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:v1.7.3.2/git.html[documentation for release 1.7.3.2]
  48
  49 * release notes for
  50   link:RelNotes/1.7.3.2.txt[1.7.3.2],
  51   link:RelNotes/1.7.3.1.txt[1.7.3.1],
  52   link:RelNotes/1.7.3.txt[1.7.3].
  53
  54 * link:v1.7.2.3/git.html[documentation for release 1.7.2.3]
  55
  56 * release notes for
  57   link:RelNotes/1.7.2.3.txt[1.7.2.3],
  58   link:RelNotes/1.7.2.2.txt[1.7.2.2],
  59   link:RelNotes/1.7.2.1.txt[1.7.2.1],
  60   link:RelNotes/1.7.2.txt[1.7.2].
  61
  62 * link:v1.7.1.2/git.html[documentation for release 1.7.1.2]
  63
  64 * release notes for
  65   link:RelNotes/1.7.1.2.txt[1.7.1.2],
  66   link:RelNotes/1.7.1.1.txt[1.7.1.1],
  67   link:RelNotes/1.7.1.txt[1.7.1].
  68
  69 * link:v1.7.0.7/git.html[documentation for release 1.7.0.7]
  70
  71 * release notes for
  72   link:RelNotes/1.7.0.7.txt[1.7.0.7],
  73   link:RelNotes/1.7.0.6.txt[1.7.0.6],
  74   link:RelNotes/1.7.0.5.txt[1.7.0.5],
  75   link:RelNotes/1.7.0.4.txt[1.7.0.4],
  76   link:RelNotes/1.7.0.3.txt[1.7.0.3],
  77   link:RelNotes/1.7.0.2.txt[1.7.0.2],
  78   link:RelNotes/1.7.0.1.txt[1.7.0.1],
  79   link:RelNotes/1.7.0.txt[1.7.0].
  80
  81 * link:v1.6.6.2/git.html[documentation for release 1.6.6.2]
  82
  83 * release notes for
  84   link:RelNotes/1.6.6.2.txt[1.6.6.2],
  85   link:RelNotes/1.6.6.1.txt[1.6.6.1],
  86   link:RelNotes/1.6.6.txt[1.6.6].
  87
  88 * link:v1.6.5.8/git.html[documentation for release 1.6.5.8]
  89
  90 * release notes for
  91   link:RelNotes/1.6.5.8.txt[1.6.5.8],
  92   link:RelNotes/1.6.5.7.txt[1.6.5.7],
  93   link:RelNotes/1.6.5.6.txt[1.6.5.6],
  94   link:RelNotes/1.6.5.5.txt[1.6.5.5],
  95   link:RelNotes/1.6.5.4.txt[1.6.5.4],
  96   link:RelNotes/1.6.5.3.txt[1.6.5.3],
  97   link:RelNotes/1.6.5.2.txt[1.6.5.2],
  98   link:RelNotes/1.6.5.1.txt[1.6.5.1],
  99   link:RelNotes/1.6.5.txt[1.6.5].
 100
 101 * link:v1.6.4.4/git.html[documentation for release 1.6.4.4]
 102
 103 * release notes for
 104   link:RelNotes/1.6.4.4.txt[1.6.4.4],
 105   link:RelNotes/1.6.4.3.txt[1.6.4.3],
 106   link:RelNotes/1.6.4.2.txt[1.6.4.2],
 107   link:RelNotes/1.6.4.1.txt[1.6.4.1],
 108   link:RelNotes/1.6.4.txt[1.6.4].
 109
 110 * link:v1.6.3.4/git.html[documentation for release 1.6.3.4]
 111
 112 * release notes for
 113   link:RelNotes/1.6.3.4.txt[1.6.3.4],
 114   link:RelNotes/1.6.3.3.txt[1.6.3.3],
 115   link:RelNotes/1.6.3.2.txt[1.6.3.2],
 116   link:RelNotes/1.6.3.1.txt[1.6.3.1],
 117   link:RelNotes/1.6.3.txt[1.6.3].
 118
 119 * release notes for
 120   link:RelNotes/1.6.2.5.txt[1.6.2.5],
 121   link:RelNotes/1.6.2.4.txt[1.6.2.4],
 122   link:RelNotes/1.6.2.3.txt[1.6.2.3],
 123   link:RelNotes/1.6.2.2.txt[1.6.2.2],
 124   link:RelNotes/1.6.2.1.txt[1.6.2.1],
 125   link:RelNotes/1.6.2.txt[1.6.2].
 126
 127 * link:v1.6.1.3/git.html[documentation for release 1.6.1.3]
 128
 129 * release notes for
 130   link:RelNotes/1.6.1.3.txt[1.6.1.3],
 131   link:RelNotes/1.6.1.2.txt[1.6.1.2],
 132   link:RelNotes/1.6.1.1.txt[1.6.1.1],
 133   link:RelNotes/1.6.1.txt[1.6.1].
 134
 135 * link:v1.6.0.6/git.html[documentation for release 1.6.0.6]
 136
 137 * release notes for
 138   link:RelNotes/1.6.0.6.txt[1.6.0.6],
 139   link:RelNotes/1.6.0.5.txt[1.6.0.5],
 140   link:RelNotes/1.6.0.4.txt[1.6.0.4],
 141   link:RelNotes/1.6.0.3.txt[1.6.0.3],
 142   link:RelNotes/1.6.0.2.txt[1.6.0.2],
 143   link:RelNotes/1.6.0.1.txt[1.6.0.1],
 144   link:RelNotes/1.6.0.txt[1.6.0].
 145
 146 * link:v1.5.6.6/git.html[documentation for release 1.5.6.6]
 147
 148 * release notes for
 149   link:RelNotes/1.5.6.6.txt[1.5.6.6],
 150   link:RelNotes/1.5.6.5.txt[1.5.6.5],
 151   link:RelNotes/1.5.6.4.txt[1.5.6.4],
 152   link:RelNotes/1.5.6.3.txt[1.5.6.3],
 153   link:RelNotes/1.5.6.2.txt[1.5.6.2],
 154   link:RelNotes/1.5.6.1.txt[1.5.6.1],
 155   link:RelNotes/1.5.6.txt[1.5.6].
 156
 157 * link:v1.5.5.6/git.html[documentation for release 1.5.5.6]
 158
 159 * release notes for
 160   link:RelNotes/1.5.5.6.txt[1.5.5.6],
 161   link:RelNotes/1.5.5.5.txt[1.5.5.5],
 162   link:RelNotes/1.5.5.4.txt[1.5.5.4],
 163   link:RelNotes/1.5.5.3.txt[1.5.5.3],
 164   link:RelNotes/1.5.5.2.txt[1.5.5.2],
 165   link:RelNotes/1.5.5.1.txt[1.5.5.1],
 166   link:RelNotes/1.5.5.txt[1.5.5].
 167
 168 * link:v1.5.4.7/git.html[documentation for release 1.5.4.7]
 169
 170 * release notes for
 171   link:RelNotes/1.5.4.7.txt[1.5.4.7],
 172   link:RelNotes/1.5.4.6.txt[1.5.4.6],
 173   link:RelNotes/1.5.4.5.txt[1.5.4.5],
 174   link:RelNotes/1.5.4.4.txt[1.5.4.4],
 175   link:RelNotes/1.5.4.3.txt[1.5.4.3],
 176   link:RelNotes/1.5.4.2.txt[1.5.4.2],
 177   link:RelNotes/1.5.4.1.txt[1.5.4.1],
 178   link:RelNotes/1.5.4.txt[1.5.4].
 179
 180 * link:v1.5.3.8/git.html[documentation for release 1.5.3.8]
 181
 182 * release notes for
 183   link:RelNotes/1.5.3.8.txt[1.5.3.8],
 184   link:RelNotes/1.5.3.7.txt[1.5.3.7],
 185   link:RelNotes/1.5.3.6.txt[1.5.3.6],
 186   link:RelNotes/1.5.3.5.txt[1.5.3.5],
 187   link:RelNotes/1.5.3.4.txt[1.5.3.4],
 188   link:RelNotes/1.5.3.3.txt[1.5.3.3],
 189   link:RelNotes/1.5.3.2.txt[1.5.3.2],
 190   link:RelNotes/1.5.3.1.txt[1.5.3.1],
 191   link:RelNotes/1.5.3.txt[1.5.3].
 192
 193 * link:v1.5.2.5/git.html[documentation for release 1.5.2.5]
 194
 195 * release notes for
 196   link:RelNotes/1.5.2.5.txt[1.5.2.5],
 197   link:RelNotes/1.5.2.4.txt[1.5.2.4],
 198   link:RelNotes/1.5.2.3.txt[1.5.2.3],
 199   link:RelNotes/1.5.2.2.txt[1.5.2.2],
 200   link:RelNotes/1.5.2.1.txt[1.5.2.1],
 201   link:RelNotes/1.5.2.txt[1.5.2].
 202
 203 * link:v1.5.1.6/git.html[documentation for release 1.5.1.6]
 204
 205 * release notes for
 206   link:RelNotes/1.5.1.6.txt[1.5.1.6],
 207   link:RelNotes/1.5.1.5.txt[1.5.1.5],
 208   link:RelNotes/1.5.1.4.txt[1.5.1.4],
 209   link:RelNotes/1.5.1.3.txt[1.5.1.3],
 210   link:RelNotes/1.5.1.2.txt[1.5.1.2],
 211   link:RelNotes/1.5.1.1.txt[1.5.1.1],
 212   link:RelNotes/1.5.1.txt[1.5.1].
 213
 214 * link:v1.5.0.7/git.html[documentation for release 1.5.0.7]
 215
 216 * release notes for
 217   link:RelNotes/1.5.0.7.txt[1.5.0.7],
 218   link:RelNotes/1.5.0.6.txt[1.5.0.6],
 219   link:RelNotes/1.5.0.5.txt[1.5.0.5],
 220   link:RelNotes/1.5.0.3.txt[1.5.0.3],
 221   link:RelNotes/1.5.0.2.txt[1.5.0.2],
 222   link:RelNotes/1.5.0.1.txt[1.5.0.1],
 223   link:RelNotes/1.5.0.txt[1.5.0].
 224
 225 * documentation for release link:v1.4.4.4/git.html[1.4.4.4],
 226   link:v1.3.3/git.html[1.3.3],
 227   link:v1.2.6/git.html[1.2.6],
 228   link:v1.0.13/git.html[1.0.13].
 229
 230 ============
 231
 232 endif::stalenotes[]
 233
 234 OPTIONS
 235 -------
 236 --version::
 237         Prints the git suite version that the 'git' program came from.
 238
 239 --help::
 240         Prints the synopsis and a list of the most commonly used
 241         commands. If the option '--all' or '-a' is given then all
 242         available commands are printed. If a git command is named this
 243         option will bring up the manual page for that command.
 244 +
 245 Other options are available to control how the manual page is
 246 displayed. See linkgit:git-help[1] for more information,
 247 because `git --help ...` is converted internally into `git
 248 help ...`.
 249
 250 -c <name>=<value>::
 251         Pass a configuration parameter to the command. The value
 252         given will override values from configuration files.
 253         The <name> is expected in the same format as listed by
 254         'git config' (subkeys separated by dots).
 255
 256 --exec-path[=<path>]::
 257         Path to wherever your core git programs are installed.
 258         This can also be controlled by setting the GIT_EXEC_PATH
 259         environment variable. If no path is given, 'git' will print
 260         the current setting and then exit.
 261
 262 --html-path::
 263         Print the path to wherever your git HTML documentation is installed
 264         and exit.
 265
 266 -p::
 267 --paginate::
 268         Pipe all output into 'less' (or if set, $PAGER) if standard
 269         output is a terminal.  This overrides the `pager.<cmd>`
 270         configuration options (see the "Configuration Mechanism" section
 271         below).
 272
 273 --no-pager::
 274         Do not pipe git output into a pager.
 275
 276 --git-dir=<path>::
 277         Set the path to the repository. This can also be controlled by
 278         setting the GIT_DIR environment variable. It can be an absolute
 279         path or relative path to current working directory.
 280
 281 --work-tree=<path>::
 282         Set the path to the working tree.  The value will not be
 283         used in combination with repositories found automatically in
 284         a .git directory (i.e. $GIT_DIR is not set).
 285         This can also be controlled by setting the GIT_WORK_TREE
 286         environment variable and the core.worktree configuration
 287         variable. It can be an absolute path or relative path to
 288         the directory specified by --git-dir or GIT_DIR.
 289         Note: If --git-dir or GIT_DIR are specified but none of
 290         --work-tree, GIT_WORK_TREE and core.worktree is specified,
 291         the current working directory is regarded as the top directory
 292         of your working tree.
 293
 294 --bare::
 295         Treat the repository as a bare repository.  If GIT_DIR
 296         environment is not set, it is set to the current working
 297         directory.
 298
 299 --no-replace-objects::
 300         Do not use replacement refs to replace git objects. See
 301         linkgit:git-replace[1] for more information.
 302
 303
 304 FURTHER DOCUMENTATION
 305 ---------------------
 306
 307 See the references above to get started using git.  The following is
 308 probably more detail than necessary for a first-time user.
 309
 310 The link:user-manual.html#git-concepts[git concepts chapter of the
 311 user-manual] and linkgit:gitcore-tutorial[7] both provide
 312 introductions to the underlying git architecture.
 313
 314 See linkgit:gitworkflows[7] for an overview of recommended workflows.
 315
 316 See also the link:howto-index.html[howto] documents for some useful
 317 examples.
 318
 319 The internals are documented in the
 320 link:technical/api-index.html[GIT API documentation].
 321
 322 GIT COMMANDS
 323 ------------
 324
 325 We divide git into high level ("porcelain") commands and low level
 326 ("plumbing") commands.
 327
 328 High-level commands (porcelain)
 329 -------------------------------
 330
 331 We separate the porcelain commands into the main commands and some
 332 ancillary user utilities.
 333
 334 Main porcelain commands
 335 ~~~~~~~~~~~~~~~~~~~~~~~
 336
 337 include::cmds-mainporcelain.txt[]
 338
 339 Ancillary Commands
 340 ~~~~~~~~~~~~~~~~~~
 341 Manipulators:
 342
 343 include::cmds-ancillarymanipulators.txt[]
 344
 345 Interrogators:
 346
 347 include::cmds-ancillaryinterrogators.txt[]
 348
 349
 350 Interacting with Others
 351 ~~~~~~~~~~~~~~~~~~~~~~~
 352
 353 These commands are to interact with foreign SCM and with other
 354 people via patch over e-mail.
 355
 356 include::cmds-foreignscminterface.txt[]
 357
 358
 359 Low-level commands (plumbing)
 360 -----------------------------
 361
 362 Although git includes its
 363 own porcelain layer, its low-level commands are sufficient to support
 364 development of alternative porcelains.  Developers of such porcelains
 365 might start by reading about linkgit:git-update-index[1] and
 366 linkgit:git-read-tree[1].
 367
 368 The interface (input, output, set of options and the semantics)
 369 to these low-level commands are meant to be a lot more stable
 370 than Porcelain level commands, because these commands are
 371 primarily for scripted use.  The interface to Porcelain commands
 372 on the other hand are subject to change in order to improve the
 373 end user experience.
 374
 375 The following description divides
 376 the low-level commands into commands that manipulate objects (in
 377 the repository, index, and working tree), commands that interrogate and
 378 compare objects, and commands that move objects and references between
 379 repositories.
 380
 381
 382 Manipulation commands
 383 ~~~~~~~~~~~~~~~~~~~~~
 384
 385 include::cmds-plumbingmanipulators.txt[]
 386
 387
 388 Interrogation commands
 389 ~~~~~~~~~~~~~~~~~~~~~~
 390
 391 include::cmds-plumbinginterrogators.txt[]
 392
 393 In general, the interrogate commands do not touch the files in
 394 the working tree.
 395
 396
 397 Synching repositories
 398 ~~~~~~~~~~~~~~~~~~~~~
 399
 400 include::cmds-synchingrepositories.txt[]
 401
 402 The following are helper commands used by the above; end users
 403 typically do not use them directly.
 404
 405 include::cmds-synchelpers.txt[]
 406
 407
 408 Internal helper commands
 409 ~~~~~~~~~~~~~~~~~~~~~~~~
 410
 411 These are internal helper commands used by other commands; end
 412 users typically do not use them directly.
 413
 414 include::cmds-purehelpers.txt[]
 415
 416
 417 Configuration Mechanism
 418 -----------------------
 419
 420 Starting from 0.99.9 (actually mid 0.99.8.GIT), `.git/config` file
 421 is used to hold per-repository configuration options.  It is a
 422 simple text file modeled after `.ini` format familiar to some
 423 people.  Here is an example:
 424
 425 ------------
 426 #
 427 # A '#' or ';' character indicates a comment.
 428 #
 429
 430 ; core variables
 431 [core]
 432         ; Don't trust file modes
 433         filemode = false
 434
 435 ; user identity
 436 [user]
 437         name = "Junio C Hamano"
 438         email = "junkio@twinsun.com"
 439
 440 ------------
 441
 442 Various commands read from the configuration file and adjust
 443 their operation accordingly.  See linkgit:git-config[1] for a
 444 list.
 445
 446
 447 Identifier Terminology
 448 ----------------------
 449 <object>::
 450         Indicates the object name for any type of object.
 451
 452 <blob>::
 453         Indicates a blob object name.
 454
 455 <tree>::
 456         Indicates a tree object name.
 457
 458 <commit>::
 459         Indicates a commit object name.
 460
 461 <tree-ish>::
 462         Indicates a tree, commit or tag object name.  A
 463         command that takes a <tree-ish> argument ultimately wants to
 464         operate on a <tree> object but automatically dereferences
 465         <commit> and <tag> objects that point at a <tree>.
 466
 467 <commit-ish>::
 468         Indicates a commit or tag object name.  A
 469         command that takes a <commit-ish> argument ultimately wants to
 470         operate on a <commit> object but automatically dereferences
 471         <tag> objects that point at a <commit>.
 472
 473 <type>::
 474         Indicates that an object type is required.
 475         Currently one of: `blob`, `tree`, `commit`, or `tag`.
 476
 477 <file>::
 478         Indicates a filename - almost always relative to the
 479         root of the tree structure `GIT_INDEX_FILE` describes.
 480
 481 Symbolic Identifiers
 482 --------------------
 483 Any git command accepting any <object> can also use the following
 484 symbolic notation:
 485
 486 HEAD::
 487         indicates the head of the current branch (i.e. the
 488         contents of `$GIT_DIR/HEAD`).
 489
 490 <tag>::
 491         a valid tag 'name'
 492         (i.e. the contents of `$GIT_DIR/refs/tags/<tag>`).
 493
 494 <head>::
 495         a valid head 'name'
 496         (i.e. the contents of `$GIT_DIR/refs/heads/<head>`).
 497
 498 For a more complete list of ways to spell object names, see
 499 "SPECIFYING REVISIONS" section in linkgit:gitrevisions[7].
 500
 501
 502 File/Directory Structure
 503 ------------------------
 504
 505 Please see the linkgit:gitrepository-layout[5] document.
 506
 507 Read linkgit:githooks[5] for more details about each hook.
 508
 509 Higher level SCMs may provide and manage additional information in the
 510 `$GIT_DIR`.
 511
 512
 513 Terminology
 514 -----------
 515 Please see linkgit:gitglossary[7].
 516
 517
 518 Environment Variables
 519 ---------------------
 520 Various git commands use the following environment variables:
 521
 522 The git Repository
 523 ~~~~~~~~~~~~~~~~~~
 524 These environment variables apply to 'all' core git commands. Nb: it
 525 is worth noting that they may be used/overridden by SCMS sitting above
 526 git so take care if using Cogito etc.
 527
 528 'GIT_INDEX_FILE'::
 529         This environment allows the specification of an alternate
 530         index file. If not specified, the default of `$GIT_DIR/index`
 531         is used.
 532
 533 'GIT_OBJECT_DIRECTORY'::
 534         If the object storage directory is specified via this
 535         environment variable then the sha1 directories are created
 536         underneath - otherwise the default `$GIT_DIR/objects`
 537         directory is used.
 538
 539 'GIT_ALTERNATE_OBJECT_DIRECTORIES'::
 540         Due to the immutable nature of git objects, old objects can be
 541         archived into shared, read-only directories. This variable
 542         specifies a ":" separated (on Windows ";" separated) list
 543         of git object directories which can be used to search for git
 544         objects. New objects will not be written to these directories.
 545
 546 'GIT_DIR'::
 547         If the 'GIT_DIR' environment variable is set then it
 548         specifies a path to use instead of the default `.git`
 549         for the base of the repository.
 550
 551 'GIT_WORK_TREE'::
 552         Set the path to the working tree.  The value will not be
 553         used in combination with repositories found automatically in
 554         a .git directory (i.e. $GIT_DIR is not set).
 555         This can also be controlled by the '--work-tree' command line
 556         option and the core.worktree configuration variable.
 557
 558 'GIT_CEILING_DIRECTORIES'::
 559         This should be a colon-separated list of absolute paths.
 560         If set, it is a list of directories that git should not chdir
 561         up into while looking for a repository directory.
 562         It will not exclude the current working directory or
 563         a GIT_DIR set on the command line or in the environment.
 564         (Useful for excluding slow-loading network directories.)
 565
 566 'GIT_DISCOVERY_ACROSS_FILESYSTEM'::
 567         When run in a directory that does not have ".git" repository
 568         directory, git tries to find such a directory in the parent
 569         directories to find the top of the working tree, but by default it
 570         does not cross filesystem boundaries.  This environment variable
 571         can be set to true to tell git not to stop at filesystem
 572         boundaries.  Like 'GIT_CEILING_DIRECTORIES', this will not affect
 573         an explicit repository directory set via 'GIT_DIR' or on the
 574         command line.
 575
 576 git Commits
 577 ~~~~~~~~~~~
 578 'GIT_AUTHOR_NAME'::
 579 'GIT_AUTHOR_EMAIL'::
 580 'GIT_AUTHOR_DATE'::
 581 'GIT_COMMITTER_NAME'::
 582 'GIT_COMMITTER_EMAIL'::
 583 'GIT_COMMITTER_DATE'::
 584 'EMAIL'::
 585         see linkgit:git-commit-tree[1]
 586
 587 git Diffs
 588 ~~~~~~~~~
 589 'GIT_DIFF_OPTS'::
 590         Only valid setting is "--unified=??" or "-u??" to set the
 591         number of context lines shown when a unified diff is created.
 592         This takes precedence over any "-U" or "--unified" option
 593         value passed on the git diff command line.
 594
 595 'GIT_EXTERNAL_DIFF'::
 596         When the environment variable 'GIT_EXTERNAL_DIFF' is set, the
 597         program named by it is called, instead of the diff invocation
 598         described above.  For a path that is added, removed, or modified,
 599         'GIT_EXTERNAL_DIFF' is called with 7 parameters:
 600
 601         path old-file old-hex old-mode new-file new-hex new-mode
 602 +
 603 where:
 604
 605         <old|new>-file:: are files GIT_EXTERNAL_DIFF can use to read the
 606                          contents of <old|new>,
 607         <old|new>-hex:: are the 40-hexdigit SHA1 hashes,
 608         <old|new>-mode:: are the octal representation of the file modes.
 609
 610 +
 611 The file parameters can point at the user's working file
 612 (e.g. `new-file` in "git-diff-files"), `/dev/null` (e.g. `old-file`
 613 when a new file is added), or a temporary file (e.g. `old-file` in the
 614 index).  'GIT_EXTERNAL_DIFF' should not worry about unlinking the
 615 temporary file --- it is removed when 'GIT_EXTERNAL_DIFF' exits.
 616 +
 617 For a path that is unmerged, 'GIT_EXTERNAL_DIFF' is called with 1
 618 parameter, <path>.
 619
 620 other
 621 ~~~~~
 622 'GIT_MERGE_VERBOSITY'::
 623         A number controlling the amount of output shown by
 624         the recursive merge strategy.  Overrides merge.verbosity.
 625         See linkgit:git-merge[1]
 626
 627 'GIT_PAGER'::
 628         This environment variable overrides `$PAGER`. If it is set
 629         to an empty string or to the value "cat", git will not launch
 630         a pager.  See also the `core.pager` option in
 631         linkgit:git-config[1].
 632
 633 'GIT_SSH'::
 634         If this environment variable is set then 'git fetch'
 635         and 'git push' will use this command instead
 636         of 'ssh' when they need to connect to a remote system.
 637         The '$GIT_SSH' command will be given exactly two arguments:
 638         the 'username@host' (or just 'host') from the URL and the
 639         shell command to execute on that remote system.
 640 +
 641 To pass options to the program that you want to list in GIT_SSH
 642 you will need to wrap the program and options into a shell script,
 643 then set GIT_SSH to refer to the shell script.
 644 +
 645 Usually it is easier to configure any desired options through your
 646 personal `.ssh/config` file.  Please consult your ssh documentation
 647 for further details.
 648
 649 'GIT_ASKPASS'::
 650         If this environment variable is set, then git commands which need to
 651         acquire passwords or passphrases (e.g. for HTTP or IMAP authentication)
 652         will call this program with a suitable prompt as command line argument
 653         and read the password from its STDOUT. See also the 'core.askpass'
 654         option in linkgit:git-config[1].
 655
 656 'GIT_FLUSH'::
 657         If this environment variable is set to "1", then commands such
 658         as 'git blame' (in incremental mode), 'git rev-list', 'git log',
 659         and 'git whatchanged' will force a flush of the output stream
 660         after each commit-oriented record have been flushed.   If this
 661         variable is set to "0", the output of these commands will be done
 662         using completely buffered I/O.   If this environment variable is
 663         not set, git will choose buffered or record-oriented flushing
 664         based on whether stdout appears to be redirected to a file or not.
 665
 666 'GIT_TRACE'::
 667         If this variable is set to "1", "2" or "true" (comparison
 668         is case insensitive), git will print `trace:` messages on
 669         stderr telling about alias expansion, built-in command
 670         execution and external command execution.
 671         If this variable is set to an integer value greater than 1
 672         and lower than 10 (strictly) then git will interpret this
 673         value as an open file descriptor and will try to write the
 674         trace messages into this file descriptor.
 675         Alternatively, if this variable is set to an absolute path
 676         (starting with a '/' character), git will interpret this
 677         as a file path and will try to write the trace messages
 678         into it.
 679
 680 Discussion[[Discussion]]
 681 ------------------------
 682
 683 More detail on the following is available from the
 684 link:user-manual.html#git-concepts[git concepts chapter of the
 685 user-manual] and linkgit:gitcore-tutorial[7].
 686
 687 A git project normally consists of a working directory with a ".git"
 688 subdirectory at the top level.  The .git directory contains, among other
 689 things, a compressed object database representing the complete history
 690 of the project, an "index" file which links that history to the current
 691 contents of the working tree, and named pointers into that history such
 692 as tags and branch heads.
 693
 694 The object database contains objects of three main types: blobs, which
 695 hold file data; trees, which point to blobs and other trees to build up
 696 directory hierarchies; and commits, which each reference a single tree
 697 and some number of parent commits.
 698
 699 The commit, equivalent to what other systems call a "changeset" or
 700 "version", represents a step in the project's history, and each parent
 701 represents an immediately preceding step.  Commits with more than one
 702 parent represent merges of independent lines of development.
 703
 704 All objects are named by the SHA1 hash of their contents, normally
 705 written as a string of 40 hex digits.  Such names are globally unique.
 706 The entire history leading up to a commit can be vouched for by signing
 707 just that commit.  A fourth object type, the tag, is provided for this
 708 purpose.
 709
 710 When first created, objects are stored in individual files, but for
 711 efficiency may later be compressed together into "pack files".
 712
 713 Named pointers called refs mark interesting points in history.  A ref
 714 may contain the SHA1 name of an object or the name of another ref.  Refs
 715 with names beginning `ref/head/` contain the SHA1 name of the most
 716 recent commit (or "head") of a branch under development.  SHA1 names of
 717 tags of interest are stored under `ref/tags/`.  A special ref named
 718 `HEAD` contains the name of the currently checked-out branch.
 719
 720 The index file is initialized with a list of all paths and, for each
 721 path, a blob object and a set of attributes.  The blob object represents
 722 the contents of the file as of the head of the current branch.  The
 723 attributes (last modified time, size, etc.) are taken from the
 724 corresponding file in the working tree.  Subsequent changes to the
 725 working tree can be found by comparing these attributes.  The index may
 726 be updated with new content, and new commits may be created from the
 727 content stored in the index.
 728
 729 The index is also capable of storing multiple entries (called "stages")
 730 for a given pathname.  These stages are used to hold the various
 731 unmerged version of a file when a merge is in progress.
 732
 733 Authors
 734 -------
 735 * git's founding father is Linus Torvalds <torvalds@osdl.org>.
 736 * The current git nurse is Junio C Hamano <gitster@pobox.com>.
 737 * The git potty was written by Andreas Ericsson <ae@op5.se>.
 738 * General upbringing is handled by the git-list <git@vger.kernel.org>.
 739
 740 Documentation
 741 --------------
 742 The documentation for git suite was started by David Greaves
 743 <david@dgreaves.com>, and later enhanced greatly by the
 744 contributors on the git-list <git@vger.kernel.org>.
 745
 746 Reporting Bugs
 747 --------------
 748
 749 Report bugs to the Git mailing list <git@vger.kernel.org> where the
 750 development and maintenance is primarily done.  You do not have to be
 751 subscribed to the list to send a message there.
 752
 753 SEE ALSO
 754 --------
 755 linkgit:gittutorial[7], linkgit:gittutorial-2[7],
 756 link:everyday.html[Everyday Git], linkgit:gitcvs-migration[7],
 757 linkgit:gitglossary[7], linkgit:gitcore-tutorial[7],
 758 linkgit:gitcli[7], link:user-manual.html[The Git User's Manual],
 759 linkgit:gitworkflows[7]
 760
 761 GIT
 762 ---
 763 Part of the linkgit:git[1] suite