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:v1.7.4/git.html[documentation for release 1.7.4]
  48
  49 * release notes for
  50   link:RelNotes/1.7.4.txt[1.7.4].
  51
  52 * link:v1.7.3.5/git.html[documentation for release 1.7.3.5]
  53
  54 * release notes for
  55   link:RelNotes/1.7.3.5.txt[1.7.3.5],
  56   link:RelNotes/1.7.3.4.txt[1.7.3.4],
  57   link:RelNotes/1.7.3.3.txt[1.7.3.3],
  58   link:RelNotes/1.7.3.2.txt[1.7.3.2],
  59   link:RelNotes/1.7.3.1.txt[1.7.3.1],
  60   link:RelNotes/1.7.3.txt[1.7.3].
  61
  62 * link:v1.7.2.5/git.html[documentation for release 1.7.2.5]
  63
  64 * release notes for
  65   link:RelNotes/1.7.2.5.txt[1.7.2.5],
  66   link:RelNotes/1.7.2.4.txt[1.7.2.4],
  67   link:RelNotes/1.7.2.3.txt[1.7.2.3],
  68   link:RelNotes/1.7.2.2.txt[1.7.2.2],
  69   link:RelNotes/1.7.2.1.txt[1.7.2.1],
  70   link:RelNotes/1.7.2.txt[1.7.2].
  71
  72 * link:v1.7.1.4/git.html[documentation for release 1.7.1.4]
  73
  74 * release notes for
  75   link:RelNotes/1.7.1.4.txt[1.7.1.4],
  76   link:RelNotes/1.7.1.3.txt[1.7.1.3],
  77   link:RelNotes/1.7.1.2.txt[1.7.1.2],
  78   link:RelNotes/1.7.1.1.txt[1.7.1.1],
  79   link:RelNotes/1.7.1.txt[1.7.1].
  80
  81 * link:v1.7.0.9/git.html[documentation for release 1.7.0.9]
  82
  83 * release notes for
  84   link:RelNotes/1.7.0.9.txt[1.7.0.9],
  85   link:RelNotes/1.7.0.8.txt[1.7.0.8],
  86   link:RelNotes/1.7.0.7.txt[1.7.0.7],
  87   link:RelNotes/1.7.0.6.txt[1.7.0.6],
  88   link:RelNotes/1.7.0.5.txt[1.7.0.5],
  89   link:RelNotes/1.7.0.4.txt[1.7.0.4],
  90   link:RelNotes/1.7.0.3.txt[1.7.0.3],
  91   link:RelNotes/1.7.0.2.txt[1.7.0.2],
  92   link:RelNotes/1.7.0.1.txt[1.7.0.1],
  93   link:RelNotes/1.7.0.txt[1.7.0].
  94
  95 * link:v1.6.6.3/git.html[documentation for release 1.6.6.3]
  96
  97 * release notes for
  98   link:RelNotes/1.6.6.3.txt[1.6.6.3],
  99   link:RelNotes/1.6.6.2.txt[1.6.6.2],
 100   link:RelNotes/1.6.6.1.txt[1.6.6.1],
 101   link:RelNotes/1.6.6.txt[1.6.6].
 102
 103 * link:v1.6.5.9/git.html[documentation for release 1.6.5.9]
 104
 105 * release notes for
 106   link:RelNotes/1.6.5.9.txt[1.6.5.9],
 107   link:RelNotes/1.6.5.8.txt[1.6.5.8],
 108   link:RelNotes/1.6.5.7.txt[1.6.5.7],
 109   link:RelNotes/1.6.5.6.txt[1.6.5.6],
 110   link:RelNotes/1.6.5.5.txt[1.6.5.5],
 111   link:RelNotes/1.6.5.4.txt[1.6.5.4],
 112   link:RelNotes/1.6.5.3.txt[1.6.5.3],
 113   link:RelNotes/1.6.5.2.txt[1.6.5.2],
 114   link:RelNotes/1.6.5.1.txt[1.6.5.1],
 115   link:RelNotes/1.6.5.txt[1.6.5].
 116
 117 * link:v1.6.4.5/git.html[documentation for release 1.6.4.5]
 118
 119 * release notes for
 120   link:RelNotes/1.6.4.5.txt[1.6.4.5],
 121   link:RelNotes/1.6.4.4.txt[1.6.4.4],
 122   link:RelNotes/1.6.4.3.txt[1.6.4.3],
 123   link:RelNotes/1.6.4.2.txt[1.6.4.2],
 124   link:RelNotes/1.6.4.1.txt[1.6.4.1],
 125   link:RelNotes/1.6.4.txt[1.6.4].
 126
 127 * link:v1.6.3.4/git.html[documentation for release 1.6.3.4]
 128
 129 * release notes for
 130   link:RelNotes/1.6.3.4.txt[1.6.3.4],
 131   link:RelNotes/1.6.3.3.txt[1.6.3.3],
 132   link:RelNotes/1.6.3.2.txt[1.6.3.2],
 133   link:RelNotes/1.6.3.1.txt[1.6.3.1],
 134   link:RelNotes/1.6.3.txt[1.6.3].
 135
 136 * release notes for
 137   link:RelNotes/1.6.2.5.txt[1.6.2.5],
 138   link:RelNotes/1.6.2.4.txt[1.6.2.4],
 139   link:RelNotes/1.6.2.3.txt[1.6.2.3],
 140   link:RelNotes/1.6.2.2.txt[1.6.2.2],
 141   link:RelNotes/1.6.2.1.txt[1.6.2.1],
 142   link:RelNotes/1.6.2.txt[1.6.2].
 143
 144 * link:v1.6.1.3/git.html[documentation for release 1.6.1.3]
 145
 146 * release notes for
 147   link:RelNotes/1.6.1.3.txt[1.6.1.3],
 148   link:RelNotes/1.6.1.2.txt[1.6.1.2],
 149   link:RelNotes/1.6.1.1.txt[1.6.1.1],
 150   link:RelNotes/1.6.1.txt[1.6.1].
 151
 152 * link:v1.6.0.6/git.html[documentation for release 1.6.0.6]
 153
 154 * release notes for
 155   link:RelNotes/1.6.0.6.txt[1.6.0.6],
 156   link:RelNotes/1.6.0.5.txt[1.6.0.5],
 157   link:RelNotes/1.6.0.4.txt[1.6.0.4],
 158   link:RelNotes/1.6.0.3.txt[1.6.0.3],
 159   link:RelNotes/1.6.0.2.txt[1.6.0.2],
 160   link:RelNotes/1.6.0.1.txt[1.6.0.1],
 161   link:RelNotes/1.6.0.txt[1.6.0].
 162
 163 * link:v1.5.6.6/git.html[documentation for release 1.5.6.6]
 164
 165 * release notes for
 166   link:RelNotes/1.5.6.6.txt[1.5.6.6],
 167   link:RelNotes/1.5.6.5.txt[1.5.6.5],
 168   link:RelNotes/1.5.6.4.txt[1.5.6.4],
 169   link:RelNotes/1.5.6.3.txt[1.5.6.3],
 170   link:RelNotes/1.5.6.2.txt[1.5.6.2],
 171   link:RelNotes/1.5.6.1.txt[1.5.6.1],
 172   link:RelNotes/1.5.6.txt[1.5.6].
 173
 174 * link:v1.5.5.6/git.html[documentation for release 1.5.5.6]
 175
 176 * release notes for
 177   link:RelNotes/1.5.5.6.txt[1.5.5.6],
 178   link:RelNotes/1.5.5.5.txt[1.5.5.5],
 179   link:RelNotes/1.5.5.4.txt[1.5.5.4],
 180   link:RelNotes/1.5.5.3.txt[1.5.5.3],
 181   link:RelNotes/1.5.5.2.txt[1.5.5.2],
 182   link:RelNotes/1.5.5.1.txt[1.5.5.1],
 183   link:RelNotes/1.5.5.txt[1.5.5].
 184
 185 * link:v1.5.4.7/git.html[documentation for release 1.5.4.7]
 186
 187 * release notes for
 188   link:RelNotes/1.5.4.7.txt[1.5.4.7],
 189   link:RelNotes/1.5.4.6.txt[1.5.4.6],
 190   link:RelNotes/1.5.4.5.txt[1.5.4.5],
 191   link:RelNotes/1.5.4.4.txt[1.5.4.4],
 192   link:RelNotes/1.5.4.3.txt[1.5.4.3],
 193   link:RelNotes/1.5.4.2.txt[1.5.4.2],
 194   link:RelNotes/1.5.4.1.txt[1.5.4.1],
 195   link:RelNotes/1.5.4.txt[1.5.4].
 196
 197 * link:v1.5.3.8/git.html[documentation for release 1.5.3.8]
 198
 199 * release notes for
 200   link:RelNotes/1.5.3.8.txt[1.5.3.8],
 201   link:RelNotes/1.5.3.7.txt[1.5.3.7],
 202   link:RelNotes/1.5.3.6.txt[1.5.3.6],
 203   link:RelNotes/1.5.3.5.txt[1.5.3.5],
 204   link:RelNotes/1.5.3.4.txt[1.5.3.4],
 205   link:RelNotes/1.5.3.3.txt[1.5.3.3],
 206   link:RelNotes/1.5.3.2.txt[1.5.3.2],
 207   link:RelNotes/1.5.3.1.txt[1.5.3.1],
 208   link:RelNotes/1.5.3.txt[1.5.3].
 209
 210 * link:v1.5.2.5/git.html[documentation for release 1.5.2.5]
 211
 212 * release notes for
 213   link:RelNotes/1.5.2.5.txt[1.5.2.5],
 214   link:RelNotes/1.5.2.4.txt[1.5.2.4],
 215   link:RelNotes/1.5.2.3.txt[1.5.2.3],
 216   link:RelNotes/1.5.2.2.txt[1.5.2.2],
 217   link:RelNotes/1.5.2.1.txt[1.5.2.1],
 218   link:RelNotes/1.5.2.txt[1.5.2].
 219
 220 * link:v1.5.1.6/git.html[documentation for release 1.5.1.6]
 221
 222 * release notes for
 223   link:RelNotes/1.5.1.6.txt[1.5.1.6],
 224   link:RelNotes/1.5.1.5.txt[1.5.1.5],
 225   link:RelNotes/1.5.1.4.txt[1.5.1.4],
 226   link:RelNotes/1.5.1.3.txt[1.5.1.3],
 227   link:RelNotes/1.5.1.2.txt[1.5.1.2],
 228   link:RelNotes/1.5.1.1.txt[1.5.1.1],
 229   link:RelNotes/1.5.1.txt[1.5.1].
 230
 231 * link:v1.5.0.7/git.html[documentation for release 1.5.0.7]
 232
 233 * release notes for
 234   link:RelNotes/1.5.0.7.txt[1.5.0.7],
 235   link:RelNotes/1.5.0.6.txt[1.5.0.6],
 236   link:RelNotes/1.5.0.5.txt[1.5.0.5],
 237   link:RelNotes/1.5.0.3.txt[1.5.0.3],
 238   link:RelNotes/1.5.0.2.txt[1.5.0.2],
 239   link:RelNotes/1.5.0.1.txt[1.5.0.1],
 240   link:RelNotes/1.5.0.txt[1.5.0].
 241
 242 * documentation for release link:v1.4.4.4/git.html[1.4.4.4],
 243   link:v1.3.3/git.html[1.3.3],
 244   link:v1.2.6/git.html[1.2.6],
 245   link:v1.0.13/git.html[1.0.13].
 246
 247 ============
 248
 249 endif::stalenotes[]
 250
 251 OPTIONS
 252 -------
 253 --version::
 254         Prints the git suite version that the 'git' program came from.
 255
 256 --help::
 257         Prints the synopsis and a list of the most commonly used
 258         commands. If the option '--all' or '-a' is given then all
 259         available commands are printed. If a git command is named this
 260         option will bring up the manual page for that command.
 261 +
 262 Other options are available to control how the manual page is
 263 displayed. See linkgit:git-help[1] for more information,
 264 because `git --help ...` is converted internally into `git
 265 help ...`.
 266
 267 -c <name>=<value>::
 268         Pass a configuration parameter to the command. The value
 269         given will override values from configuration files.
 270         The <name> is expected in the same format as listed by
 271         'git config' (subkeys separated by dots).
 272
 273 --exec-path[=<path>]::
 274         Path to wherever your core git programs are installed.
 275         This can also be controlled by setting the GIT_EXEC_PATH
 276         environment variable. If no path is given, 'git' will print
 277         the current setting and then exit.
 278
 279 --html-path::
 280         Print the path to wherever your git HTML documentation is installed
 281         and exit.
 282
 283 -p::
 284 --paginate::
 285         Pipe all output into 'less' (or if set, $PAGER) if standard
 286         output is a terminal.  This overrides the `pager.<cmd>`
 287         configuration options (see the "Configuration Mechanism" section
 288         below).
 289
 290 --no-pager::
 291         Do not pipe git output into a pager.
 292
 293 --git-dir=<path>::
 294         Set the path to the repository. This can also be controlled by
 295         setting the GIT_DIR environment variable. It can be an absolute
 296         path or relative path to current working directory.
 297
 298 --work-tree=<path>::
 299         Set the path to the working tree. It can be an absolute path
 300         or a path relative to the current working directory.
 301         This can also be controlled by setting the GIT_WORK_TREE
 302         environment variable and the core.worktree configuration
 303         variable (see core.worktree in linkgit:git-config[1] for a
 304         more detailed discussion).
 305
 306 --bare::
 307         Treat the repository as a bare repository.  If GIT_DIR
 308         environment is not set, it is set to the current working
 309         directory.
 310
 311 --no-replace-objects::
 312         Do not use replacement refs to replace git objects. See
 313         linkgit:git-replace[1] for more information.
 314
 315
 316 FURTHER DOCUMENTATION
 317 ---------------------
 318
 319 See the references above to get started using git.  The following is
 320 probably more detail than necessary for a first-time user.
 321
 322 The link:user-manual.html#git-concepts[git concepts chapter of the
 323 user-manual] and linkgit:gitcore-tutorial[7] both provide
 324 introductions to the underlying git architecture.
 325
 326 See linkgit:gitworkflows[7] for an overview of recommended workflows.
 327
 328 See also the link:howto-index.html[howto] documents for some useful
 329 examples.
 330
 331 The internals are documented in the
 332 link:technical/api-index.html[GIT API documentation].
 333
 334 GIT COMMANDS
 335 ------------
 336
 337 We divide git into high level ("porcelain") commands and low level
 338 ("plumbing") commands.
 339
 340 High-level commands (porcelain)
 341 -------------------------------
 342
 343 We separate the porcelain commands into the main commands and some
 344 ancillary user utilities.
 345
 346 Main porcelain commands
 347 ~~~~~~~~~~~~~~~~~~~~~~~
 348
 349 include::cmds-mainporcelain.txt[]
 350
 351 Ancillary Commands
 352 ~~~~~~~~~~~~~~~~~~
 353 Manipulators:
 354
 355 include::cmds-ancillarymanipulators.txt[]
 356
 357 Interrogators:
 358
 359 include::cmds-ancillaryinterrogators.txt[]
 360
 361
 362 Interacting with Others
 363 ~~~~~~~~~~~~~~~~~~~~~~~
 364
 365 These commands are to interact with foreign SCM and with other
 366 people via patch over e-mail.
 367
 368 include::cmds-foreignscminterface.txt[]
 369
 370
 371 Low-level commands (plumbing)
 372 -----------------------------
 373
 374 Although git includes its
 375 own porcelain layer, its low-level commands are sufficient to support
 376 development of alternative porcelains.  Developers of such porcelains
 377 might start by reading about linkgit:git-update-index[1] and
 378 linkgit:git-read-tree[1].
 379
 380 The interface (input, output, set of options and the semantics)
 381 to these low-level commands are meant to be a lot more stable
 382 than Porcelain level commands, because these commands are
 383 primarily for scripted use.  The interface to Porcelain commands
 384 on the other hand are subject to change in order to improve the
 385 end user experience.
 386
 387 The following description divides
 388 the low-level commands into commands that manipulate objects (in
 389 the repository, index, and working tree), commands that interrogate and
 390 compare objects, and commands that move objects and references between
 391 repositories.
 392
 393
 394 Manipulation commands
 395 ~~~~~~~~~~~~~~~~~~~~~
 396
 397 include::cmds-plumbingmanipulators.txt[]
 398
 399
 400 Interrogation commands
 401 ~~~~~~~~~~~~~~~~~~~~~~
 402
 403 include::cmds-plumbinginterrogators.txt[]
 404
 405 In general, the interrogate commands do not touch the files in
 406 the working tree.
 407
 408
 409 Synching repositories
 410 ~~~~~~~~~~~~~~~~~~~~~
 411
 412 include::cmds-synchingrepositories.txt[]
 413
 414 The following are helper commands used by the above; end users
 415 typically do not use them directly.
 416
 417 include::cmds-synchelpers.txt[]
 418
 419
 420 Internal helper commands
 421 ~~~~~~~~~~~~~~~~~~~~~~~~
 422
 423 These are internal helper commands used by other commands; end
 424 users typically do not use them directly.
 425
 426 include::cmds-purehelpers.txt[]
 427
 428
 429 Configuration Mechanism
 430 -----------------------
 431
 432 Starting from 0.99.9 (actually mid 0.99.8.GIT), `.git/config` file
 433 is used to hold per-repository configuration options.  It is a
 434 simple text file modeled after `.ini` format familiar to some
 435 people.  Here is an example:
 436
 437 ------------
 438 #
 439 # A '#' or ';' character indicates a comment.
 440 #
 441
 442 ; core variables
 443 [core]
 444         ; Don't trust file modes
 445         filemode = false
 446
 447 ; user identity
 448 [user]
 449         name = "Junio C Hamano"
 450         email = "junkio@twinsun.com"
 451
 452 ------------
 453
 454 Various commands read from the configuration file and adjust
 455 their operation accordingly.  See linkgit:git-config[1] for a
 456 list.
 457
 458
 459 Identifier Terminology
 460 ----------------------
 461 <object>::
 462         Indicates the object name for any type of object.
 463
 464 <blob>::
 465         Indicates a blob object name.
 466
 467 <tree>::
 468         Indicates a tree object name.
 469
 470 <commit>::
 471         Indicates a commit object name.
 472
 473 <tree-ish>::
 474         Indicates a tree, commit or tag object name.  A
 475         command that takes a <tree-ish> argument ultimately wants to
 476         operate on a <tree> object but automatically dereferences
 477         <commit> and <tag> objects that point at a <tree>.
 478
 479 <commit-ish>::
 480         Indicates a commit or tag object name.  A
 481         command that takes a <commit-ish> argument ultimately wants to
 482         operate on a <commit> object but automatically dereferences
 483         <tag> objects that point at a <commit>.
 484
 485 <type>::
 486         Indicates that an object type is required.
 487         Currently one of: `blob`, `tree`, `commit`, or `tag`.
 488
 489 <file>::
 490         Indicates a filename - almost always relative to the
 491         root of the tree structure `GIT_INDEX_FILE` describes.
 492
 493 Symbolic Identifiers
 494 --------------------
 495 Any git command accepting any <object> can also use the following
 496 symbolic notation:
 497
 498 HEAD::
 499         indicates the head of the current branch (i.e. the
 500         contents of `$GIT_DIR/HEAD`).
 501
 502 <tag>::
 503         a valid tag 'name'
 504         (i.e. the contents of `$GIT_DIR/refs/tags/<tag>`).
 505
 506 <head>::
 507         a valid head 'name'
 508         (i.e. the contents of `$GIT_DIR/refs/heads/<head>`).
 509
 510 For a more complete list of ways to spell object names, see
 511 "SPECIFYING REVISIONS" section in linkgit:gitrevisions[7].
 512
 513
 514 File/Directory Structure
 515 ------------------------
 516
 517 Please see the linkgit:gitrepository-layout[5] document.
 518
 519 Read linkgit:githooks[5] for more details about each hook.
 520
 521 Higher level SCMs may provide and manage additional information in the
 522 `$GIT_DIR`.
 523
 524
 525 Terminology
 526 -----------
 527 Please see linkgit:gitglossary[7].
 528
 529
 530 Environment Variables
 531 ---------------------
 532 Various git commands use the following environment variables:
 533
 534 The git Repository
 535 ~~~~~~~~~~~~~~~~~~
 536 These environment variables apply to 'all' core git commands. Nb: it
 537 is worth noting that they may be used/overridden by SCMS sitting above
 538 git so take care if using Cogito etc.
 539
 540 'GIT_INDEX_FILE'::
 541         This environment allows the specification of an alternate
 542         index file. If not specified, the default of `$GIT_DIR/index`
 543         is used.
 544
 545 'GIT_OBJECT_DIRECTORY'::
 546         If the object storage directory is specified via this
 547         environment variable then the sha1 directories are created
 548         underneath - otherwise the default `$GIT_DIR/objects`
 549         directory is used.
 550
 551 'GIT_ALTERNATE_OBJECT_DIRECTORIES'::
 552         Due to the immutable nature of git objects, old objects can be
 553         archived into shared, read-only directories. This variable
 554         specifies a ":" separated (on Windows ";" separated) list
 555         of git object directories which can be used to search for git
 556         objects. New objects will not be written to these directories.
 557
 558 'GIT_DIR'::
 559         If the 'GIT_DIR' environment variable is set then it
 560         specifies a path to use instead of the default `.git`
 561         for the base of the repository.
 562
 563 'GIT_WORK_TREE'::
 564         Set the path to the working tree.  The value will not be
 565         used in combination with repositories found automatically in
 566         a .git directory (i.e. $GIT_DIR is not set).
 567         This can also be controlled by the '--work-tree' command line
 568         option and the core.worktree configuration variable.
 569
 570 'GIT_CEILING_DIRECTORIES'::
 571         This should be a colon-separated list of absolute paths.
 572         If set, it is a list of directories that git should not chdir
 573         up into while looking for a repository directory.
 574         It will not exclude the current working directory or
 575         a GIT_DIR set on the command line or in the environment.
 576         (Useful for excluding slow-loading network directories.)
 577
 578 'GIT_DISCOVERY_ACROSS_FILESYSTEM'::
 579         When run in a directory that does not have ".git" repository
 580         directory, git tries to find such a directory in the parent
 581         directories to find the top of the working tree, but by default it
 582         does not cross filesystem boundaries.  This environment variable
 583         can be set to true to tell git not to stop at filesystem
 584         boundaries.  Like 'GIT_CEILING_DIRECTORIES', this will not affect
 585         an explicit repository directory set via 'GIT_DIR' or on the
 586         command line.
 587
 588 git Commits
 589 ~~~~~~~~~~~
 590 'GIT_AUTHOR_NAME'::
 591 'GIT_AUTHOR_EMAIL'::
 592 'GIT_AUTHOR_DATE'::
 593 'GIT_COMMITTER_NAME'::
 594 'GIT_COMMITTER_EMAIL'::
 595 'GIT_COMMITTER_DATE'::
 596 'EMAIL'::
 597         see linkgit:git-commit-tree[1]
 598
 599 git Diffs
 600 ~~~~~~~~~
 601 'GIT_DIFF_OPTS'::
 602         Only valid setting is "--unified=??" or "-u??" to set the
 603         number of context lines shown when a unified diff is created.
 604         This takes precedence over any "-U" or "--unified" option
 605         value passed on the git diff command line.
 606
 607 'GIT_EXTERNAL_DIFF'::
 608         When the environment variable 'GIT_EXTERNAL_DIFF' is set, the
 609         program named by it is called, instead of the diff invocation
 610         described above.  For a path that is added, removed, or modified,
 611         'GIT_EXTERNAL_DIFF' is called with 7 parameters:
 612
 613         path old-file old-hex old-mode new-file new-hex new-mode
 614 +
 615 where:
 616
 617         <old|new>-file:: are files GIT_EXTERNAL_DIFF can use to read the
 618                          contents of <old|new>,
 619         <old|new>-hex:: are the 40-hexdigit SHA1 hashes,
 620         <old|new>-mode:: are the octal representation of the file modes.
 621
 622 +
 623 The file parameters can point at the user's working file
 624 (e.g. `new-file` in "git-diff-files"), `/dev/null` (e.g. `old-file`
 625 when a new file is added), or a temporary file (e.g. `old-file` in the
 626 index).  'GIT_EXTERNAL_DIFF' should not worry about unlinking the
 627 temporary file --- it is removed when 'GIT_EXTERNAL_DIFF' exits.
 628 +
 629 For a path that is unmerged, 'GIT_EXTERNAL_DIFF' is called with 1
 630 parameter, <path>.
 631
 632 other
 633 ~~~~~
 634 'GIT_MERGE_VERBOSITY'::
 635         A number controlling the amount of output shown by
 636         the recursive merge strategy.  Overrides merge.verbosity.
 637         See linkgit:git-merge[1]
 638
 639 'GIT_PAGER'::
 640         This environment variable overrides `$PAGER`. If it is set
 641         to an empty string or to the value "cat", git will not launch
 642         a pager.  See also the `core.pager` option in
 643         linkgit:git-config[1].
 644
 645 'GIT_SSH'::
 646         If this environment variable is set then 'git fetch'
 647         and 'git push' will use this command instead
 648         of 'ssh' when they need to connect to a remote system.
 649         The '$GIT_SSH' command will be given exactly two arguments:
 650         the 'username@host' (or just 'host') from the URL and the
 651         shell command to execute on that remote system.
 652 +
 653 To pass options to the program that you want to list in GIT_SSH
 654 you will need to wrap the program and options into a shell script,
 655 then set GIT_SSH to refer to the shell script.
 656 +
 657 Usually it is easier to configure any desired options through your
 658 personal `.ssh/config` file.  Please consult your ssh documentation
 659 for further details.
 660
 661 'GIT_ASKPASS'::
 662         If this environment variable is set, then git commands which need to
 663         acquire passwords or passphrases (e.g. for HTTP or IMAP authentication)
 664         will call this program with a suitable prompt as command line argument
 665         and read the password from its STDOUT. See also the 'core.askpass'
 666         option in linkgit:git-config[1].
 667
 668 'GIT_FLUSH'::
 669         If this environment variable is set to "1", then commands such
 670         as 'git blame' (in incremental mode), 'git rev-list', 'git log',
 671         and 'git whatchanged' will force a flush of the output stream
 672         after each commit-oriented record have been flushed.   If this
 673         variable is set to "0", the output of these commands will be done
 674         using completely buffered I/O.   If this environment variable is
 675         not set, git will choose buffered or record-oriented flushing
 676         based on whether stdout appears to be redirected to a file or not.
 677
 678 'GIT_TRACE'::
 679         If this variable is set to "1", "2" or "true" (comparison
 680         is case insensitive), git will print `trace:` messages on
 681         stderr telling about alias expansion, built-in command
 682         execution and external command execution.
 683         If this variable is set to an integer value greater than 1
 684         and lower than 10 (strictly) then git will interpret this
 685         value as an open file descriptor and will try to write the
 686         trace messages into this file descriptor.
 687         Alternatively, if this variable is set to an absolute path
 688         (starting with a '/' character), git will interpret this
 689         as a file path and will try to write the trace messages
 690         into it.
 691
 692 Discussion[[Discussion]]
 693 ------------------------
 694
 695 More detail on the following is available from the
 696 link:user-manual.html#git-concepts[git concepts chapter of the
 697 user-manual] and linkgit:gitcore-tutorial[7].
 698
 699 A git project normally consists of a working directory with a ".git"
 700 subdirectory at the top level.  The .git directory contains, among other
 701 things, a compressed object database representing the complete history
 702 of the project, an "index" file which links that history to the current
 703 contents of the working tree, and named pointers into that history such
 704 as tags and branch heads.
 705
 706 The object database contains objects of three main types: blobs, which
 707 hold file data; trees, which point to blobs and other trees to build up
 708 directory hierarchies; and commits, which each reference a single tree
 709 and some number of parent commits.
 710
 711 The commit, equivalent to what other systems call a "changeset" or
 712 "version", represents a step in the project's history, and each parent
 713 represents an immediately preceding step.  Commits with more than one
 714 parent represent merges of independent lines of development.
 715
 716 All objects are named by the SHA1 hash of their contents, normally
 717 written as a string of 40 hex digits.  Such names are globally unique.
 718 The entire history leading up to a commit can be vouched for by signing
 719 just that commit.  A fourth object type, the tag, is provided for this
 720 purpose.
 721
 722 When first created, objects are stored in individual files, but for
 723 efficiency may later be compressed together into "pack files".
 724
 725 Named pointers called refs mark interesting points in history.  A ref
 726 may contain the SHA1 name of an object or the name of another ref.  Refs
 727 with names beginning `ref/head/` contain the SHA1 name of the most
 728 recent commit (or "head") of a branch under development.  SHA1 names of
 729 tags of interest are stored under `ref/tags/`.  A special ref named
 730 `HEAD` contains the name of the currently checked-out branch.
 731
 732 The index file is initialized with a list of all paths and, for each
 733 path, a blob object and a set of attributes.  The blob object represents
 734 the contents of the file as of the head of the current branch.  The
 735 attributes (last modified time, size, etc.) are taken from the
 736 corresponding file in the working tree.  Subsequent changes to the
 737 working tree can be found by comparing these attributes.  The index may
 738 be updated with new content, and new commits may be created from the
 739 content stored in the index.
 740
 741 The index is also capable of storing multiple entries (called "stages")
 742 for a given pathname.  These stages are used to hold the various
 743 unmerged version of a file when a merge is in progress.
 744
 745 Authors
 746 -------
 747 * git's founding father is Linus Torvalds <torvalds@osdl.org>.
 748 * The current git nurse is Junio C Hamano <gitster@pobox.com>.
 749 * The git potty was written by Andreas Ericsson <ae@op5.se>.
 750 * General upbringing is handled by the git-list <git@vger.kernel.org>.
 751
 752 Documentation
 753 --------------
 754 The documentation for git suite was started by David Greaves
 755 <david@dgreaves.com>, and later enhanced greatly by the
 756 contributors on the git-list <git@vger.kernel.org>.
 757
 758 Reporting Bugs
 759 --------------
 760
 761 Report bugs to the Git mailing list <git@vger.kernel.org> where the
 762 development and maintenance is primarily done.  You do not have to be
 763 subscribed to the list to send a message there.
 764
 765 SEE ALSO
 766 --------
 767 linkgit:gittutorial[7], linkgit:gittutorial-2[7],
 768 link:everyday.html[Everyday Git], linkgit:gitcvs-migration[7],
 769 linkgit:gitglossary[7], linkgit:gitcore-tutorial[7],
 770 linkgit:gitcli[7], link:user-manual.html[The Git User's Manual],
 771 linkgit:gitworkflows[7]
 772
 773 GIT
 774 ---
 775 Part of the linkgit:git[1] suite