Documentation / git.txton commit revisions: allow --glob and friends in parse_options-enabled commands (0fc63ec)
   1git(1)
   2======
   3
   4NAME
   5----
   6git - the stupid content tracker
   7
   8
   9SYNOPSIS
  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
  18DESCRIPTION
  19-----------
  20Git is a fast, scalable, distributed revision control system with an
  21unusually rich command set that provides both high-level operations
  22and full access to internals.
  23
  24See linkgit:gittutorial[7] to get started, then see
  25link:everyday.html[Everyday Git] for a useful minimum set of commands, and
  26"man git-commandname" for documentation of each command.  CVS users may
  27also want to read linkgit:gitcvs-migration[7].  See
  28the link:user-manual.html[Git User's Manual] for a more in-depth
  29introduction.
  30
  31The '<command>' is either a name of a Git command (see below) or an alias
  32as defined in the configuration file (see linkgit:git-config[1]).
  33
  34Formatted and hyperlinked version of the latest git
  35documentation can be viewed at
  36`http://www.kernel.org/pub/software/scm/git/docs/`.
  37
  38ifdef::stalenotes[]
  39[NOTE]
  40============
  41
  42You are reading the documentation for the latest (possibly
  43unreleased) version of git, that is available from 'master'
  44branch of the `git.git` repository.
  45Documentation for older releases are available here:
  46
  47* link:v1.7.4.5/git.html[documentation for release 1.7.4.5]
  48
  49* release notes for
  50  link:RelNotes/1.7.4.5.txt[1.7.4.5],
  51  link:RelNotes/1.7.4.4.txt[1.7.4.4],
  52  link:RelNotes/1.7.4.3.txt[1.7.4.3],
  53  link:RelNotes/1.7.4.2.txt[1.7.4.2],
  54  link:RelNotes/1.7.4.1.txt[1.7.4.1],
  55  link:RelNotes/1.7.4.txt[1.7.4].
  56
  57* link:v1.7.3.5/git.html[documentation for release 1.7.3.5]
  58
  59* release notes for
  60  link:RelNotes/1.7.3.5.txt[1.7.3.5],
  61  link:RelNotes/1.7.3.4.txt[1.7.3.4],
  62  link:RelNotes/1.7.3.3.txt[1.7.3.3],
  63  link:RelNotes/1.7.3.2.txt[1.7.3.2],
  64  link:RelNotes/1.7.3.1.txt[1.7.3.1],
  65  link:RelNotes/1.7.3.txt[1.7.3].
  66
  67* link:v1.7.2.5/git.html[documentation for release 1.7.2.5]
  68
  69* release notes for
  70  link:RelNotes/1.7.2.5.txt[1.7.2.5],
  71  link:RelNotes/1.7.2.4.txt[1.7.2.4],
  72  link:RelNotes/1.7.2.3.txt[1.7.2.3],
  73  link:RelNotes/1.7.2.2.txt[1.7.2.2],
  74  link:RelNotes/1.7.2.1.txt[1.7.2.1],
  75  link:RelNotes/1.7.2.txt[1.7.2].
  76
  77* link:v1.7.1.4/git.html[documentation for release 1.7.1.4]
  78
  79* release notes for
  80  link:RelNotes/1.7.1.4.txt[1.7.1.4],
  81  link:RelNotes/1.7.1.3.txt[1.7.1.3],
  82  link:RelNotes/1.7.1.2.txt[1.7.1.2],
  83  link:RelNotes/1.7.1.1.txt[1.7.1.1],
  84  link:RelNotes/1.7.1.txt[1.7.1].
  85
  86* link:v1.7.0.9/git.html[documentation for release 1.7.0.9]
  87
  88* release notes for
  89  link:RelNotes/1.7.0.9.txt[1.7.0.9],
  90  link:RelNotes/1.7.0.8.txt[1.7.0.8],
  91  link:RelNotes/1.7.0.7.txt[1.7.0.7],
  92  link:RelNotes/1.7.0.6.txt[1.7.0.6],
  93  link:RelNotes/1.7.0.5.txt[1.7.0.5],
  94  link:RelNotes/1.7.0.4.txt[1.7.0.4],
  95  link:RelNotes/1.7.0.3.txt[1.7.0.3],
  96  link:RelNotes/1.7.0.2.txt[1.7.0.2],
  97  link:RelNotes/1.7.0.1.txt[1.7.0.1],
  98  link:RelNotes/1.7.0.txt[1.7.0].
  99
 100* link:v1.6.6.3/git.html[documentation for release 1.6.6.3]
 101
 102* release notes for
 103  link:RelNotes/1.6.6.3.txt[1.6.6.3],
 104  link:RelNotes/1.6.6.2.txt[1.6.6.2],
 105  link:RelNotes/1.6.6.1.txt[1.6.6.1],
 106  link:RelNotes/1.6.6.txt[1.6.6].
 107
 108* link:v1.6.5.9/git.html[documentation for release 1.6.5.9]
 109
 110* release notes for
 111  link:RelNotes/1.6.5.9.txt[1.6.5.9],
 112  link:RelNotes/1.6.5.8.txt[1.6.5.8],
 113  link:RelNotes/1.6.5.7.txt[1.6.5.7],
 114  link:RelNotes/1.6.5.6.txt[1.6.5.6],
 115  link:RelNotes/1.6.5.5.txt[1.6.5.5],
 116  link:RelNotes/1.6.5.4.txt[1.6.5.4],
 117  link:RelNotes/1.6.5.3.txt[1.6.5.3],
 118  link:RelNotes/1.6.5.2.txt[1.6.5.2],
 119  link:RelNotes/1.6.5.1.txt[1.6.5.1],
 120  link:RelNotes/1.6.5.txt[1.6.5].
 121
 122* link:v1.6.4.5/git.html[documentation for release 1.6.4.5]
 123
 124* release notes for
 125  link:RelNotes/1.6.4.5.txt[1.6.4.5],
 126  link:RelNotes/1.6.4.4.txt[1.6.4.4],
 127  link:RelNotes/1.6.4.3.txt[1.6.4.3],
 128  link:RelNotes/1.6.4.2.txt[1.6.4.2],
 129  link:RelNotes/1.6.4.1.txt[1.6.4.1],
 130  link:RelNotes/1.6.4.txt[1.6.4].
 131
 132* link:v1.6.3.4/git.html[documentation for release 1.6.3.4]
 133
 134* release notes for
 135  link:RelNotes/1.6.3.4.txt[1.6.3.4],
 136  link:RelNotes/1.6.3.3.txt[1.6.3.3],
 137  link:RelNotes/1.6.3.2.txt[1.6.3.2],
 138  link:RelNotes/1.6.3.1.txt[1.6.3.1],
 139  link:RelNotes/1.6.3.txt[1.6.3].
 140
 141* release notes for
 142  link:RelNotes/1.6.2.5.txt[1.6.2.5],
 143  link:RelNotes/1.6.2.4.txt[1.6.2.4],
 144  link:RelNotes/1.6.2.3.txt[1.6.2.3],
 145  link:RelNotes/1.6.2.2.txt[1.6.2.2],
 146  link:RelNotes/1.6.2.1.txt[1.6.2.1],
 147  link:RelNotes/1.6.2.txt[1.6.2].
 148
 149* link:v1.6.1.3/git.html[documentation for release 1.6.1.3]
 150
 151* release notes for
 152  link:RelNotes/1.6.1.3.txt[1.6.1.3],
 153  link:RelNotes/1.6.1.2.txt[1.6.1.2],
 154  link:RelNotes/1.6.1.1.txt[1.6.1.1],
 155  link:RelNotes/1.6.1.txt[1.6.1].
 156
 157* link:v1.6.0.6/git.html[documentation for release 1.6.0.6]
 158
 159* release notes for
 160  link:RelNotes/1.6.0.6.txt[1.6.0.6],
 161  link:RelNotes/1.6.0.5.txt[1.6.0.5],
 162  link:RelNotes/1.6.0.4.txt[1.6.0.4],
 163  link:RelNotes/1.6.0.3.txt[1.6.0.3],
 164  link:RelNotes/1.6.0.2.txt[1.6.0.2],
 165  link:RelNotes/1.6.0.1.txt[1.6.0.1],
 166  link:RelNotes/1.6.0.txt[1.6.0].
 167
 168* link:v1.5.6.6/git.html[documentation for release 1.5.6.6]
 169
 170* release notes for
 171  link:RelNotes/1.5.6.6.txt[1.5.6.6],
 172  link:RelNotes/1.5.6.5.txt[1.5.6.5],
 173  link:RelNotes/1.5.6.4.txt[1.5.6.4],
 174  link:RelNotes/1.5.6.3.txt[1.5.6.3],
 175  link:RelNotes/1.5.6.2.txt[1.5.6.2],
 176  link:RelNotes/1.5.6.1.txt[1.5.6.1],
 177  link:RelNotes/1.5.6.txt[1.5.6].
 178
 179* link:v1.5.5.6/git.html[documentation for release 1.5.5.6]
 180
 181* release notes for
 182  link:RelNotes/1.5.5.6.txt[1.5.5.6],
 183  link:RelNotes/1.5.5.5.txt[1.5.5.5],
 184  link:RelNotes/1.5.5.4.txt[1.5.5.4],
 185  link:RelNotes/1.5.5.3.txt[1.5.5.3],
 186  link:RelNotes/1.5.5.2.txt[1.5.5.2],
 187  link:RelNotes/1.5.5.1.txt[1.5.5.1],
 188  link:RelNotes/1.5.5.txt[1.5.5].
 189
 190* link:v1.5.4.7/git.html[documentation for release 1.5.4.7]
 191
 192* release notes for
 193  link:RelNotes/1.5.4.7.txt[1.5.4.7],
 194  link:RelNotes/1.5.4.6.txt[1.5.4.6],
 195  link:RelNotes/1.5.4.5.txt[1.5.4.5],
 196  link:RelNotes/1.5.4.4.txt[1.5.4.4],
 197  link:RelNotes/1.5.4.3.txt[1.5.4.3],
 198  link:RelNotes/1.5.4.2.txt[1.5.4.2],
 199  link:RelNotes/1.5.4.1.txt[1.5.4.1],
 200  link:RelNotes/1.5.4.txt[1.5.4].
 201
 202* link:v1.5.3.8/git.html[documentation for release 1.5.3.8]
 203
 204* release notes for
 205  link:RelNotes/1.5.3.8.txt[1.5.3.8],
 206  link:RelNotes/1.5.3.7.txt[1.5.3.7],
 207  link:RelNotes/1.5.3.6.txt[1.5.3.6],
 208  link:RelNotes/1.5.3.5.txt[1.5.3.5],
 209  link:RelNotes/1.5.3.4.txt[1.5.3.4],
 210  link:RelNotes/1.5.3.3.txt[1.5.3.3],
 211  link:RelNotes/1.5.3.2.txt[1.5.3.2],
 212  link:RelNotes/1.5.3.1.txt[1.5.3.1],
 213  link:RelNotes/1.5.3.txt[1.5.3].
 214
 215* link:v1.5.2.5/git.html[documentation for release 1.5.2.5]
 216
 217* release notes for
 218  link:RelNotes/1.5.2.5.txt[1.5.2.5],
 219  link:RelNotes/1.5.2.4.txt[1.5.2.4],
 220  link:RelNotes/1.5.2.3.txt[1.5.2.3],
 221  link:RelNotes/1.5.2.2.txt[1.5.2.2],
 222  link:RelNotes/1.5.2.1.txt[1.5.2.1],
 223  link:RelNotes/1.5.2.txt[1.5.2].
 224
 225* link:v1.5.1.6/git.html[documentation for release 1.5.1.6]
 226
 227* release notes for
 228  link:RelNotes/1.5.1.6.txt[1.5.1.6],
 229  link:RelNotes/1.5.1.5.txt[1.5.1.5],
 230  link:RelNotes/1.5.1.4.txt[1.5.1.4],
 231  link:RelNotes/1.5.1.3.txt[1.5.1.3],
 232  link:RelNotes/1.5.1.2.txt[1.5.1.2],
 233  link:RelNotes/1.5.1.1.txt[1.5.1.1],
 234  link:RelNotes/1.5.1.txt[1.5.1].
 235
 236* link:v1.5.0.7/git.html[documentation for release 1.5.0.7]
 237
 238* release notes for
 239  link:RelNotes/1.5.0.7.txt[1.5.0.7],
 240  link:RelNotes/1.5.0.6.txt[1.5.0.6],
 241  link:RelNotes/1.5.0.5.txt[1.5.0.5],
 242  link:RelNotes/1.5.0.3.txt[1.5.0.3],
 243  link:RelNotes/1.5.0.2.txt[1.5.0.2],
 244  link:RelNotes/1.5.0.1.txt[1.5.0.1],
 245  link:RelNotes/1.5.0.txt[1.5.0].
 246
 247* documentation for release link:v1.4.4.4/git.html[1.4.4.4],
 248  link:v1.3.3/git.html[1.3.3],
 249  link:v1.2.6/git.html[1.2.6],
 250  link:v1.0.13/git.html[1.0.13].
 251
 252============
 253
 254endif::stalenotes[]
 255
 256OPTIONS
 257-------
 258--version::
 259        Prints the git suite version that the 'git' program came from.
 260
 261--help::
 262        Prints the synopsis and a list of the most commonly used
 263        commands. If the option '--all' or '-a' is given then all
 264        available commands are printed. If a git command is named this
 265        option will bring up the manual page for that command.
 266+
 267Other options are available to control how the manual page is
 268displayed. See linkgit:git-help[1] for more information,
 269because `git --help ...` is converted internally into `git
 270help ...`.
 271
 272-c <name>=<value>::
 273        Pass a configuration parameter to the command. The value
 274        given will override values from configuration files.
 275        The <name> is expected in the same format as listed by
 276        'git config' (subkeys separated by dots).
 277
 278--exec-path[=<path>]::
 279        Path to wherever your core git programs are installed.
 280        This can also be controlled by setting the GIT_EXEC_PATH
 281        environment variable. If no path is given, 'git' will print
 282        the current setting and then exit.
 283
 284--html-path::
 285        Print the path to wherever your git HTML documentation is installed
 286        and exit.
 287
 288-p::
 289--paginate::
 290        Pipe all output into 'less' (or if set, $PAGER) if standard
 291        output is a terminal.  This overrides the `pager.<cmd>`
 292        configuration options (see the "Configuration Mechanism" section
 293        below).
 294
 295--no-pager::
 296        Do not pipe git output into a pager.
 297
 298--git-dir=<path>::
 299        Set the path to the repository. This can also be controlled by
 300        setting the GIT_DIR environment variable. It can be an absolute
 301        path or relative path to current working directory.
 302
 303--work-tree=<path>::
 304        Set the path to the working tree. It can be an absolute path
 305        or a path relative to the current working directory.
 306        This can also be controlled by setting the GIT_WORK_TREE
 307        environment variable and the core.worktree configuration
 308        variable (see core.worktree in linkgit:git-config[1] for a
 309        more detailed discussion).
 310
 311--bare::
 312        Treat the repository as a bare repository.  If GIT_DIR
 313        environment is not set, it is set to the current working
 314        directory.
 315
 316--no-replace-objects::
 317        Do not use replacement refs to replace git objects. See
 318        linkgit:git-replace[1] for more information.
 319
 320
 321FURTHER DOCUMENTATION
 322---------------------
 323
 324See the references above to get started using git.  The following is
 325probably more detail than necessary for a first-time user.
 326
 327The link:user-manual.html#git-concepts[git concepts chapter of the
 328user-manual] and linkgit:gitcore-tutorial[7] both provide
 329introductions to the underlying git architecture.
 330
 331See linkgit:gitworkflows[7] for an overview of recommended workflows.
 332
 333See also the link:howto-index.html[howto] documents for some useful
 334examples.
 335
 336The internals are documented in the
 337link:technical/api-index.html[GIT API documentation].
 338
 339GIT COMMANDS
 340------------
 341
 342We divide git into high level ("porcelain") commands and low level
 343("plumbing") commands.
 344
 345High-level commands (porcelain)
 346-------------------------------
 347
 348We separate the porcelain commands into the main commands and some
 349ancillary user utilities.
 350
 351Main porcelain commands
 352~~~~~~~~~~~~~~~~~~~~~~~
 353
 354include::cmds-mainporcelain.txt[]
 355
 356Ancillary Commands
 357~~~~~~~~~~~~~~~~~~
 358Manipulators:
 359
 360include::cmds-ancillarymanipulators.txt[]
 361
 362Interrogators:
 363
 364include::cmds-ancillaryinterrogators.txt[]
 365
 366
 367Interacting with Others
 368~~~~~~~~~~~~~~~~~~~~~~~
 369
 370These commands are to interact with foreign SCM and with other
 371people via patch over e-mail.
 372
 373include::cmds-foreignscminterface.txt[]
 374
 375
 376Low-level commands (plumbing)
 377-----------------------------
 378
 379Although git includes its
 380own porcelain layer, its low-level commands are sufficient to support
 381development of alternative porcelains.  Developers of such porcelains
 382might start by reading about linkgit:git-update-index[1] and
 383linkgit:git-read-tree[1].
 384
 385The interface (input, output, set of options and the semantics)
 386to these low-level commands are meant to be a lot more stable
 387than Porcelain level commands, because these commands are
 388primarily for scripted use.  The interface to Porcelain commands
 389on the other hand are subject to change in order to improve the
 390end user experience.
 391
 392The following description divides
 393the low-level commands into commands that manipulate objects (in
 394the repository, index, and working tree), commands that interrogate and
 395compare objects, and commands that move objects and references between
 396repositories.
 397
 398
 399Manipulation commands
 400~~~~~~~~~~~~~~~~~~~~~
 401
 402include::cmds-plumbingmanipulators.txt[]
 403
 404
 405Interrogation commands
 406~~~~~~~~~~~~~~~~~~~~~~
 407
 408include::cmds-plumbinginterrogators.txt[]
 409
 410In general, the interrogate commands do not touch the files in
 411the working tree.
 412
 413
 414Synching repositories
 415~~~~~~~~~~~~~~~~~~~~~
 416
 417include::cmds-synchingrepositories.txt[]
 418
 419The following are helper commands used by the above; end users
 420typically do not use them directly.
 421
 422include::cmds-synchelpers.txt[]
 423
 424
 425Internal helper commands
 426~~~~~~~~~~~~~~~~~~~~~~~~
 427
 428These are internal helper commands used by other commands; end
 429users typically do not use them directly.
 430
 431include::cmds-purehelpers.txt[]
 432
 433
 434Configuration Mechanism
 435-----------------------
 436
 437Starting from 0.99.9 (actually mid 0.99.8.GIT), `.git/config` file
 438is used to hold per-repository configuration options.  It is a
 439simple text file modeled after `.ini` format familiar to some
 440people.  Here is an example:
 441
 442------------
 443#
 444# A '#' or ';' character indicates a comment.
 445#
 446
 447; core variables
 448[core]
 449        ; Don't trust file modes
 450        filemode = false
 451
 452; user identity
 453[user]
 454        name = "Junio C Hamano"
 455        email = "junkio@twinsun.com"
 456
 457------------
 458
 459Various commands read from the configuration file and adjust
 460their operation accordingly.  See linkgit:git-config[1] for a
 461list.
 462
 463
 464Identifier Terminology
 465----------------------
 466<object>::
 467        Indicates the object name for any type of object.
 468
 469<blob>::
 470        Indicates a blob object name.
 471
 472<tree>::
 473        Indicates a tree object name.
 474
 475<commit>::
 476        Indicates a commit object name.
 477
 478<tree-ish>::
 479        Indicates a tree, commit or tag object name.  A
 480        command that takes a <tree-ish> argument ultimately wants to
 481        operate on a <tree> object but automatically dereferences
 482        <commit> and <tag> objects that point at a <tree>.
 483
 484<commit-ish>::
 485        Indicates a commit or tag object name.  A
 486        command that takes a <commit-ish> argument ultimately wants to
 487        operate on a <commit> object but automatically dereferences
 488        <tag> objects that point at a <commit>.
 489
 490<type>::
 491        Indicates that an object type is required.
 492        Currently one of: `blob`, `tree`, `commit`, or `tag`.
 493
 494<file>::
 495        Indicates a filename - almost always relative to the
 496        root of the tree structure `GIT_INDEX_FILE` describes.
 497
 498Symbolic Identifiers
 499--------------------
 500Any git command accepting any <object> can also use the following
 501symbolic notation:
 502
 503HEAD::
 504        indicates the head of the current branch (i.e. the
 505        contents of `$GIT_DIR/HEAD`).
 506
 507<tag>::
 508        a valid tag 'name'
 509        (i.e. the contents of `$GIT_DIR/refs/tags/<tag>`).
 510
 511<head>::
 512        a valid head 'name'
 513        (i.e. the contents of `$GIT_DIR/refs/heads/<head>`).
 514
 515For a more complete list of ways to spell object names, see
 516"SPECIFYING REVISIONS" section in linkgit:gitrevisions[7].
 517
 518
 519File/Directory Structure
 520------------------------
 521
 522Please see the linkgit:gitrepository-layout[5] document.
 523
 524Read linkgit:githooks[5] for more details about each hook.
 525
 526Higher level SCMs may provide and manage additional information in the
 527`$GIT_DIR`.
 528
 529
 530Terminology
 531-----------
 532Please see linkgit:gitglossary[7].
 533
 534
 535Environment Variables
 536---------------------
 537Various git commands use the following environment variables:
 538
 539The git Repository
 540~~~~~~~~~~~~~~~~~~
 541These environment variables apply to 'all' core git commands. Nb: it
 542is worth noting that they may be used/overridden by SCMS sitting above
 543git so take care if using Cogito etc.
 544
 545'GIT_INDEX_FILE'::
 546        This environment allows the specification of an alternate
 547        index file. If not specified, the default of `$GIT_DIR/index`
 548        is used.
 549
 550'GIT_OBJECT_DIRECTORY'::
 551        If the object storage directory is specified via this
 552        environment variable then the sha1 directories are created
 553        underneath - otherwise the default `$GIT_DIR/objects`
 554        directory is used.
 555
 556'GIT_ALTERNATE_OBJECT_DIRECTORIES'::
 557        Due to the immutable nature of git objects, old objects can be
 558        archived into shared, read-only directories. This variable
 559        specifies a ":" separated (on Windows ";" separated) list
 560        of git object directories which can be used to search for git
 561        objects. New objects will not be written to these directories.
 562
 563'GIT_DIR'::
 564        If the 'GIT_DIR' environment variable is set then it
 565        specifies a path to use instead of the default `.git`
 566        for the base of the repository.
 567
 568'GIT_WORK_TREE'::
 569        Set the path to the working tree.  The value will not be
 570        used in combination with repositories found automatically in
 571        a .git directory (i.e. $GIT_DIR is not set).
 572        This can also be controlled by the '--work-tree' command line
 573        option and the core.worktree configuration variable.
 574
 575'GIT_CEILING_DIRECTORIES'::
 576        This should be a colon-separated list of absolute paths.
 577        If set, it is a list of directories that git should not chdir
 578        up into while looking for a repository directory.
 579        It will not exclude the current working directory or
 580        a GIT_DIR set on the command line or in the environment.
 581        (Useful for excluding slow-loading network directories.)
 582
 583'GIT_DISCOVERY_ACROSS_FILESYSTEM'::
 584        When run in a directory that does not have ".git" repository
 585        directory, git tries to find such a directory in the parent
 586        directories to find the top of the working tree, but by default it
 587        does not cross filesystem boundaries.  This environment variable
 588        can be set to true to tell git not to stop at filesystem
 589        boundaries.  Like 'GIT_CEILING_DIRECTORIES', this will not affect
 590        an explicit repository directory set via 'GIT_DIR' or on the
 591        command line.
 592
 593git Commits
 594~~~~~~~~~~~
 595'GIT_AUTHOR_NAME'::
 596'GIT_AUTHOR_EMAIL'::
 597'GIT_AUTHOR_DATE'::
 598'GIT_COMMITTER_NAME'::
 599'GIT_COMMITTER_EMAIL'::
 600'GIT_COMMITTER_DATE'::
 601'EMAIL'::
 602        see linkgit:git-commit-tree[1]
 603
 604git Diffs
 605~~~~~~~~~
 606'GIT_DIFF_OPTS'::
 607        Only valid setting is "--unified=??" or "-u??" to set the
 608        number of context lines shown when a unified diff is created.
 609        This takes precedence over any "-U" or "--unified" option
 610        value passed on the git diff command line.
 611
 612'GIT_EXTERNAL_DIFF'::
 613        When the environment variable 'GIT_EXTERNAL_DIFF' is set, the
 614        program named by it is called, instead of the diff invocation
 615        described above.  For a path that is added, removed, or modified,
 616        'GIT_EXTERNAL_DIFF' is called with 7 parameters:
 617
 618        path old-file old-hex old-mode new-file new-hex new-mode
 619+
 620where:
 621
 622        <old|new>-file:: are files GIT_EXTERNAL_DIFF can use to read the
 623                         contents of <old|new>,
 624        <old|new>-hex:: are the 40-hexdigit SHA1 hashes,
 625        <old|new>-mode:: are the octal representation of the file modes.
 626+
 627The file parameters can point at the user's working file
 628(e.g. `new-file` in "git-diff-files"), `/dev/null` (e.g. `old-file`
 629when a new file is added), or a temporary file (e.g. `old-file` in the
 630index).  'GIT_EXTERNAL_DIFF' should not worry about unlinking the
 631temporary file --- it is removed when 'GIT_EXTERNAL_DIFF' exits.
 632+
 633For a path that is unmerged, 'GIT_EXTERNAL_DIFF' is called with 1
 634parameter, <path>.
 635
 636other
 637~~~~~
 638'GIT_MERGE_VERBOSITY'::
 639        A number controlling the amount of output shown by
 640        the recursive merge strategy.  Overrides merge.verbosity.
 641        See linkgit:git-merge[1]
 642
 643'GIT_PAGER'::
 644        This environment variable overrides `$PAGER`. If it is set
 645        to an empty string or to the value "cat", git will not launch
 646        a pager.  See also the `core.pager` option in
 647        linkgit:git-config[1].
 648
 649'GIT_SSH'::
 650        If this environment variable is set then 'git fetch'
 651        and 'git push' will use this command instead
 652        of 'ssh' when they need to connect to a remote system.
 653        The '$GIT_SSH' command will be given exactly two arguments:
 654        the 'username@host' (or just 'host') from the URL and the
 655        shell command to execute on that remote system.
 656+
 657To pass options to the program that you want to list in GIT_SSH
 658you will need to wrap the program and options into a shell script,
 659then set GIT_SSH to refer to the shell script.
 660+
 661Usually it is easier to configure any desired options through your
 662personal `.ssh/config` file.  Please consult your ssh documentation
 663for further details.
 664
 665'GIT_ASKPASS'::
 666        If this environment variable is set, then git commands which need to
 667        acquire passwords or passphrases (e.g. for HTTP or IMAP authentication)
 668        will call this program with a suitable prompt as command line argument
 669        and read the password from its STDOUT. See also the 'core.askpass'
 670        option in linkgit:git-config[1].
 671
 672'GIT_FLUSH'::
 673        If this environment variable is set to "1", then commands such
 674        as 'git blame' (in incremental mode), 'git rev-list', 'git log',
 675        and 'git whatchanged' will force a flush of the output stream
 676        after each commit-oriented record have been flushed.   If this
 677        variable is set to "0", the output of these commands will be done
 678        using completely buffered I/O.   If this environment variable is
 679        not set, git will choose buffered or record-oriented flushing
 680        based on whether stdout appears to be redirected to a file or not.
 681
 682'GIT_TRACE'::
 683        If this variable is set to "1", "2" or "true" (comparison
 684        is case insensitive), git will print `trace:` messages on
 685        stderr telling about alias expansion, built-in command
 686        execution and external command execution.
 687        If this variable is set to an integer value greater than 1
 688        and lower than 10 (strictly) then git will interpret this
 689        value as an open file descriptor and will try to write the
 690        trace messages into this file descriptor.
 691        Alternatively, if this variable is set to an absolute path
 692        (starting with a '/' character), git will interpret this
 693        as a file path and will try to write the trace messages
 694        into it.
 695
 696Discussion[[Discussion]]
 697------------------------
 698
 699More detail on the following is available from the
 700link:user-manual.html#git-concepts[git concepts chapter of the
 701user-manual] and linkgit:gitcore-tutorial[7].
 702
 703A git project normally consists of a working directory with a ".git"
 704subdirectory at the top level.  The .git directory contains, among other
 705things, a compressed object database representing the complete history
 706of the project, an "index" file which links that history to the current
 707contents of the working tree, and named pointers into that history such
 708as tags and branch heads.
 709
 710The object database contains objects of three main types: blobs, which
 711hold file data; trees, which point to blobs and other trees to build up
 712directory hierarchies; and commits, which each reference a single tree
 713and some number of parent commits.
 714
 715The commit, equivalent to what other systems call a "changeset" or
 716"version", represents a step in the project's history, and each parent
 717represents an immediately preceding step.  Commits with more than one
 718parent represent merges of independent lines of development.
 719
 720All objects are named by the SHA1 hash of their contents, normally
 721written as a string of 40 hex digits.  Such names are globally unique.
 722The entire history leading up to a commit can be vouched for by signing
 723just that commit.  A fourth object type, the tag, is provided for this
 724purpose.
 725
 726When first created, objects are stored in individual files, but for
 727efficiency may later be compressed together into "pack files".
 728
 729Named pointers called refs mark interesting points in history.  A ref
 730may contain the SHA1 name of an object or the name of another ref.  Refs
 731with names beginning `ref/head/` contain the SHA1 name of the most
 732recent commit (or "head") of a branch under development.  SHA1 names of
 733tags of interest are stored under `ref/tags/`.  A special ref named
 734`HEAD` contains the name of the currently checked-out branch.
 735
 736The index file is initialized with a list of all paths and, for each
 737path, a blob object and a set of attributes.  The blob object represents
 738the contents of the file as of the head of the current branch.  The
 739attributes (last modified time, size, etc.) are taken from the
 740corresponding file in the working tree.  Subsequent changes to the
 741working tree can be found by comparing these attributes.  The index may
 742be updated with new content, and new commits may be created from the
 743content stored in the index.
 744
 745The index is also capable of storing multiple entries (called "stages")
 746for a given pathname.  These stages are used to hold the various
 747unmerged version of a file when a merge is in progress.
 748
 749Authors
 750-------
 751Git was started by Linus Torvalds, and is currently maintained by Junio
 752C Hamano. Numerous contributions have come from the git mailing list
 753<git@vger.kernel.org>. For a more complete list of contributors, see
 754http://git-scm.com/about. If you have a clone of git.git itself, the
 755output of linkgit:git-shortlog[1] and linkgit:git-blame[1] can show you
 756the authors for specific parts of the project.
 757
 758Reporting Bugs
 759--------------
 760
 761Report bugs to the Git mailing list <git@vger.kernel.org> where the
 762development and maintenance is primarily done.  You do not have to be
 763subscribed to the list to send a message there.
 764
 765SEE ALSO
 766--------
 767linkgit:gittutorial[7], linkgit:gittutorial-2[7],
 768link:everyday.html[Everyday Git], linkgit:gitcvs-migration[7],
 769linkgit:gitglossary[7], linkgit:gitcore-tutorial[7],
 770linkgit:gitcli[7], link:user-manual.html[The Git User's Manual],
 771linkgit:gitworkflows[7]
 772
 773GIT
 774---
 775Part of the linkgit:git[1] suite