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     [-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:v1.7.2.2/git.html[documentation for release 1.7.2.2]
  48
  49 * release notes for
  50   link:RelNotes-1.7.2.2.txt[1.7.2.2],
  51   link:RelNotes-1.7.2.1.txt[1.7.2.1],
  52   link:RelNotes-1.7.2.txt[1.7.2].
  53
  54 * link:v1.7.1.2/git.html[documentation for release 1.7.1.2]
  55
  56 * release notes for
  57   link:RelNotes-1.7.1.2.txt[1.7.1.2],
  58   link:RelNotes-1.7.1.1.txt[1.7.1.1],
  59   link:RelNotes-1.7.1.txt[1.7.1].
  60
  61 * link:v1.7.0.7/git.html[documentation for release 1.7.0.7]
  62
  63 * release notes for
  64   link:RelNotes-1.7.0.7.txt[1.7.0.7],
  65   link:RelNotes-1.7.0.6.txt[1.7.0.6],
  66   link:RelNotes-1.7.0.5.txt[1.7.0.5],
  67   link:RelNotes-1.7.0.4.txt[1.7.0.4],
  68   link:RelNotes-1.7.0.3.txt[1.7.0.3],
  69   link:RelNotes-1.7.0.2.txt[1.7.0.2],
  70   link:RelNotes-1.7.0.1.txt[1.7.0.1],
  71   link:RelNotes-1.7.0.txt[1.7.0].
  72
  73 * link:v1.6.6.2/git.html[documentation for release 1.6.6.2]
  74
  75 * release notes for
  76   link:RelNotes-1.6.6.2.txt[1.6.6.2],
  77   link:RelNotes-1.6.6.1.txt[1.6.6.1],
  78   link:RelNotes-1.6.6.txt[1.6.6].
  79
  80 * link:v1.6.5.8/git.html[documentation for release 1.6.5.8]
  81
  82 * release notes for
  83   link:RelNotes-1.6.5.8.txt[1.6.5.8],
  84   link:RelNotes-1.6.5.7.txt[1.6.5.7],
  85   link:RelNotes-1.6.5.6.txt[1.6.5.6],
  86   link:RelNotes-1.6.5.5.txt[1.6.5.5],
  87   link:RelNotes-1.6.5.4.txt[1.6.5.4],
  88   link:RelNotes-1.6.5.3.txt[1.6.5.3],
  89   link:RelNotes-1.6.5.2.txt[1.6.5.2],
  90   link:RelNotes-1.6.5.1.txt[1.6.5.1],
  91   link:RelNotes-1.6.5.txt[1.6.5].
  92
  93 * link:v1.6.4.4/git.html[documentation for release 1.6.4.4]
  94
  95 * release notes for
  96   link:RelNotes-1.6.4.4.txt[1.6.4.4],
  97   link:RelNotes-1.6.4.3.txt[1.6.4.3],
  98   link:RelNotes-1.6.4.2.txt[1.6.4.2],
  99   link:RelNotes-1.6.4.1.txt[1.6.4.1],
 100   link:RelNotes-1.6.4.txt[1.6.4].
 101
 102 * link:v1.6.3.4/git.html[documentation for release 1.6.3.4]
 103
 104 * release notes for
 105   link:RelNotes-1.6.3.4.txt[1.6.3.4],
 106   link:RelNotes-1.6.3.3.txt[1.6.3.3],
 107   link:RelNotes-1.6.3.2.txt[1.6.3.2],
 108   link:RelNotes-1.6.3.1.txt[1.6.3.1],
 109   link:RelNotes-1.6.3.txt[1.6.3].
 110
 111 * release notes for
 112   link:RelNotes-1.6.2.5.txt[1.6.2.5],
 113   link:RelNotes-1.6.2.4.txt[1.6.2.4],
 114   link:RelNotes-1.6.2.3.txt[1.6.2.3],
 115   link:RelNotes-1.6.2.2.txt[1.6.2.2],
 116   link:RelNotes-1.6.2.1.txt[1.6.2.1],
 117   link:RelNotes-1.6.2.txt[1.6.2].
 118
 119 * link:v1.6.1.3/git.html[documentation for release 1.6.1.3]
 120
 121 * release notes for
 122   link:RelNotes-1.6.1.3.txt[1.6.1.3],
 123   link:RelNotes-1.6.1.2.txt[1.6.1.2],
 124   link:RelNotes-1.6.1.1.txt[1.6.1.1],
 125   link:RelNotes-1.6.1.txt[1.6.1].
 126
 127 * link:v1.6.0.6/git.html[documentation for release 1.6.0.6]
 128
 129 * release notes for
 130   link:RelNotes-1.6.0.6.txt[1.6.0.6],
 131   link:RelNotes-1.6.0.5.txt[1.6.0.5],
 132   link:RelNotes-1.6.0.4.txt[1.6.0.4],
 133   link:RelNotes-1.6.0.3.txt[1.6.0.3],
 134   link:RelNotes-1.6.0.2.txt[1.6.0.2],
 135   link:RelNotes-1.6.0.1.txt[1.6.0.1],
 136   link:RelNotes-1.6.0.txt[1.6.0].
 137
 138 * link:v1.5.6.6/git.html[documentation for release 1.5.6.6]
 139
 140 * release notes for
 141   link:RelNotes-1.5.6.6.txt[1.5.6.6],
 142   link:RelNotes-1.5.6.5.txt[1.5.6.5],
 143   link:RelNotes-1.5.6.4.txt[1.5.6.4],
 144   link:RelNotes-1.5.6.3.txt[1.5.6.3],
 145   link:RelNotes-1.5.6.2.txt[1.5.6.2],
 146   link:RelNotes-1.5.6.1.txt[1.5.6.1],
 147   link:RelNotes-1.5.6.txt[1.5.6].
 148
 149 * link:v1.5.5.6/git.html[documentation for release 1.5.5.6]
 150
 151 * release notes for
 152   link:RelNotes-1.5.5.6.txt[1.5.5.6],
 153   link:RelNotes-1.5.5.5.txt[1.5.5.5],
 154   link:RelNotes-1.5.5.4.txt[1.5.5.4],
 155   link:RelNotes-1.5.5.3.txt[1.5.5.3],
 156   link:RelNotes-1.5.5.2.txt[1.5.5.2],
 157   link:RelNotes-1.5.5.1.txt[1.5.5.1],
 158   link:RelNotes-1.5.5.txt[1.5.5].
 159
 160 * link:v1.5.4.7/git.html[documentation for release 1.5.4.7]
 161
 162 * release notes for
 163   link:RelNotes-1.5.4.7.txt[1.5.4.7],
 164   link:RelNotes-1.5.4.6.txt[1.5.4.6],
 165   link:RelNotes-1.5.4.5.txt[1.5.4.5],
 166   link:RelNotes-1.5.4.4.txt[1.5.4.4],
 167   link:RelNotes-1.5.4.3.txt[1.5.4.3],
 168   link:RelNotes-1.5.4.2.txt[1.5.4.2],
 169   link:RelNotes-1.5.4.1.txt[1.5.4.1],
 170   link:RelNotes-1.5.4.txt[1.5.4].
 171
 172 * link:v1.5.3.8/git.html[documentation for release 1.5.3.8]
 173
 174 * release notes for
 175   link:RelNotes-1.5.3.8.txt[1.5.3.8],
 176   link:RelNotes-1.5.3.7.txt[1.5.3.7],
 177   link:RelNotes-1.5.3.6.txt[1.5.3.6],
 178   link:RelNotes-1.5.3.5.txt[1.5.3.5],
 179   link:RelNotes-1.5.3.4.txt[1.5.3.4],
 180   link:RelNotes-1.5.3.3.txt[1.5.3.3],
 181   link:RelNotes-1.5.3.2.txt[1.5.3.2],
 182   link:RelNotes-1.5.3.1.txt[1.5.3.1],
 183   link:RelNotes-1.5.3.txt[1.5.3].
 184
 185 * link:v1.5.2.5/git.html[documentation for release 1.5.2.5]
 186
 187 * release notes for
 188   link:RelNotes-1.5.2.5.txt[1.5.2.5],
 189   link:RelNotes-1.5.2.4.txt[1.5.2.4],
 190   link:RelNotes-1.5.2.3.txt[1.5.2.3],
 191   link:RelNotes-1.5.2.2.txt[1.5.2.2],
 192   link:RelNotes-1.5.2.1.txt[1.5.2.1],
 193   link:RelNotes-1.5.2.txt[1.5.2].
 194
 195 * link:v1.5.1.6/git.html[documentation for release 1.5.1.6]
 196
 197 * release notes for
 198   link:RelNotes-1.5.1.6.txt[1.5.1.6],
 199   link:RelNotes-1.5.1.5.txt[1.5.1.5],
 200   link:RelNotes-1.5.1.4.txt[1.5.1.4],
 201   link:RelNotes-1.5.1.3.txt[1.5.1.3],
 202   link:RelNotes-1.5.1.2.txt[1.5.1.2],
 203   link:RelNotes-1.5.1.1.txt[1.5.1.1],
 204   link:RelNotes-1.5.1.txt[1.5.1].
 205
 206 * link:v1.5.0.7/git.html[documentation for release 1.5.0.7]
 207
 208 * release notes for
 209   link:RelNotes-1.5.0.7.txt[1.5.0.7],
 210   link:RelNotes-1.5.0.6.txt[1.5.0.6],
 211   link:RelNotes-1.5.0.5.txt[1.5.0.5],
 212   link:RelNotes-1.5.0.3.txt[1.5.0.3],
 213   link:RelNotes-1.5.0.2.txt[1.5.0.2],
 214   link:RelNotes-1.5.0.1.txt[1.5.0.1],
 215   link:RelNotes-1.5.0.txt[1.5.0].
 216
 217 * documentation for release link:v1.4.4.4/git.html[1.4.4.4],
 218   link:v1.3.3/git.html[1.3.3],
 219   link:v1.2.6/git.html[1.2.6],
 220   link:v1.0.13/git.html[1.0.13].
 221
 222 ============
 223
 224 endif::stalenotes[]
 225
 226 OPTIONS
 227 -------
 228 --version::
 229         Prints the git suite version that the 'git' program came from.
 230
 231 --help::
 232         Prints the synopsis and a list of the most commonly used
 233         commands. If the option '--all' or '-a' is given then all
 234         available commands are printed. If a git command is named this
 235         option will bring up the manual page for that command.
 236 +
 237 Other options are available to control how the manual page is
 238 displayed. See linkgit:git-help[1] for more information,
 239 because `git --help ...` is converted internally into `git
 240 help ...`.
 241
 242 -c <name>=<value>::
 243         Pass a configuration parameter to the command. The value
 244         given will override values from configuration files.
 245         The <name> is expected in the same format as listed by
 246         'git config' (subkeys separated by dots).
 247
 248 --exec-path::
 249         Path to wherever your core git programs are installed.
 250         This can also be controlled by setting the GIT_EXEC_PATH
 251         environment variable. If no path is given, 'git' will print
 252         the current setting and then exit.
 253
 254 --html-path::
 255         Print the path to wherever your git HTML documentation is installed
 256         and exit.
 257
 258 -p::
 259 --paginate::
 260         Pipe all output into 'less' (or if set, $PAGER) if standard
 261         output is a terminal.  This overrides the `pager.<cmd>`
 262         configuration options (see the "Configuration Mechanism" section
 263         below).
 264
 265 --no-pager::
 266         Do not pipe git output into a pager.
 267
 268 --git-dir=<path>::
 269         Set the path to the repository. This can also be controlled by
 270         setting the GIT_DIR environment variable. It can be an absolute
 271         path or relative path to current working directory.
 272
 273 --work-tree=<path>::
 274         Set the path to the working tree.  The value will not be
 275         used in combination with repositories found automatically in
 276         a .git directory (i.e. $GIT_DIR is not set).
 277         This can also be controlled by setting the GIT_WORK_TREE
 278         environment variable and the core.worktree configuration
 279         variable. It can be an absolute path or relative path to
 280         the directory specified by --git-dir or GIT_DIR.
 281         Note: If --git-dir or GIT_DIR are specified but none of
 282         --work-tree, GIT_WORK_TREE and core.worktree is specified,
 283         the current working directory is regarded as the top directory
 284         of your working tree.
 285
 286 --bare::
 287         Treat the repository as a bare repository.  If GIT_DIR
 288         environment is not set, it is set to the current working
 289         directory.
 290
 291 --no-replace-objects::
 292         Do not use replacement refs to replace git objects. See
 293         linkgit:git-replace[1] for more information.
 294
 295
 296 FURTHER DOCUMENTATION
 297 ---------------------
 298
 299 See the references above to get started using git.  The following is
 300 probably more detail than necessary for a first-time user.
 301
 302 The link:user-manual.html#git-concepts[git concepts chapter of the
 303 user-manual] and linkgit:gitcore-tutorial[7] both provide
 304 introductions to the underlying git architecture.
 305
 306 See linkgit:gitworkflows[7] for an overview of recommended workflows.
 307
 308 See also the link:howto-index.html[howto] documents for some useful
 309 examples.
 310
 311 The internals are documented in the
 312 link:technical/api-index.html[GIT API documentation].
 313
 314 GIT COMMANDS
 315 ------------
 316
 317 We divide git into high level ("porcelain") commands and low level
 318 ("plumbing") commands.
 319
 320 High-level commands (porcelain)
 321 -------------------------------
 322
 323 We separate the porcelain commands into the main commands and some
 324 ancillary user utilities.
 325
 326 Main porcelain commands
 327 ~~~~~~~~~~~~~~~~~~~~~~~
 328
 329 include::cmds-mainporcelain.txt[]
 330
 331 Ancillary Commands
 332 ~~~~~~~~~~~~~~~~~~
 333 Manipulators:
 334
 335 include::cmds-ancillarymanipulators.txt[]
 336
 337 Interrogators:
 338
 339 include::cmds-ancillaryinterrogators.txt[]
 340
 341
 342 Interacting with Others
 343 ~~~~~~~~~~~~~~~~~~~~~~~
 344
 345 These commands are to interact with foreign SCM and with other
 346 people via patch over e-mail.
 347
 348 include::cmds-foreignscminterface.txt[]
 349
 350
 351 Low-level commands (plumbing)
 352 -----------------------------
 353
 354 Although git includes its
 355 own porcelain layer, its low-level commands are sufficient to support
 356 development of alternative porcelains.  Developers of such porcelains
 357 might start by reading about linkgit:git-update-index[1] and
 358 linkgit:git-read-tree[1].
 359
 360 The interface (input, output, set of options and the semantics)
 361 to these low-level commands are meant to be a lot more stable
 362 than Porcelain level commands, because these commands are
 363 primarily for scripted use.  The interface to Porcelain commands
 364 on the other hand are subject to change in order to improve the
 365 end user experience.
 366
 367 The following description divides
 368 the low-level commands into commands that manipulate objects (in
 369 the repository, index, and working tree), commands that interrogate and
 370 compare objects, and commands that move objects and references between
 371 repositories.
 372
 373
 374 Manipulation commands
 375 ~~~~~~~~~~~~~~~~~~~~~
 376
 377 include::cmds-plumbingmanipulators.txt[]
 378
 379
 380 Interrogation commands
 381 ~~~~~~~~~~~~~~~~~~~~~~
 382
 383 include::cmds-plumbinginterrogators.txt[]
 384
 385 In general, the interrogate commands do not touch the files in
 386 the working tree.
 387
 388
 389 Synching repositories
 390 ~~~~~~~~~~~~~~~~~~~~~
 391
 392 include::cmds-synchingrepositories.txt[]
 393
 394 The following are helper commands used by the above; end users
 395 typically do not use them directly.
 396
 397 include::cmds-synchelpers.txt[]
 398
 399
 400 Internal helper commands
 401 ~~~~~~~~~~~~~~~~~~~~~~~~
 402
 403 These are internal helper commands used by other commands; end
 404 users typically do not use them directly.
 405
 406 include::cmds-purehelpers.txt[]
 407
 408
 409 Configuration Mechanism
 410 -----------------------
 411
 412 Starting from 0.99.9 (actually mid 0.99.8.GIT), `.git/config` file
 413 is used to hold per-repository configuration options.  It is a
 414 simple text file modeled after `.ini` format familiar to some
 415 people.  Here is an example:
 416
 417 ------------
 418 #
 419 # A '#' or ';' character indicates a comment.
 420 #
 421
 422 ; core variables
 423 [core]
 424         ; Don't trust file modes
 425         filemode = false
 426
 427 ; user identity
 428 [user]
 429         name = "Junio C Hamano"
 430         email = "junkio@twinsun.com"
 431
 432 ------------
 433
 434 Various commands read from the configuration file and adjust
 435 their operation accordingly.  See linkgit:git-config[1] for a
 436 list.
 437
 438
 439 Identifier Terminology
 440 ----------------------
 441 <object>::
 442         Indicates the object name for any type of object.
 443
 444 <blob>::
 445         Indicates a blob object name.
 446
 447 <tree>::
 448         Indicates a tree object name.
 449
 450 <commit>::
 451         Indicates a commit object name.
 452
 453 <tree-ish>::
 454         Indicates a tree, commit or tag object name.  A
 455         command that takes a <tree-ish> argument ultimately wants to
 456         operate on a <tree> object but automatically dereferences
 457         <commit> and <tag> objects that point at a <tree>.
 458
 459 <commit-ish>::
 460         Indicates a commit or tag object name.  A
 461         command that takes a <commit-ish> argument ultimately wants to
 462         operate on a <commit> object but automatically dereferences
 463         <tag> objects that point at a <commit>.
 464
 465 <type>::
 466         Indicates that an object type is required.
 467         Currently one of: `blob`, `tree`, `commit`, or `tag`.
 468
 469 <file>::
 470         Indicates a filename - almost always relative to the
 471         root of the tree structure `GIT_INDEX_FILE` describes.
 472
 473 Symbolic Identifiers
 474 --------------------
 475 Any git command accepting any <object> can also use the following
 476 symbolic notation:
 477
 478 HEAD::
 479         indicates the head of the current branch (i.e. the
 480         contents of `$GIT_DIR/HEAD`).
 481
 482 <tag>::
 483         a valid tag 'name'
 484         (i.e. the contents of `$GIT_DIR/refs/tags/<tag>`).
 485
 486 <head>::
 487         a valid head 'name'
 488         (i.e. the contents of `$GIT_DIR/refs/heads/<head>`).
 489
 490 For a more complete list of ways to spell object names, see
 491 "SPECIFYING REVISIONS" section in linkgit:gitrevisions[1].
 492
 493
 494 File/Directory Structure
 495 ------------------------
 496
 497 Please see the linkgit:gitrepository-layout[5] document.
 498
 499 Read linkgit:githooks[5] for more details about each hook.
 500
 501 Higher level SCMs may provide and manage additional information in the
 502 `$GIT_DIR`.
 503
 504
 505 Terminology
 506 -----------
 507 Please see linkgit:gitglossary[7].
 508
 509
 510 Environment Variables
 511 ---------------------
 512 Various git commands use the following environment variables:
 513
 514 The git Repository
 515 ~~~~~~~~~~~~~~~~~~
 516 These environment variables apply to 'all' core git commands. Nb: it
 517 is worth noting that they may be used/overridden by SCMS sitting above
 518 git so take care if using Cogito etc.
 519
 520 'GIT_INDEX_FILE'::
 521         This environment allows the specification of an alternate
 522         index file. If not specified, the default of `$GIT_DIR/index`
 523         is used.
 524
 525 'GIT_OBJECT_DIRECTORY'::
 526         If the object storage directory is specified via this
 527         environment variable then the sha1 directories are created
 528         underneath - otherwise the default `$GIT_DIR/objects`
 529         directory is used.
 530
 531 'GIT_ALTERNATE_OBJECT_DIRECTORIES'::
 532         Due to the immutable nature of git objects, old objects can be
 533         archived into shared, read-only directories. This variable
 534         specifies a ":" separated (on Windows ";" separated) list
 535         of git object directories which can be used to search for git
 536         objects. New objects will not be written to these directories.
 537
 538 'GIT_DIR'::
 539         If the 'GIT_DIR' environment variable is set then it
 540         specifies a path to use instead of the default `.git`
 541         for the base of the repository.
 542
 543 'GIT_WORK_TREE'::
 544         Set the path to the working tree.  The value will not be
 545         used in combination with repositories found automatically in
 546         a .git directory (i.e. $GIT_DIR is not set).
 547         This can also be controlled by the '--work-tree' command line
 548         option and the core.worktree configuration variable.
 549
 550 'GIT_CEILING_DIRECTORIES'::
 551         This should be a colon-separated list of absolute paths.
 552         If set, it is a list of directories that git should not chdir
 553         up into while looking for a repository directory.
 554         It will not exclude the current working directory or
 555         a GIT_DIR set on the command line or in the environment.
 556         (Useful for excluding slow-loading network directories.)
 557
 558 'GIT_DISCOVERY_ACROSS_FILESYSTEM'::
 559         When run in a directory that does not have ".git" repository
 560         directory, git tries to find such a directory in the parent
 561         directories to find the top of the working tree, but by default it
 562         does not cross filesystem boundaries.  This environment variable
 563         can be set to true to tell git not to stop at filesystem
 564         boundaries.  Like 'GIT_CEILING_DIRECTORIES', this will not affect
 565         an explicit repository directory set via 'GIT_DIR' or on the
 566         command line.
 567
 568 git Commits
 569 ~~~~~~~~~~~
 570 'GIT_AUTHOR_NAME'::
 571 'GIT_AUTHOR_EMAIL'::
 572 'GIT_AUTHOR_DATE'::
 573 'GIT_COMMITTER_NAME'::
 574 'GIT_COMMITTER_EMAIL'::
 575 'GIT_COMMITTER_DATE'::
 576 'EMAIL'::
 577         see linkgit:git-commit-tree[1]
 578
 579 git Diffs
 580 ~~~~~~~~~
 581 'GIT_DIFF_OPTS'::
 582         Only valid setting is "--unified=??" or "-u??" to set the
 583         number of context lines shown when a unified diff is created.
 584         This takes precedence over any "-U" or "--unified" option
 585         value passed on the git diff command line.
 586
 587 'GIT_EXTERNAL_DIFF'::
 588         When the environment variable 'GIT_EXTERNAL_DIFF' is set, the
 589         program named by it is called, instead of the diff invocation
 590         described above.  For a path that is added, removed, or modified,
 591         'GIT_EXTERNAL_DIFF' is called with 7 parameters:
 592
 593         path old-file old-hex old-mode new-file new-hex new-mode
 594 +
 595 where:
 596
 597         <old|new>-file:: are files GIT_EXTERNAL_DIFF can use to read the
 598                          contents of <old|new>,
 599         <old|new>-hex:: are the 40-hexdigit SHA1 hashes,
 600         <old|new>-mode:: are the octal representation of the file modes.
 601
 602 +
 603 The file parameters can point at the user's working file
 604 (e.g. `new-file` in "git-diff-files"), `/dev/null` (e.g. `old-file`
 605 when a new file is added), or a temporary file (e.g. `old-file` in the
 606 index).  'GIT_EXTERNAL_DIFF' should not worry about unlinking the
 607 temporary file --- it is removed when 'GIT_EXTERNAL_DIFF' exits.
 608 +
 609 For a path that is unmerged, 'GIT_EXTERNAL_DIFF' is called with 1
 610 parameter, <path>.
 611
 612 other
 613 ~~~~~
 614 'GIT_MERGE_VERBOSITY'::
 615         A number controlling the amount of output shown by
 616         the recursive merge strategy.  Overrides merge.verbosity.
 617         See linkgit:git-merge[1]
 618
 619 'GIT_PAGER'::
 620         This environment variable overrides `$PAGER`. If it is set
 621         to an empty string or to the value "cat", git will not launch
 622         a pager.  See also the `core.pager` option in
 623         linkgit:git-config[1].
 624
 625 'GIT_SSH'::
 626         If this environment variable is set then 'git fetch'
 627         and 'git push' will use this command instead
 628         of 'ssh' when they need to connect to a remote system.
 629         The '$GIT_SSH' command will be given exactly two arguments:
 630         the 'username@host' (or just 'host') from the URL and the
 631         shell command to execute on that remote system.
 632 +
 633 To pass options to the program that you want to list in GIT_SSH
 634 you will need to wrap the program and options into a shell script,
 635 then set GIT_SSH to refer to the shell script.
 636 +
 637 Usually it is easier to configure any desired options through your
 638 personal `.ssh/config` file.  Please consult your ssh documentation
 639 for further details.
 640
 641 'GIT_FLUSH'::
 642         If this environment variable is set to "1", then commands such
 643         as 'git blame' (in incremental mode), 'git rev-list', 'git log',
 644         and 'git whatchanged' will force a flush of the output stream
 645         after each commit-oriented record have been flushed.   If this
 646         variable is set to "0", the output of these commands will be done
 647         using completely buffered I/O.   If this environment variable is
 648         not set, git will choose buffered or record-oriented flushing
 649         based on whether stdout appears to be redirected to a file or not.
 650
 651 'GIT_TRACE'::
 652         If this variable is set to "1", "2" or "true" (comparison
 653         is case insensitive), git will print `trace:` messages on
 654         stderr telling about alias expansion, built-in command
 655         execution and external command execution.
 656         If this variable is set to an integer value greater than 1
 657         and lower than 10 (strictly) then git will interpret this
 658         value as an open file descriptor and will try to write the
 659         trace messages into this file descriptor.
 660         Alternatively, if this variable is set to an absolute path
 661         (starting with a '/' character), git will interpret this
 662         as a file path and will try to write the trace messages
 663         into it.
 664
 665 Discussion[[Discussion]]
 666 ------------------------
 667
 668 More detail on the following is available from the
 669 link:user-manual.html#git-concepts[git concepts chapter of the
 670 user-manual] and linkgit:gitcore-tutorial[7].
 671
 672 A git project normally consists of a working directory with a ".git"
 673 subdirectory at the top level.  The .git directory contains, among other
 674 things, a compressed object database representing the complete history
 675 of the project, an "index" file which links that history to the current
 676 contents of the working tree, and named pointers into that history such
 677 as tags and branch heads.
 678
 679 The object database contains objects of three main types: blobs, which
 680 hold file data; trees, which point to blobs and other trees to build up
 681 directory hierarchies; and commits, which each reference a single tree
 682 and some number of parent commits.
 683
 684 The commit, equivalent to what other systems call a "changeset" or
 685 "version", represents a step in the project's history, and each parent
 686 represents an immediately preceding step.  Commits with more than one
 687 parent represent merges of independent lines of development.
 688
 689 All objects are named by the SHA1 hash of their contents, normally
 690 written as a string of 40 hex digits.  Such names are globally unique.
 691 The entire history leading up to a commit can be vouched for by signing
 692 just that commit.  A fourth object type, the tag, is provided for this
 693 purpose.
 694
 695 When first created, objects are stored in individual files, but for
 696 efficiency may later be compressed together into "pack files".
 697
 698 Named pointers called refs mark interesting points in history.  A ref
 699 may contain the SHA1 name of an object or the name of another ref.  Refs
 700 with names beginning `ref/head/` contain the SHA1 name of the most
 701 recent commit (or "head") of a branch under development.  SHA1 names of
 702 tags of interest are stored under `ref/tags/`.  A special ref named
 703 `HEAD` contains the name of the currently checked-out branch.
 704
 705 The index file is initialized with a list of all paths and, for each
 706 path, a blob object and a set of attributes.  The blob object represents
 707 the contents of the file as of the head of the current branch.  The
 708 attributes (last modified time, size, etc.) are taken from the
 709 corresponding file in the working tree.  Subsequent changes to the
 710 working tree can be found by comparing these attributes.  The index may
 711 be updated with new content, and new commits may be created from the
 712 content stored in the index.
 713
 714 The index is also capable of storing multiple entries (called "stages")
 715 for a given pathname.  These stages are used to hold the various
 716 unmerged version of a file when a merge is in progress.
 717
 718 Authors
 719 -------
 720 * git's founding father is Linus Torvalds <torvalds@osdl.org>.
 721 * The current git nurse is Junio C Hamano <gitster@pobox.com>.
 722 * The git potty was written by Andreas Ericsson <ae@op5.se>.
 723 * General upbringing is handled by the git-list <git@vger.kernel.org>.
 724
 725 Documentation
 726 --------------
 727 The documentation for git suite was started by David Greaves
 728 <david@dgreaves.com>, and later enhanced greatly by the
 729 contributors on the git-list <git@vger.kernel.org>.
 730
 731 Reporting Bugs
 732 --------------
 733
 734 Report bugs to the Git mailing list <git@vger.kernel.org> where the
 735 development and maintenance is primarily done.  You do not have to be
 736 subscribed to the list to send a message there.
 737
 738 SEE ALSO
 739 --------
 740 linkgit:gittutorial[7], linkgit:gittutorial-2[7],
 741 link:everyday.html[Everyday Git], linkgit:gitcvs-migration[7],
 742 linkgit:gitglossary[7], linkgit:gitcore-tutorial[7],
 743 linkgit:gitcli[7], link:user-manual.html[The Git User's Manual],
 744 linkgit:gitworkflows[7]
 745
 746 GIT
 747 ---
 748 Part of the linkgit:git[1] suite