Documentation / git.txton commit Merge branch 'tc/http-urls-ends-with-slash' (a0078de)
   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:v1.7.3.3/git.html[documentation for release 1.7.3.3]
  48
  49* release notes for
  50  link:RelNotes/1.7.3.3.txt[1.7.3.3],
  51  link:RelNotes/1.7.3.2.txt[1.7.3.2],
  52  link:RelNotes/1.7.3.1.txt[1.7.3.1],
  53  link:RelNotes/1.7.3.txt[1.7.3].
  54
  55* link:v1.7.2.4/git.html[documentation for release 1.7.2.4]
  56
  57* release notes for
  58  link:RelNotes/1.7.2.4.txt[1.7.2.4],
  59  link:RelNotes/1.7.2.3.txt[1.7.2.3],
  60  link:RelNotes/1.7.2.2.txt[1.7.2.2],
  61  link:RelNotes/1.7.2.1.txt[1.7.2.1],
  62  link:RelNotes/1.7.2.txt[1.7.2].
  63
  64* link:v1.7.1.3/git.html[documentation for release 1.7.1.3]
  65
  66* release notes for
  67  link:RelNotes/1.7.1.3.txt[1.7.1.3],
  68  link:RelNotes/1.7.1.2.txt[1.7.1.2],
  69  link:RelNotes/1.7.1.1.txt[1.7.1.1],
  70  link:RelNotes/1.7.1.txt[1.7.1].
  71
  72* link:v1.7.0.8/git.html[documentation for release 1.7.0.8]
  73
  74* release notes for
  75  link:RelNotes/1.7.0.8.txt[1.7.0.8],
  76  link:RelNotes/1.7.0.7.txt[1.7.0.7],
  77  link:RelNotes/1.7.0.6.txt[1.7.0.6],
  78  link:RelNotes/1.7.0.5.txt[1.7.0.5],
  79  link:RelNotes/1.7.0.4.txt[1.7.0.4],
  80  link:RelNotes/1.7.0.3.txt[1.7.0.3],
  81  link:RelNotes/1.7.0.2.txt[1.7.0.2],
  82  link:RelNotes/1.7.0.1.txt[1.7.0.1],
  83  link:RelNotes/1.7.0.txt[1.7.0].
  84
  85* link:v1.6.6.2/git.html[documentation for release 1.6.6.2]
  86
  87* release notes for
  88  link:RelNotes/1.6.6.2.txt[1.6.6.2],
  89  link:RelNotes/1.6.6.1.txt[1.6.6.1],
  90  link:RelNotes/1.6.6.txt[1.6.6].
  91
  92* link:v1.6.5.8/git.html[documentation for release 1.6.5.8]
  93
  94* release notes for
  95  link:RelNotes/1.6.5.8.txt[1.6.5.8],
  96  link:RelNotes/1.6.5.7.txt[1.6.5.7],
  97  link:RelNotes/1.6.5.6.txt[1.6.5.6],
  98  link:RelNotes/1.6.5.5.txt[1.6.5.5],
  99  link:RelNotes/1.6.5.4.txt[1.6.5.4],
 100  link:RelNotes/1.6.5.3.txt[1.6.5.3],
 101  link:RelNotes/1.6.5.2.txt[1.6.5.2],
 102  link:RelNotes/1.6.5.1.txt[1.6.5.1],
 103  link:RelNotes/1.6.5.txt[1.6.5].
 104
 105* link:v1.6.4.4/git.html[documentation for release 1.6.4.4]
 106
 107* release notes for
 108  link:RelNotes/1.6.4.4.txt[1.6.4.4],
 109  link:RelNotes/1.6.4.3.txt[1.6.4.3],
 110  link:RelNotes/1.6.4.2.txt[1.6.4.2],
 111  link:RelNotes/1.6.4.1.txt[1.6.4.1],
 112  link:RelNotes/1.6.4.txt[1.6.4].
 113
 114* link:v1.6.3.4/git.html[documentation for release 1.6.3.4]
 115
 116* release notes for
 117  link:RelNotes/1.6.3.4.txt[1.6.3.4],
 118  link:RelNotes/1.6.3.3.txt[1.6.3.3],
 119  link:RelNotes/1.6.3.2.txt[1.6.3.2],
 120  link:RelNotes/1.6.3.1.txt[1.6.3.1],
 121  link:RelNotes/1.6.3.txt[1.6.3].
 122
 123* release notes for
 124  link:RelNotes/1.6.2.5.txt[1.6.2.5],
 125  link:RelNotes/1.6.2.4.txt[1.6.2.4],
 126  link:RelNotes/1.6.2.3.txt[1.6.2.3],
 127  link:RelNotes/1.6.2.2.txt[1.6.2.2],
 128  link:RelNotes/1.6.2.1.txt[1.6.2.1],
 129  link:RelNotes/1.6.2.txt[1.6.2].
 130
 131* link:v1.6.1.3/git.html[documentation for release 1.6.1.3]
 132
 133* release notes for
 134  link:RelNotes/1.6.1.3.txt[1.6.1.3],
 135  link:RelNotes/1.6.1.2.txt[1.6.1.2],
 136  link:RelNotes/1.6.1.1.txt[1.6.1.1],
 137  link:RelNotes/1.6.1.txt[1.6.1].
 138
 139* link:v1.6.0.6/git.html[documentation for release 1.6.0.6]
 140
 141* release notes for
 142  link:RelNotes/1.6.0.6.txt[1.6.0.6],
 143  link:RelNotes/1.6.0.5.txt[1.6.0.5],
 144  link:RelNotes/1.6.0.4.txt[1.6.0.4],
 145  link:RelNotes/1.6.0.3.txt[1.6.0.3],
 146  link:RelNotes/1.6.0.2.txt[1.6.0.2],
 147  link:RelNotes/1.6.0.1.txt[1.6.0.1],
 148  link:RelNotes/1.6.0.txt[1.6.0].
 149
 150* link:v1.5.6.6/git.html[documentation for release 1.5.6.6]
 151
 152* release notes for
 153  link:RelNotes/1.5.6.6.txt[1.5.6.6],
 154  link:RelNotes/1.5.6.5.txt[1.5.6.5],
 155  link:RelNotes/1.5.6.4.txt[1.5.6.4],
 156  link:RelNotes/1.5.6.3.txt[1.5.6.3],
 157  link:RelNotes/1.5.6.2.txt[1.5.6.2],
 158  link:RelNotes/1.5.6.1.txt[1.5.6.1],
 159  link:RelNotes/1.5.6.txt[1.5.6].
 160
 161* link:v1.5.5.6/git.html[documentation for release 1.5.5.6]
 162
 163* release notes for
 164  link:RelNotes/1.5.5.6.txt[1.5.5.6],
 165  link:RelNotes/1.5.5.5.txt[1.5.5.5],
 166  link:RelNotes/1.5.5.4.txt[1.5.5.4],
 167  link:RelNotes/1.5.5.3.txt[1.5.5.3],
 168  link:RelNotes/1.5.5.2.txt[1.5.5.2],
 169  link:RelNotes/1.5.5.1.txt[1.5.5.1],
 170  link:RelNotes/1.5.5.txt[1.5.5].
 171
 172* link:v1.5.4.7/git.html[documentation for release 1.5.4.7]
 173
 174* release notes for
 175  link:RelNotes/1.5.4.7.txt[1.5.4.7],
 176  link:RelNotes/1.5.4.6.txt[1.5.4.6],
 177  link:RelNotes/1.5.4.5.txt[1.5.4.5],
 178  link:RelNotes/1.5.4.4.txt[1.5.4.4],
 179  link:RelNotes/1.5.4.3.txt[1.5.4.3],
 180  link:RelNotes/1.5.4.2.txt[1.5.4.2],
 181  link:RelNotes/1.5.4.1.txt[1.5.4.1],
 182  link:RelNotes/1.5.4.txt[1.5.4].
 183
 184* link:v1.5.3.8/git.html[documentation for release 1.5.3.8]
 185
 186* release notes for
 187  link:RelNotes/1.5.3.8.txt[1.5.3.8],
 188  link:RelNotes/1.5.3.7.txt[1.5.3.7],
 189  link:RelNotes/1.5.3.6.txt[1.5.3.6],
 190  link:RelNotes/1.5.3.5.txt[1.5.3.5],
 191  link:RelNotes/1.5.3.4.txt[1.5.3.4],
 192  link:RelNotes/1.5.3.3.txt[1.5.3.3],
 193  link:RelNotes/1.5.3.2.txt[1.5.3.2],
 194  link:RelNotes/1.5.3.1.txt[1.5.3.1],
 195  link:RelNotes/1.5.3.txt[1.5.3].
 196
 197* link:v1.5.2.5/git.html[documentation for release 1.5.2.5]
 198
 199* release notes for
 200  link:RelNotes/1.5.2.5.txt[1.5.2.5],
 201  link:RelNotes/1.5.2.4.txt[1.5.2.4],
 202  link:RelNotes/1.5.2.3.txt[1.5.2.3],
 203  link:RelNotes/1.5.2.2.txt[1.5.2.2],
 204  link:RelNotes/1.5.2.1.txt[1.5.2.1],
 205  link:RelNotes/1.5.2.txt[1.5.2].
 206
 207* link:v1.5.1.6/git.html[documentation for release 1.5.1.6]
 208
 209* release notes for
 210  link:RelNotes/1.5.1.6.txt[1.5.1.6],
 211  link:RelNotes/1.5.1.5.txt[1.5.1.5],
 212  link:RelNotes/1.5.1.4.txt[1.5.1.4],
 213  link:RelNotes/1.5.1.3.txt[1.5.1.3],
 214  link:RelNotes/1.5.1.2.txt[1.5.1.2],
 215  link:RelNotes/1.5.1.1.txt[1.5.1.1],
 216  link:RelNotes/1.5.1.txt[1.5.1].
 217
 218* link:v1.5.0.7/git.html[documentation for release 1.5.0.7]
 219
 220* release notes for
 221  link:RelNotes/1.5.0.7.txt[1.5.0.7],
 222  link:RelNotes/1.5.0.6.txt[1.5.0.6],
 223  link:RelNotes/1.5.0.5.txt[1.5.0.5],
 224  link:RelNotes/1.5.0.3.txt[1.5.0.3],
 225  link:RelNotes/1.5.0.2.txt[1.5.0.2],
 226  link:RelNotes/1.5.0.1.txt[1.5.0.1],
 227  link:RelNotes/1.5.0.txt[1.5.0].
 228
 229* documentation for release link:v1.4.4.4/git.html[1.4.4.4],
 230  link:v1.3.3/git.html[1.3.3],
 231  link:v1.2.6/git.html[1.2.6],
 232  link:v1.0.13/git.html[1.0.13].
 233
 234============
 235
 236endif::stalenotes[]
 237
 238OPTIONS
 239-------
 240--version::
 241        Prints the git suite version that the 'git' program came from.
 242
 243--help::
 244        Prints the synopsis and a list of the most commonly used
 245        commands. If the option '--all' or '-a' is given then all
 246        available commands are printed. If a git command is named this
 247        option will bring up the manual page for that command.
 248+
 249Other options are available to control how the manual page is
 250displayed. See linkgit:git-help[1] for more information,
 251because `git --help ...` is converted internally into `git
 252help ...`.
 253
 254-c <name>=<value>::
 255        Pass a configuration parameter to the command. The value
 256        given will override values from configuration files.
 257        The <name> is expected in the same format as listed by
 258        'git config' (subkeys separated by dots).
 259
 260--exec-path[=<path>]::
 261        Path to wherever your core git programs are installed.
 262        This can also be controlled by setting the GIT_EXEC_PATH
 263        environment variable. If no path is given, 'git' will print
 264        the current setting and then exit.
 265
 266--html-path::
 267        Print the path to wherever your git HTML documentation is installed
 268        and exit.
 269
 270-p::
 271--paginate::
 272        Pipe all output into 'less' (or if set, $PAGER) if standard
 273        output is a terminal.  This overrides the `pager.<cmd>`
 274        configuration options (see the "Configuration Mechanism" section
 275        below).
 276
 277--no-pager::
 278        Do not pipe git output into a pager.
 279
 280--git-dir=<path>::
 281        Set the path to the repository. This can also be controlled by
 282        setting the GIT_DIR environment variable. It can be an absolute
 283        path or relative path to current working directory.
 284
 285--work-tree=<path>::
 286        Set the path to the working tree.  The value will not be
 287        used in combination with repositories found automatically in
 288        a .git directory (i.e. $GIT_DIR is not set).
 289        This can also be controlled by setting the GIT_WORK_TREE
 290        environment variable and the core.worktree configuration
 291        variable. It can be an absolute path or relative path to
 292        the directory specified by --git-dir or GIT_DIR.
 293        Note: If --git-dir or GIT_DIR are specified but none of
 294        --work-tree, GIT_WORK_TREE and core.worktree is specified,
 295        the current working directory is regarded as the top directory
 296        of your working tree.
 297
 298--bare::
 299        Treat the repository as a bare repository.  If GIT_DIR
 300        environment is not set, it is set to the current working
 301        directory.
 302
 303--no-replace-objects::
 304        Do not use replacement refs to replace git objects. See
 305        linkgit:git-replace[1] for more information.
 306
 307
 308FURTHER DOCUMENTATION
 309---------------------
 310
 311See the references above to get started using git.  The following is
 312probably more detail than necessary for a first-time user.
 313
 314The link:user-manual.html#git-concepts[git concepts chapter of the
 315user-manual] and linkgit:gitcore-tutorial[7] both provide
 316introductions to the underlying git architecture.
 317
 318See linkgit:gitworkflows[7] for an overview of recommended workflows.
 319
 320See also the link:howto-index.html[howto] documents for some useful
 321examples.
 322
 323The internals are documented in the
 324link:technical/api-index.html[GIT API documentation].
 325
 326GIT COMMANDS
 327------------
 328
 329We divide git into high level ("porcelain") commands and low level
 330("plumbing") commands.
 331
 332High-level commands (porcelain)
 333-------------------------------
 334
 335We separate the porcelain commands into the main commands and some
 336ancillary user utilities.
 337
 338Main porcelain commands
 339~~~~~~~~~~~~~~~~~~~~~~~
 340
 341include::cmds-mainporcelain.txt[]
 342
 343Ancillary Commands
 344~~~~~~~~~~~~~~~~~~
 345Manipulators:
 346
 347include::cmds-ancillarymanipulators.txt[]
 348
 349Interrogators:
 350
 351include::cmds-ancillaryinterrogators.txt[]
 352
 353
 354Interacting with Others
 355~~~~~~~~~~~~~~~~~~~~~~~
 356
 357These commands are to interact with foreign SCM and with other
 358people via patch over e-mail.
 359
 360include::cmds-foreignscminterface.txt[]
 361
 362
 363Low-level commands (plumbing)
 364-----------------------------
 365
 366Although git includes its
 367own porcelain layer, its low-level commands are sufficient to support
 368development of alternative porcelains.  Developers of such porcelains
 369might start by reading about linkgit:git-update-index[1] and
 370linkgit:git-read-tree[1].
 371
 372The interface (input, output, set of options and the semantics)
 373to these low-level commands are meant to be a lot more stable
 374than Porcelain level commands, because these commands are
 375primarily for scripted use.  The interface to Porcelain commands
 376on the other hand are subject to change in order to improve the
 377end user experience.
 378
 379The following description divides
 380the low-level commands into commands that manipulate objects (in
 381the repository, index, and working tree), commands that interrogate and
 382compare objects, and commands that move objects and references between
 383repositories.
 384
 385
 386Manipulation commands
 387~~~~~~~~~~~~~~~~~~~~~
 388
 389include::cmds-plumbingmanipulators.txt[]
 390
 391
 392Interrogation commands
 393~~~~~~~~~~~~~~~~~~~~~~
 394
 395include::cmds-plumbinginterrogators.txt[]
 396
 397In general, the interrogate commands do not touch the files in
 398the working tree.
 399
 400
 401Synching repositories
 402~~~~~~~~~~~~~~~~~~~~~
 403
 404include::cmds-synchingrepositories.txt[]
 405
 406The following are helper commands used by the above; end users
 407typically do not use them directly.
 408
 409include::cmds-synchelpers.txt[]
 410
 411
 412Internal helper commands
 413~~~~~~~~~~~~~~~~~~~~~~~~
 414
 415These are internal helper commands used by other commands; end
 416users typically do not use them directly.
 417
 418include::cmds-purehelpers.txt[]
 419
 420
 421Configuration Mechanism
 422-----------------------
 423
 424Starting from 0.99.9 (actually mid 0.99.8.GIT), `.git/config` file
 425is used to hold per-repository configuration options.  It is a
 426simple text file modeled after `.ini` format familiar to some
 427people.  Here is an example:
 428
 429------------
 430#
 431# A '#' or ';' character indicates a comment.
 432#
 433
 434; core variables
 435[core]
 436        ; Don't trust file modes
 437        filemode = false
 438
 439; user identity
 440[user]
 441        name = "Junio C Hamano"
 442        email = "junkio@twinsun.com"
 443
 444------------
 445
 446Various commands read from the configuration file and adjust
 447their operation accordingly.  See linkgit:git-config[1] for a
 448list.
 449
 450
 451Identifier Terminology
 452----------------------
 453<object>::
 454        Indicates the object name for any type of object.
 455
 456<blob>::
 457        Indicates a blob object name.
 458
 459<tree>::
 460        Indicates a tree object name.
 461
 462<commit>::
 463        Indicates a commit object name.
 464
 465<tree-ish>::
 466        Indicates a tree, commit or tag object name.  A
 467        command that takes a <tree-ish> argument ultimately wants to
 468        operate on a <tree> object but automatically dereferences
 469        <commit> and <tag> objects that point at a <tree>.
 470
 471<commit-ish>::
 472        Indicates a commit or tag object name.  A
 473        command that takes a <commit-ish> argument ultimately wants to
 474        operate on a <commit> object but automatically dereferences
 475        <tag> objects that point at a <commit>.
 476
 477<type>::
 478        Indicates that an object type is required.
 479        Currently one of: `blob`, `tree`, `commit`, or `tag`.
 480
 481<file>::
 482        Indicates a filename - almost always relative to the
 483        root of the tree structure `GIT_INDEX_FILE` describes.
 484
 485Symbolic Identifiers
 486--------------------
 487Any git command accepting any <object> can also use the following
 488symbolic notation:
 489
 490HEAD::
 491        indicates the head of the current branch (i.e. the
 492        contents of `$GIT_DIR/HEAD`).
 493
 494<tag>::
 495        a valid tag 'name'
 496        (i.e. the contents of `$GIT_DIR/refs/tags/<tag>`).
 497
 498<head>::
 499        a valid head 'name'
 500        (i.e. the contents of `$GIT_DIR/refs/heads/<head>`).
 501
 502For a more complete list of ways to spell object names, see
 503"SPECIFYING REVISIONS" section in linkgit:gitrevisions[7].
 504
 505
 506File/Directory Structure
 507------------------------
 508
 509Please see the linkgit:gitrepository-layout[5] document.
 510
 511Read linkgit:githooks[5] for more details about each hook.
 512
 513Higher level SCMs may provide and manage additional information in the
 514`$GIT_DIR`.
 515
 516
 517Terminology
 518-----------
 519Please see linkgit:gitglossary[7].
 520
 521
 522Environment Variables
 523---------------------
 524Various git commands use the following environment variables:
 525
 526The git Repository
 527~~~~~~~~~~~~~~~~~~
 528These environment variables apply to 'all' core git commands. Nb: it
 529is worth noting that they may be used/overridden by SCMS sitting above
 530git so take care if using Cogito etc.
 531
 532'GIT_INDEX_FILE'::
 533        This environment allows the specification of an alternate
 534        index file. If not specified, the default of `$GIT_DIR/index`
 535        is used.
 536
 537'GIT_OBJECT_DIRECTORY'::
 538        If the object storage directory is specified via this
 539        environment variable then the sha1 directories are created
 540        underneath - otherwise the default `$GIT_DIR/objects`
 541        directory is used.
 542
 543'GIT_ALTERNATE_OBJECT_DIRECTORIES'::
 544        Due to the immutable nature of git objects, old objects can be
 545        archived into shared, read-only directories. This variable
 546        specifies a ":" separated (on Windows ";" separated) list
 547        of git object directories which can be used to search for git
 548        objects. New objects will not be written to these directories.
 549
 550'GIT_DIR'::
 551        If the 'GIT_DIR' environment variable is set then it
 552        specifies a path to use instead of the default `.git`
 553        for the base of the repository.
 554
 555'GIT_WORK_TREE'::
 556        Set the path to the working tree.  The value will not be
 557        used in combination with repositories found automatically in
 558        a .git directory (i.e. $GIT_DIR is not set).
 559        This can also be controlled by the '--work-tree' command line
 560        option and the core.worktree configuration variable.
 561
 562'GIT_CEILING_DIRECTORIES'::
 563        This should be a colon-separated list of absolute paths.
 564        If set, it is a list of directories that git should not chdir
 565        up into while looking for a repository directory.
 566        It will not exclude the current working directory or
 567        a GIT_DIR set on the command line or in the environment.
 568        (Useful for excluding slow-loading network directories.)
 569
 570'GIT_DISCOVERY_ACROSS_FILESYSTEM'::
 571        When run in a directory that does not have ".git" repository
 572        directory, git tries to find such a directory in the parent
 573        directories to find the top of the working tree, but by default it
 574        does not cross filesystem boundaries.  This environment variable
 575        can be set to true to tell git not to stop at filesystem
 576        boundaries.  Like 'GIT_CEILING_DIRECTORIES', this will not affect
 577        an explicit repository directory set via 'GIT_DIR' or on the
 578        command line.
 579
 580git Commits
 581~~~~~~~~~~~
 582'GIT_AUTHOR_NAME'::
 583'GIT_AUTHOR_EMAIL'::
 584'GIT_AUTHOR_DATE'::
 585'GIT_COMMITTER_NAME'::
 586'GIT_COMMITTER_EMAIL'::
 587'GIT_COMMITTER_DATE'::
 588'EMAIL'::
 589        see linkgit:git-commit-tree[1]
 590
 591git Diffs
 592~~~~~~~~~
 593'GIT_DIFF_OPTS'::
 594        Only valid setting is "--unified=??" or "-u??" to set the
 595        number of context lines shown when a unified diff is created.
 596        This takes precedence over any "-U" or "--unified" option
 597        value passed on the git diff command line.
 598
 599'GIT_EXTERNAL_DIFF'::
 600        When the environment variable 'GIT_EXTERNAL_DIFF' is set, the
 601        program named by it is called, instead of the diff invocation
 602        described above.  For a path that is added, removed, or modified,
 603        'GIT_EXTERNAL_DIFF' is called with 7 parameters:
 604
 605        path old-file old-hex old-mode new-file new-hex new-mode
 606+
 607where:
 608
 609        <old|new>-file:: are files GIT_EXTERNAL_DIFF can use to read the
 610                         contents of <old|new>,
 611        <old|new>-hex:: are the 40-hexdigit SHA1 hashes,
 612        <old|new>-mode:: are the octal representation of the file modes.
 613
 614+
 615The file parameters can point at the user's working file
 616(e.g. `new-file` in "git-diff-files"), `/dev/null` (e.g. `old-file`
 617when a new file is added), or a temporary file (e.g. `old-file` in the
 618index).  'GIT_EXTERNAL_DIFF' should not worry about unlinking the
 619temporary file --- it is removed when 'GIT_EXTERNAL_DIFF' exits.
 620+
 621For a path that is unmerged, 'GIT_EXTERNAL_DIFF' is called with 1
 622parameter, <path>.
 623
 624other
 625~~~~~
 626'GIT_MERGE_VERBOSITY'::
 627        A number controlling the amount of output shown by
 628        the recursive merge strategy.  Overrides merge.verbosity.
 629        See linkgit:git-merge[1]
 630
 631'GIT_PAGER'::
 632        This environment variable overrides `$PAGER`. If it is set
 633        to an empty string or to the value "cat", git will not launch
 634        a pager.  See also the `core.pager` option in
 635        linkgit:git-config[1].
 636
 637'GIT_SSH'::
 638        If this environment variable is set then 'git fetch'
 639        and 'git push' will use this command instead
 640        of 'ssh' when they need to connect to a remote system.
 641        The '$GIT_SSH' command will be given exactly two arguments:
 642        the 'username@host' (or just 'host') from the URL and the
 643        shell command to execute on that remote system.
 644+
 645To pass options to the program that you want to list in GIT_SSH
 646you will need to wrap the program and options into a shell script,
 647then set GIT_SSH to refer to the shell script.
 648+
 649Usually it is easier to configure any desired options through your
 650personal `.ssh/config` file.  Please consult your ssh documentation
 651for further details.
 652
 653'GIT_ASKPASS'::
 654        If this environment variable is set, then git commands which need to
 655        acquire passwords or passphrases (e.g. for HTTP or IMAP authentication)
 656        will call this program with a suitable prompt as command line argument
 657        and read the password from its STDOUT. See also the 'core.askpass'
 658        option in linkgit:git-config[1].
 659
 660'GIT_FLUSH'::
 661        If this environment variable is set to "1", then commands such
 662        as 'git blame' (in incremental mode), 'git rev-list', 'git log',
 663        and 'git whatchanged' will force a flush of the output stream
 664        after each commit-oriented record have been flushed.   If this
 665        variable is set to "0", the output of these commands will be done
 666        using completely buffered I/O.   If this environment variable is
 667        not set, git will choose buffered or record-oriented flushing
 668        based on whether stdout appears to be redirected to a file or not.
 669
 670'GIT_TRACE'::
 671        If this variable is set to "1", "2" or "true" (comparison
 672        is case insensitive), git will print `trace:` messages on
 673        stderr telling about alias expansion, built-in command
 674        execution and external command execution.
 675        If this variable is set to an integer value greater than 1
 676        and lower than 10 (strictly) then git will interpret this
 677        value as an open file descriptor and will try to write the
 678        trace messages into this file descriptor.
 679        Alternatively, if this variable is set to an absolute path
 680        (starting with a '/' character), git will interpret this
 681        as a file path and will try to write the trace messages
 682        into it.
 683
 684Discussion[[Discussion]]
 685------------------------
 686
 687More detail on the following is available from the
 688link:user-manual.html#git-concepts[git concepts chapter of the
 689user-manual] and linkgit:gitcore-tutorial[7].
 690
 691A git project normally consists of a working directory with a ".git"
 692subdirectory at the top level.  The .git directory contains, among other
 693things, a compressed object database representing the complete history
 694of the project, an "index" file which links that history to the current
 695contents of the working tree, and named pointers into that history such
 696as tags and branch heads.
 697
 698The object database contains objects of three main types: blobs, which
 699hold file data; trees, which point to blobs and other trees to build up
 700directory hierarchies; and commits, which each reference a single tree
 701and some number of parent commits.
 702
 703The commit, equivalent to what other systems call a "changeset" or
 704"version", represents a step in the project's history, and each parent
 705represents an immediately preceding step.  Commits with more than one
 706parent represent merges of independent lines of development.
 707
 708All objects are named by the SHA1 hash of their contents, normally
 709written as a string of 40 hex digits.  Such names are globally unique.
 710The entire history leading up to a commit can be vouched for by signing
 711just that commit.  A fourth object type, the tag, is provided for this
 712purpose.
 713
 714When first created, objects are stored in individual files, but for
 715efficiency may later be compressed together into "pack files".
 716
 717Named pointers called refs mark interesting points in history.  A ref
 718may contain the SHA1 name of an object or the name of another ref.  Refs
 719with names beginning `ref/head/` contain the SHA1 name of the most
 720recent commit (or "head") of a branch under development.  SHA1 names of
 721tags of interest are stored under `ref/tags/`.  A special ref named
 722`HEAD` contains the name of the currently checked-out branch.
 723
 724The index file is initialized with a list of all paths and, for each
 725path, a blob object and a set of attributes.  The blob object represents
 726the contents of the file as of the head of the current branch.  The
 727attributes (last modified time, size, etc.) are taken from the
 728corresponding file in the working tree.  Subsequent changes to the
 729working tree can be found by comparing these attributes.  The index may
 730be updated with new content, and new commits may be created from the
 731content stored in the index.
 732
 733The index is also capable of storing multiple entries (called "stages")
 734for a given pathname.  These stages are used to hold the various
 735unmerged version of a file when a merge is in progress.
 736
 737Authors
 738-------
 739* git's founding father is Linus Torvalds <torvalds@osdl.org>.
 740* The current git nurse is Junio C Hamano <gitster@pobox.com>.
 741* The git potty was written by Andreas Ericsson <ae@op5.se>.
 742* General upbringing is handled by the git-list <git@vger.kernel.org>.
 743
 744Documentation
 745--------------
 746The documentation for git suite was started by David Greaves
 747<david@dgreaves.com>, and later enhanced greatly by the
 748contributors on the git-list <git@vger.kernel.org>.
 749
 750Reporting Bugs
 751--------------
 752
 753Report bugs to the Git mailing list <git@vger.kernel.org> where the
 754development and maintenance is primarily done.  You do not have to be
 755subscribed to the list to send a message there.
 756
 757SEE ALSO
 758--------
 759linkgit:gittutorial[7], linkgit:gittutorial-2[7],
 760link:everyday.html[Everyday Git], linkgit:gitcvs-migration[7],
 761linkgit:gitglossary[7], linkgit:gitcore-tutorial[7],
 762linkgit:gitcli[7], link:user-manual.html[The Git User's Manual],
 763linkgit:gitworkflows[7]
 764
 765GIT
 766---
 767Part of the linkgit:git[1] suite