaves
 669 <david@dgreaves.com>, and later enhanced greatly by the
 670 contributors on the git-list <git@vger.kernel.org>.
 671
 672 SEE ALSO
 673 --------
 674 linkgit:gittutorial[7], linkgit:gittutorial-2[7],
 675 link:everyday.html[Everyday Git], linkgit:gitcvs-migration[7],
 676 linkgit:gitglossary[7], linkgit:gitcore-tutorial[7],
 677 linkgit:gitcli[7], link:user-manual.html[The Git User's Manual],
 678 linkgit:gitworkflows[7]
 679
 680 GIT
 681 ---
 682 Part of the linkgit:git[1] suite