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[=<path>]] [--html-path]
  13     [-p|--paginate|--no-pager] [--no-replace-objects]
  14     [--bare] [--git-dir=<path>] [--work-tree=<path>]
  15     [-c <name>=<value>]
  16     [--help] <command> [<args>]
  17
  18 DESCRIPTION
  19 -----------
  20 Git is a fast, scalable, distributed revision control system with an
  21 unusually rich command set that provides both high-level operations
  22 and full access to internals.
  23
  24 See linkgit:gittutorial[7] to get started, then see
  25 link:everyday.html[Everyday Git] for a useful minimum set of commands, and
  26 "man git-commandname" for documentation of each command.  CVS users may
  27 also want to read linkgit:gitcvs-migration[7].  See
  28 the link:user-manual.html[Git User's Manual] for a more in-depth
  29 introduction.
  30
  31 The '<command>' is either a name of a Git command (see below) or an alias
  32 as defined in the configuration file (see linkgit:git-config[1]).
  33
  34 Formatted and hyperlinked version of the latest git
  35 documentation can be viewed at
  36 `http://www.kernel.org/pub/software/scm/git/docs/`.
  37
  38 ifdef::stalenotes[]
  39 [NOTE]
  40 ============
  41
  42 You are reading the documentation for the latest (possibly
  43 unreleased) version of git, that is available from 'master'
  44 branch of the `git.git` repository.
  45 Documentation for older releases are available here:
  46
  47 * link:v1.7.3.4/git.html[documentation for release 1.7.3.4]
  48
  49 * release notes for
  50   link:RelNotes/1.7.3.4.txt[1.7.3.4],
  51   link:RelNotes/1.7.3.3.txt[1.7.3.3],
  52   link:RelNotes/1.7.3.2.txt[1.7.3.2],
  53   link:RelNotes/1.7.3.1.txt[1.7.3.1],
  54   link:RelNotes/1.7.3.txt[1.7.3].
  55
  56 * link:v1.7.2.5/git.html[documentation for release 1.7.2.5]
  57
  58 * release notes for
  59   link:RelNotes/1.7.2.5.txt[1.7.2.5],
  60   link:RelNotes/1.7.2.4.txt[1.7.2.4],
  61   link:RelNotes/1.7.2.3.txt[1.7.2.3],
  62   link:RelNotes/1.7.2.2.txt[1.7.2.2],
  63   link:RelNotes/1.7.2.1.txt[1.7.2.1],
  64   link:RelNotes/1.7.2.txt[1.7.2].
  65
  66 * link:v1.7.1.4/git.html[documentation for release 1.7.1.4]
  67
  68 * release notes for
  69   link:RelNotes/1.7.1.4.txt[1.7.1.4],
  70   link:RelNotes/1.7.1.3.txt[1.7.1.3],
  71   link:RelNotes/1.7.1.2.txt[1.7.1.2],
  72   link:RelNotes/1.7.1.1.txt[1.7.1.1],
  73   link:RelNotes/1.7.1.txt[1.7.1].
  74
  75 * link:v1.7.0.9/git.html[documentation for release 1.7.0.9]
  76
  77 * release notes for
  78   link:RelNotes/1.7.0.9.txt[1.7.0.9],
  79   link:RelNotes/1.7.0.8.txt[1.7.0.8],
  80   link:RelNotes/1.7.0.7.txt[1.7.0.7],
  81   link:RelNotes/1.7.0.6.txt[1.7.0.6],
  82   link:RelNotes/1.7.0.5.txt[1.7.0.5],
  83   link:RelNotes/1.7.0.4.txt[1.7.0.4],
  84   link:RelNotes/1.7.0.3.txt[1.7.0.3],
  85   link:RelNotes/1.7.0.2.txt[1.7.0.2],
  86   link:RelNotes/1.7.0.1.txt[1.7.0.1],
  87   link:RelNotes/1.7.0.txt[1.7.0].
  88
  89 * link:v1.6.6.3/git.html[documentation for release 1.6.6.3]
  90
  91 * release notes for
  92   link:RelNotes/1.6.6.3.txt[1.6.6.3],
  93   link:RelNotes/1.6.6.2.txt[1.6.6.2],
  94   link:RelNotes/1.6.6.1.txt[1.6.6.1],
  95   link:RelNotes/1.6.6.txt[1.6.6].
  96
  97 * link:v1.6.5.9/git.html[documentation for release 1.6.5.9]
  98
  99 * release notes for
 100   link:RelNotes/1.6.5.9.txt[1.6.5.9],
 101   link:RelNotes/1.6.5.8.txt[1.6.5.8],
 102   link:RelNotes/1.6.5.7.txt[1.6.5.7],
 103   link:RelNotes/1.6.5.6.txt[1.6.5.6],
 104   link:RelNotes/1.6.5.5.txt[1.6.5.5],
 105   link:RelNotes/1.6.5.4.txt[1.6.5.4],
 106   link:RelNotes/1.6.5.3.txt[1.6.5.3],
 107   link:RelNotes/1.6.5.2.txt[1.6.5.2],
 108   link:RelNotes/1.6.5.1.txt[1.6.5.1],
 109   link:RelNotes/1.6.5.txt[1.6.5].
 110
 111 * link:v1.6.4.5/git.html[documentation for release 1.6.4.5]
 112
 113 * release notes for
 114   link:RelNotes/1.6.4.5.txt[1.6.4.5],
 115   link:RelNotes/1.6.4.4.txt[1.6.4.4],
 116   link:RelNotes/1.6.4.3.txt[1.6.4.3],
 117   link:RelNotes/1.6.4.2.txt[1.6.4.2],
 118   link:RelNotes/1.6.4.1.txt[1.6.4.1],
 119   link:RelNotes/1.6.4.txt[1.6.4].
 120
 121 * link:v1.6.3.4/git.html[documentation for release 1.6.3.4]
 122
 123 * release notes for
 124   link:RelNotes/1.6.3.4.txt[1.6.3.4],
 125   link:RelNotes/1.6.3.3.txt[1.6.3.3],
 126   link:RelNotes/1.6.3.2.txt[1.6.3.2],
 127   link:RelNotes/1.6.3.1.txt[1.6.3.1],
 128   link:RelNotes/1.6.3.txt[1.6.3].
 129
 130 * release notes for
 131   link:RelNotes/1.6.2.5.txt[1.6.2.5],
 132   link:RelNotes/1.6.2.4.txt[1.6.2.4],
 133   link:RelNotes/1.6.2.3.txt[1.6.2.3],
 134   link:RelNotes/1.6.2.2.txt[1.6.2.2],
 135   link:RelNotes/1.6.2.1.txt[1.6.2.1],
 136   link:RelNotes/1.6.2.txt[1.6.2].
 137
 138 * link:v1.6.1.3/git.html[documentation for release 1.6.1.3]
 139
 140 * release notes for
 141   link:RelNotes/1.6.1.3.txt[1.6.1.3],
 142   link:RelNotes/1.6.1.2.txt[1.6.1.2],
 143   link:RelNotes/1.6.1.1.txt[1.6.1.1],
 144   link:RelNotes/1.6.1.txt[1.6.1].
 145
 146 * link:v1.6.0.6/git.html[documentation for release 1.6.0.6]
 147
 148 * release notes for
 149   link:RelNotes/1.6.0.6.txt[1.6.0.6],
 150   link:RelNotes/1.6.0.5.txt[1.6.0.5],
 151   link:RelNotes/1.6.0.4.txt[1.6.0.4],
 152   link:RelNotes/1.6.0.3.txt[1.6.0.3],
 153   link:RelNotes/1.6.0.2.txt[1.6.0.2],
 154   link:RelNotes/1.6.0.1.txt[1.6.0.1],
 155   link:RelNotes/1.6.0.txt[1.6.0].
 156
 157 * link:v1.5.6.6/git.html[documentation for release 1.5.6.6]
 158
 159 * release notes for
 160   link:RelNotes/1.5.6.6.txt[1.5.6.6],
 161   link:RelNotes/1.5.6.5.txt[1.5.6.5],
 162   link:RelNotes/1.5.6.4.txt[1.5.6.4],
 163   link:RelNotes/1.5.6.3.txt[1.5.6.3],
 164   link:RelNotes/1.5.6.2.txt[1.5.6.2],
 165   link:RelNotes/1.5.6.1.txt[1.5.6.1],
 166   link:RelNotes/1.5.6.txt[1.5.6].
 167
 168 * link:v1.5.5.6/git.html[documentation for release 1.5.5.6]
 169
 170 * release notes for
 171   link:RelNotes/1.5.5.6.txt[1.5.5.6],
 172   link:RelNotes/1.5.5.5.txt[1.5.5.5],
 173   link:RelNotes/1.5.5.4.txt[1.5.5.4],
 174   link:RelNotes/1.5.5.3.txt[1.5.5.3],
 175   link:RelNotes/1.5.5.2.txt[1.5.5.2],
 176   link:RelNotes/1.5.5.1.txt[1.5.5.1],
 177   link:RelNotes/1.5.5.txt[1.5.5].
 178
 179 * link:v1.5.4.7/git.html[documentation for release 1.5.4.7]
 180
 181 * release notes for
 182   link:RelNotes/1.5.4.7.txt[1.5.4.7],
 183   link:RelNotes/1.5.4.6.txt[1.5.4.6],
 184   link:RelNotes/1.5.4.5.txt[1.5.4.5],
 185   link:RelNotes/1.5.4.4.txt[1.5.4.4],
 186   link:RelNotes/1.5.4.3.txt[1.5.4.3],
 187   link:RelNotes/1.5.4.2.txt[1.5.4.2],
 188   link:RelNotes/1.5.4.1.txt[1.5.4.1],
 189   link:RelNotes/1.5.4.txt[1.5.4].
 190
 191 * link:v1.5.3.8/git.html[documentation for release 1.5.3.8]
 192
 193 * release notes for
 194   link:RelNotes/1.5.3.8.txt[1.5.3.8],
 195   link:RelNotes/1.5.3.7.txt[1.5.3.7],
 196   link:RelNotes/1.5.3.6.txt[1.5.3.6],
 197   link:RelNotes/1.5.3.5.txt[1.5.3.5],
 198   link:RelNotes/1.5.3.4.txt[1.5.3.4],
 199   link:RelNotes/1.5.3.3.txt[1.5.3.3],
 200   link:RelNotes/1.5.3.2.txt[1.5.3.2],
 201   link:RelNotes/1.5.3.1.txt[1.5.3.1],
 202   link:RelNotes/1.5.3.txt[1.5.3].
 203
 204 * link:v1.5.2.5/git.html[documentation for release 1.5.2.5]
 205
 206 * release notes for
 207   link:RelNotes/1.5.2.5.txt[1.5.2.5],
 208   link:RelNotes/1.5.2.4.txt[1.5.2.4],
 209   link:RelNotes/1.5.2.3.txt[1.5.2.3],
 210   link:RelNotes/1.5.2.2.txt[1.5.2.2],
 211   link:RelNotes/1.5.2.1.txt[1.5.2.1],
 212   link:RelNotes/1.5.2.txt[1.5.2].
 213
 214 * link:v1.5.1.6/git.html[documentation for release 1.5.1.6]
 215
 216 * release notes for
 217   link:RelNotes/1.5.1.6.txt[1.5.1.6],
 218   link:RelNotes/1.5.1.5.txt[1.5.1.5],
 219   link:RelNotes/1.5.1.4.txt[1.5.1.4],
 220   link:RelNotes/1.5.1.3.txt[1.5.1.3],
 221   link:RelNotes/1.5.1.2.txt[1.5.1.2],
 222   link:RelNotes/1.5.1.1.txt[1.5.1.1],
 223   link:RelNotes/1.5.1.txt[1.5.1].
 224
 225 * link:v1.5.0.7/git.html[documentation for release 1.5.0.7]
 226
 227 * release notes for
 228   link:RelNotes/1.5.0.7.txt[1.5.0.7],
 229   link:RelNotes/1.5.0.6.txt[1.5.0.6],
 230   link:RelNotes/1.5.0.5.txt[1.5.0.5],
 231   link:RelNotes/1.5.0.3.txt[1.5.0.3],
 232   link:RelNotes/1.5.0.2.txt[1.5.0.2],
 233   link:RelNotes/1.5.0.1.txt[1.5.0.1],
 234   link:RelNotes/1.5.0.txt[1.5.0].
 235
 236 * documentation for release link:v1.4.4.4/git.html[1.4.4.4],
 237   link:v1.3.3/git.html[1.3.3],
 238   link:v1.2.6/git.html[1.2.6],
 239   link:v1.0.13/git.html[1.0.13].
 240
 241 ============
 242
 243 endif::stalenotes[]
 244
 245 OPTIONS
 246 -------
 247 --version::
 248         Prints the git suite version that the 'git' program came from.
 249
 250 --help::
 251         Prints the synopsis and a list of the most commonly used
 252         commands. If the option '--all' or '-a' is given then all
 253         available commands are printed. If a git command is named this
 254         option will bring up the manual page for that command.
 255 +
 256 Other options are available to control how the manual page is
 257 displayed. See linkgit:git-help[1] for more information,
 258 because `git --help ...` is converted internally into `git
 259 help ...`.
 260
 261 -c <name>=<value>::
 262         Pass a configuration parameter to the command. The value
 263         given will override values from configuration files.
 264         The <name> is expected in the same format as listed by
 265         'git config' (subkeys separated by dots).
 266
 267 --exec-path[=<path>]::
 268         Path to wherever your core git programs are installed.
 269         This can also be controlled by setting the GIT_EXEC_PATH
 270         environment variable. If no path is given, 'git' will print
 271         the current setting and then exit.
 272
 273 --html-path::
 274         Print the path to wherever your git HTML documentation is installed
 275         and exit.
 276
 277 -p::
 278 --paginate::
 279         Pipe all output into 'less' (or if set, $PAGER) if standard
 280         output is a terminal.  This overrides the `pager.<cmd>`
 281         configuration options (see the "Configuration Mechanism" section
 282         below).
 283
 284 --no-pager::
 285         Do not pipe git output into a pager.
 286
 287 --git-dir=<path>::
 288         Set the path to the repository. This can also be controlled by
 289         setting the GIT_DIR environment variable. It can be an absolute
 290         path or relative path to current working directory.
 291
 292 --work-tree=<path>::
 293         Set the path to the working tree.  The value will not be
 294         used in combination with repositories found automatically in
 295         a .git directory (i.e. $GIT_DIR is not set).
 296         This can also be controlled by setting the GIT_WORK_TREE
 297         environment variable and the core.worktree configuration
 298         variable. It can be an absolute path or relative path to
 299         the directory specified by --git-dir or GIT_DIR.
 300         Note: If --git-dir or GIT_DIR are specified but none of
 301         --work-tree, GIT_WORK_TREE and core.worktree is specified,
 302         the current working directory is regarded as the top directory
 303         of your working tree.
 304
 305 --bare::
 306         Treat the repository as a bare repository.  If GIT_DIR
 307         environment is not set, it is set to the current working
 308         directory.
 309
 310 --no-replace-objects::
 311         Do not use replacement refs to replace git objects. See
 312         linkgit:git-replace[1] for more information.
 313
 314
 315 FURTHER DOCUMENTATION
 316 ---------------------
 317
 318 See the references above to get started using git.  The following is
 319 probably more detail than necessary for a first-time user.
 320
 321 The link:user-manual.html#git-concepts[git concepts chapter of the
 322 user-manual] and linkgit:gitcore-tutorial[7] both provide
 323 introductions to the underlying git architecture.
 324
 325 See linkgit:gitworkflows[7] for an overview of recommended workflows.
 326
 327 See also the link:howto-index.html[howto] documents for some useful
 328 examples.
 329
 330 The internals are documented in the
 331 link:technical/api-index.html[GIT API documentation].
 332
 333 GIT COMMANDS
 334 ------------
 335
 336 We divide git into high level ("porcelain") commands and low level
 337 ("plumbing") commands.
 338
 339 High-level commands (porcelain)
 340 -------------------------------
 341
 342 We separate the porcelain commands into the main commands and some
 343 ancillary user utilities.
 344
 345 Main porcelain commands
 346 ~~~~~~~~~~~~~~~~~~~~~~~
 347
 348 include::cmds-mainporcelain.txt[]
 349
 350 Ancillary Commands
 351 ~~~~~~~~~~~~~~~~~~
 352 Manipulators:
 353
 354 include::cmds-ancillarymanipulators.txt[]
 355
 356 Interrogators:
 357
 358 include::cmds-ancillaryinterrogators.txt[]
 359
 360
 361 Interacting with Others
 362 ~~~~~~~~~~~~~~~~~~~~~~~
 363
 364 These commands are to interact with foreign SCM and with other
 365 people via patch over e-mail.
 366
 367 include::cmds-foreignscminterface.txt[]
 368
 369
 370 Low-level commands (plumbing)
 371 -----------------------------
 372
 373 Although git includes its
 374 own porcelain layer, its low-level commands are sufficient to support
 375 development of alternative porcelains.  Developers of such porcelains
 376 might start by reading about linkgit:git-update-index[1] and
 377 linkgit:git-read-tree[1].
 378
 379 The interface (input, output, set of options and the semantics)
 380 to these low-level commands are meant to be a lot more stable
 381 than Porcelain level commands, because these commands are
 382 primarily for scripted use.  The interface to Porcelain commands
 383 on the other hand are subject to change in order to improve the
 384 end user experience.
 385
 386 The following description divides
 387 the low-level commands into commands that manipulate objects (in
 388 the repository, index, and working tree), commands that interrogate and
 389 compare objects, and commands that move objects and references between
 390 repositories.
 391
 392
 393 Manipulation commands
 394 ~~~~~~~~~~~~~~~~~~~~~
 395
 396 include::cmds-plumbingmanipulators.txt[]
 397
 398
 399 Interrogation commands
 400 ~~~~~~~~~~~~~~~~~~~~~~
 401
 402 include::cmds-plumbinginterrogators.txt[]
 403
 404 In general, the interrogate commands do not touch the files in
 405 the working tree.
 406
 407
 408 Synching repositories
 409 ~~~~~~~~~~~~~~~~~~~~~
 410
 411 include::cmds-synchingrepositories.txt[]
 412
 413 The following are helper commands used by the above; end users
 414 typically do not use them directly.
 415
 416 include::cmds-synchelpers.txt[]
 417
 418
 419 Internal helper commands
 420 ~~~~~~~~~~~~~~~~~~~~~~~~
 421
 422 These are internal helper commands used by other commands; end
 423 users typically do not use them directly.
 424
 425 include::cmds-purehelpers.txt[]
 426
 427
 428 Configuration Mechanism
 429 -----------------------
 430
 431 Starting from 0.99.9 (actually mid 0.99.8.GIT), `.git/config` file
 432 is used to hold per-repository configuration options.  It is a
 433 simple text file modeled after `.ini` format familiar to some
 434 people.  Here is an example:
 435
 436 ------------
 437 #
 438 # A '#' or ';' character indicates a comment.
 439 #
 440
 441 ; core variables
 442 [core]
 443         ; Don't trust file modes
 444         filemode = false
 445
 446 ; user identity
 447 [user]
 448         name = "Junio C Hamano"
 449         email = "junkio@twinsun.com"
 450
 451 ------------
 452
 453 Various commands read from the configuration file and adjust
 454 their operation accordingly.  See linkgit:git-config[1] for a
 455 list.
 456
 457
 458 Identifier Terminology
 459 ----------------------
 460 <object>::
 461         Indicates the object name for any type of object.
 462
 463 <blob>::
 464         Indicates a blob object name.
 465
 466 <tree>::
 467         Indicates a tree object name.
 468
 469 <commit>::
 470         Indicates a commit object name.
 471
 472 <tree-ish>::
 473         Indicates a tree, commit or tag object name.  A
 474         command that takes a <tree-ish> argument ultimately wants to
 475         operate on a <tree> object but automatically dereferences
 476         <commit> and <tag> objects that point at a <tree>.
 477
 478 <commit-ish>::
 479         Indicates a commit or tag object name.  A
 480         command that takes a <commit-ish> argument ultimately wants to
 481         operate on a <commit> object but automatically dereferences
 482         <tag> objects that point at a <commit>.
 483
 484 <type>::
 485         Indicates that an object type is required.
 486         Currently one of: `blob`, `tree`, `commit`, or `tag`.
 487
 488 <file>::
 489         Indicates a filename - almost always relative to the
 490         root of the tree structure `GIT_INDEX_FILE` describes.
 491
 492 Symbolic Identifiers
 493 --------------------
 494 Any git command accepting any <object> can also use the following
 495 symbolic notation:
 496
 497 HEAD::
 498         indicates the head of the current branch (i.e. the
 499         contents of `$GIT_DIR/HEAD`).
 500
 501 <tag>::
 502         a valid tag 'name'
 503         (i.e. the contents of `$GIT_DIR/refs/tags/<tag>`).
 504
 505 <head>::
 506         a valid head 'name'
 507         (i.e. the contents of `$GIT_DIR/refs/heads/<head>`).
 508
 509 For a more complete list of ways to spell object names, see
 510 "SPECIFYING REVISIONS" section in linkgit:gitrevisions[7].
 511
 512
 513 File/Directory Structure
 514 ------------------------
 515
 516 Please see the linkgit:gitrepository-layout[5] document.
 517
 518 Read linkgit:githooks[5] for more details about each hook.
 519
 520 Higher level SCMs may provide and manage additional information in the
 521 `$GIT_DIR`.
 522
 523
 524 Terminology
 525 -----------
 526 Please see linkgit:gitglossary[7].
 527
 528
 529 Environment Variables
 530 ---------------------
 531 Various git commands use the following environment variables:
 532
 533 The git Repository
 534 ~~~~~~~~~~~~~~~~~~
 535 These environment variables apply to 'all' core git commands. Nb: it
 536 is worth noting that they may be used/overridden by SCMS sitting above
 537 git so take care if using Cogito etc.
 538
 539 'GIT_INDEX_FILE'::
 540         This environment allows the specification of an alternate
 541         index file. If not specified, the default of `$GIT_DIR/index`
 542         is used.
 543
 544 'GIT_OBJECT_DIRECTORY'::
 545         If the object storage directory is specified via this
 546         environment variable then the sha1 directories are created
 547         underneath - otherwise the default `$GIT_DIR/objects`
 548         directory is used.
 549
 550 'GIT_ALTERNATE_OBJECT_DIRECTORIES'::
 551         Due to the immutable nature of git objects, old objects can be
 552         archived into shared, read-only directories. This variable
 553         specifies a ":" separated (on Windows ";" separated) list
 554         of git object directories which can be used to search for git
 555         objects. New objects will not be written to these directories.
 556
 557 'GIT_DIR'::
 558         If the 'GIT_DIR' environment variable is set then it
 559         specifies a path to use instead of the default `.git`
 560         for the base of the repository.
 561
 562 'GIT_WORK_TREE'::
 563         Set the path to the working tree.  The value will not be
 564         used in combination with repositories found automatically in
 565         a .git directory (i.e. $GIT_DIR is not set).
 566         This can also be controlled by the '--work-tree' command line
 567         option and the core.worktree configuration variable.
 568
 569 'GIT_CEILING_DIRECTORIES'::
 570         This should be a colon-separated list of absolute paths.
 571         If set, it is a list of directories that git should not chdir
 572         up into while looking for a repository directory.
 573         It will not exclude the current working directory or
 574         a GIT_DIR set on the command line or in the environment.
 575         (Useful for excluding slow-loading network directories.)
 576
 577 'GIT_DISCOVERY_ACROSS_FILESYSTEM'::
 578         When run in a directory that does not have ".git" repository
 579         directory, git tries to find such a directory in the parent
 580         directories to find the top of the working tree, but by default it
 581         does not cross filesystem boundaries.  This environment variable
 582         can be set to true to tell git not to stop at filesystem
 583         boundaries.  Like 'GIT_CEILING_DIRECTORIES', this will not affect
 584         an explicit repository directory set via 'GIT_DIR' or on the
 585         command line.
 586
 587 git Commits
 588 ~~~~~~~~~~~
 589 'GIT_AUTHOR_NAME'::
 590 'GIT_AUTHOR_EMAIL'::
 591 'GIT_AUTHOR_DATE'::
 592 'GIT_COMMITTER_NAME'::
 593 'GIT_COMMITTER_EMAIL'::
 594 'GIT_COMMITTER_DATE'::
 595 'EMAIL'::
 596         see linkgit:git-commit-tree[1]
 597
 598 git Diffs
 599 ~~~~~~~~~
 600 'GIT_DIFF_OPTS'::
 601         Only valid setting is "--unified=??" or "-u??" to set the
 602         number of context lines shown when a unified diff is created.
 603         This takes precedence over any "-U" or "--unified" option
 604         value passed on the git diff command line.
 605
 606 'GIT_EXTERNAL_DIFF'::
 607         When the environment variable 'GIT_EXTERNAL_DIFF' is set, the
 608         program named by it is called, instead of the diff invocation
 609         described above.  For a path that is added, removed, or modified,
 610         'GIT_EXTERNAL_DIFF' is called with 7 parameters:
 611
 612         path old-file old-hex old-mode new-file new-hex new-mode
 613 +
 614 where:
 615
 616         <old|new>-file:: are files GIT_EXTERNAL_DIFF can use to read the
 617                          contents of <old|new>,
 618         <old|new>-hex:: are the 40-hexdigit SHA1 hashes,
 619         <old|new>-mode:: are the octal representation of the file modes.
 620
 621 +
 622 The file parameters can point at the user's working file
 623 (e.g. `new-file` in "git-diff-files"), `/dev/null` (e.g. `old-file`
 624 when a new file is added), or a temporary file (e.g. `old-file` in the
 625 index).  'GIT_EXTERNAL_DIFF' should not worry about unlinking the
 626 temporary file --- it is removed when 'GIT_EXTERNAL_DIFF' exits.
 627 +
 628 For a path that is unmerged, 'GIT_EXTERNAL_DIFF' is called with 1
 629 parameter, <path>.
 630
 631 other
 632 ~~~~~
 633 'GIT_MERGE_VERBOSITY'::
 634         A number controlling the amount of output shown by
 635         the recursive merge strategy.  Overrides merge.verbosity.
 636         See linkgit:git-merge[1]
 637
 638 'GIT_PAGER'::
 639         This environment variable overrides `$PAGER`. If it is set
 640         to an empty string or to the value "cat", git will not launch
 641         a pager.  See also the `core.pager` option in
 642         linkgit:git-config[1].
 643
 644 'GIT_SSH'::
 645         If this environment variable is set then 'git fetch'
 646         and 'git push' will use this command instead
 647         of 'ssh' when they need to connect to a remote system.
 648         The '$GIT_SSH' command will be given exactly two arguments:
 649         the 'username@host' (or just 'host') from the URL and the
 650         shell command to execute on that remote system.
 651 +
 652 To pass options to the program that you want to list in GIT_SSH
 653 you will need to wrap the program and options into a shell script,
 654 then set GIT_SSH to refer to the shell script.
 655 +
 656 Usually it is easier to configure any desired options through your
 657 personal `.ssh/config` file.  Please consult your ssh documentation
 658 for further details.
 659
 660 'GIT_ASKPASS'::
 661         If this environment variable is set, then git commands which need to
 662         acquire passwords or passphrases (e.g. for HTTP or IMAP authentication)
 663         will call this program with a suitable prompt as command line argument
 664         and read the password from its STDOUT. See also the 'core.askpass'
 665         option in linkgit:git-config[1].
 666
 667 'GIT_FLUSH'::
 668         If this environment variable is set to "1", then commands such
 669         as 'git blame' (in incremental mode), 'git rev-list', 'git log',
 670         and 'git whatchanged' will force a flush of the output stream
 671         after each commit-oriented record have been flushed.   If this
 672         variable is set to "0", the output of these commands will be done
 673         using completely buffered I/O.   If this environment variable is
 674         not set, git will choose buffered or record-oriented flushing
 675         based on whether stdout appears to be redirected to a file or not.
 676
 677 'GIT_TRACE'::
 678         If this variable is set to "1", "2" or "true" (comparison
 679         is case insensitive), git will print `trace:` messages on
 680         stderr telling about alias expansion, built-in command
 681         execution and external command execution.
 682         If this variable is set to an integer value greater than 1
 683         and lower than 10 (strictly) then git will interpret this
 684         value as an open file descriptor and will try to write the
 685         trace messages into this file descriptor.
 686         Alternatively, if this variable is set to an absolute path
 687         (starting with a '/' character), git will interpret this
 688         as a file path and will try to write the trace messages
 689         into it.
 690
 691 Discussion[[Discussion]]
 692 ------------------------
 693
 694 More detail on the following is available from the
 695 link:user-manual.html#git-concepts[git concepts chapter of the
 696 user-manual] and linkgit:gitcore-tutorial[7].
 697
 698 A git project normally consists of a working directory with a ".git"
 699 subdirectory at the top level.  The .git directory contains, among other
 700 things, a compressed object database representing the complete history
 701 of the project, an "index" file which links that history to the current
 702 contents of the working tree, and named pointers into that history such
 703 as tags and branch heads.
 704
 705 The object database contains objects of three main types: blobs, which
 706 hold file data; trees, which point to blobs and other trees to build up
 707 directory hierarchies; and commits, which each reference a single tree
 708 and some number of parent commits.
 709
 710 The commit, equivalent to what other systems call a "changeset" or
 711 "version", represents a step in the project's history, and each parent
 712 represents an immediately preceding step.  Commits with more than one
 713 parent represent merges of independent lines of development.
 714
 715 All objects are named by the SHA1 hash of their contents, normally
 716 written as a string of 40 hex digits.  Such names are globally unique.
 717 The entire history leading up to a commit can be vouched for by signing
 718 just that commit.  A fourth object type, the tag, is provided for this
 719 purpose.
 720
 721 When first created, objects are stored in individual files, but for
 722 efficiency may later be compressed together into "pack files".
 723
 724 Named pointers called refs mark interesting points in history.  A ref
 725 may contain the SHA1 name of an object or the name of another ref.  Refs
 726 with names beginning `ref/head/` contain the SHA1 name of the most
 727 recent commit (or "head") of a branch under development.  SHA1 names of
 728 tags of interest are stored under `ref/tags/`.  A special ref named
 729 `HEAD` contains the name of the currently checked-out branch.
 730
 731 The index file is initialized with a list of all paths and, for each
 732 path, a blob object and a set of attributes.  The blob object represents
 733 the contents of the file as of the head of the current branch.  The
 734 attributes (last modified time, size, etc.) are taken from the
 735 corresponding file in the working tree.  Subsequent changes to the
 736 working tree can be found by comparing these attributes.  The index may
 737 be updated with new content, and new commits may be created from the
 738 content stored in the index.
 739
 740 The index is also capable of storing multiple entries (called "stages")
 741 for a given pathname.  These stages are used to hold the various
 742 unmerged version of a file when a merge is in progress.
 743
 744 Authors
 745 -------
 746 * git's founding father is Linus Torvalds <torvalds@osdl.org>.
 747 * The current git nurse is Junio C Hamano <gitster@pobox.com>.
 748 * The git potty was written by Andreas Ericsson <ae@op5.se>.
 749 * General upbringing is handled by the git-list <git@vger.kernel.org>.
 750
 751 Documentation
 752 --------------
 753 The documentation for git suite was started by David Greaves
 754 <david@dgreaves.com>, and later enhanced greatly by the
 755 contributors on the git-list <git@vger.kernel.org>.
 756
 757 Reporting Bugs
 758 --------------
 759
 760 Report bugs to the Git mailing list <git@vger.kernel.org> where the
 761 development and maintenance is primarily done.  You do not have to be
 762 subscribed to the list to send a message there.
 763
 764 SEE ALSO
 765 --------
 766 linkgit:gittutorial[7], linkgit:gittutorial-2[7],
 767 link:everyday.html[Everyday Git], linkgit:gitcvs-migration[7],
 768 linkgit:gitglossary[7], linkgit:gitcore-tutorial[7],
 769 linkgit:gitcli[7], link:user-manual.html[The Git User's Manual],
 770 linkgit:gitworkflows[7]
 771
 772 GIT
 773 ---
 774 Part of the linkgit:git[1] suite