Documentation / git.txton commit Merge branch 'nd/fix-sparse-checkout' (c3b9325)
   1git(1)
   2======
   3
   4NAME
   5----
   6git - the stupid content tracker
   7
   8
   9SYNOPSIS
  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
  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:v1.7.2.2/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
 224endif::stalenotes[]
 225
 226OPTIONS
 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+
 237Other options are available to control how the manual page is
 238displayed. See linkgit:git-help[1] for more information,
 239because `git --help ...` is converted internally into `git
 240help ...`.
 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
 296FURTHER DOCUMENTATION
 297---------------------
 298
 299See the references above to get started using git.  The following is
 300probably more detail than necessary for a first-time user.
 301
 302The link:user-manual.html#git-concepts[git concepts chapter of the
 303user-manual] and linkgit:gitcore-tutorial[7] both provide
 304introductions to the underlying git architecture.
 305
 306See linkgit:gitworkflows[7] for an overview of recommended workflows.
 307
 308See also the link:howto-index.html[howto] documents for some useful
 309examples.
 310
 311The internals are documented in the
 312link:technical/api-index.html[GIT API documentation].
 313
 314GIT COMMANDS
 315------------
 316
 317We divide git into high level ("porcelain") commands and low level
 318("plumbing") commands.
 319
 320High-level commands (porcelain)
 321-------------------------------
 322
 323We separate the porcelain commands into the main commands and some
 324ancillary user utilities.
 325
 326Main porcelain commands
 327~~~~~~~~~~~~~~~~~~~~~~~
 328
 329include::cmds-mainporcelain.txt[]
 330
 331Ancillary Commands
 332~~~~~~~~~~~~~~~~~~
 333Manipulators:
 334
 335include::cmds-ancillarymanipulators.txt[]
 336
 337Interrogators:
 338
 339include::cmds-ancillaryinterrogators.txt[]
 340
 341
 342Interacting with Others
 343~~~~~~~~~~~~~~~~~~~~~~~
 344
 345These commands are to interact with foreign SCM and with other
 346people via patch over e-mail.
 347
 348include::cmds-foreignscminterface.txt[]
 349
 350
 351Low-level commands (plumbing)
 352-----------------------------
 353
 354Although git includes its
 355own porcelain layer, its low-level commands are sufficient to support
 356development of alternative porcelains.  Developers of such porcelains
 357might start by reading about linkgit:git-update-index[1] and
 358linkgit:git-read-tree[1].
 359
 360The interface (input, output, set of options and the semantics)
 361to these low-level commands are meant to be a lot more stable
 362than Porcelain level commands, because these commands are
 363primarily for scripted use.  The interface to Porcelain commands
 364on the other hand are subject to change in order to improve the
 365end user experience.
 366
 367The following description divides
 368the low-level commands into commands that manipulate objects (in
 369the repository, index, and working tree), commands that interrogate and
 370compare objects, and commands that move objects and references between
 371repositories.
 372
 373
 374Manipulation commands
 375~~~~~~~~~~~~~~~~~~~~~
 376
 377include::cmds-plumbingmanipulators.txt[]
 378
 379
 380Interrogation commands
 381~~~~~~~~~~~~~~~~~~~~~~
 382
 383include::cmds-plumbinginterrogators.txt[]
 384
 385In general, the interrogate commands do not touch the files in
 386the working tree.
 387
 388
 389Synching repositories
 390~~~~~~~~~~~~~~~~~~~~~
 391
 392include::cmds-synchingrepositories.txt[]
 393
 394The following are helper commands used by the above; end users
 395typically do not use them directly.
 396
 397include::cmds-synchelpers.txt[]
 398
 399
 400Internal helper commands
 401~~~~~~~~~~~~~~~~~~~~~~~~
 402
 403These are internal helper commands used by other commands; end
 404users typically do not use them directly.
 405
 406include::cmds-purehelpers.txt[]
 407
 408
 409Configuration Mechanism
 410-----------------------
 411
 412Starting from 0.99.9 (actually mid 0.99.8.GIT), `.git/config` file
 413is used to hold per-repository configuration options.  It is a
 414simple text file modeled after `.ini` format familiar to some
 415people.  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
 434Various commands read from the configuration file and adjust
 435their operation accordingly.  See linkgit:git-config[1] for a
 436list.
 437
 438
 439Identifier 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
 473Symbolic Identifiers
 474--------------------
 475Any git command accepting any <object> can also use the following
 476symbolic notation:
 477
 478HEAD::
 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
 490For a more complete list of ways to spell object names, see
 491"SPECIFYING REVISIONS" section in linkgit:gitrevisions[1].
 492
 493
 494File/Directory Structure
 495------------------------
 496
 497Please see the linkgit:gitrepository-layout[5] document.
 498
 499Read linkgit:githooks[5] for more details about each hook.
 500
 501Higher level SCMs may provide and manage additional information in the
 502`$GIT_DIR`.
 503
 504
 505Terminology
 506-----------
 507Please see linkgit:gitglossary[7].
 508
 509
 510Environment Variables
 511---------------------
 512Various git commands use the following environment variables:
 513
 514The git Repository
 515~~~~~~~~~~~~~~~~~~
 516These environment variables apply to 'all' core git commands. Nb: it
 517is worth noting that they may be used/overridden by SCMS sitting above
 518git so take care if using Cogito etc.
 519
 520'GIT_INDEX_FILE'::
 521        This environment allows the specification of an alternate
 522        index file. If not specified, the default of `$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
 568git 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
 579git 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+
 595where:
 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+
 603The 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`
 605when a new file is added), or a temporary file (e.g. `old-file` in the
 606index).  'GIT_EXTERNAL_DIFF' should not worry about unlinking the
 607temporary file --- it is removed when 'GIT_EXTERNAL_DIFF' exits.
 608+
 609For a path that is unmerged, 'GIT_EXTERNAL_DIFF' is called with 1
 610parameter, <path>.
 611
 612other
 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+
 633To pass options to the program that you want to list in GIT_SSH
 634you will need to wrap the program and options into a shell script,
 635then set GIT_SSH to refer to the shell script.
 636+
 637Usually it is easier to configure any desired options through your
 638personal `.ssh/config` file.  Please consult your ssh documentation
 639for 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
 665Discussion[[Discussion]]
 666------------------------
 667
 668More detail on the following is available from the
 669link:user-manual.html#git-concepts[git concepts chapter of the
 670user-manual] and linkgit:gitcore-tutorial[7].
 671
 672A git project normally consists of a working directory with a ".git"
 673subdirectory at the top level.  The .git directory contains, among other
 674things, a compressed object database representing the complete history
 675of the project, an "index" file which links that history to the current
 676contents of the working tree, and named pointers into that history such
 677as tags and branch heads.
 678
 679The object database contains objects of three main types: blobs, which
 680hold file data; trees, which point to blobs and other trees to build up
 681directory hierarchies; and commits, which each reference a single tree
 682and some number of parent commits.
 683
 684The commit, equivalent to what other systems call a "changeset" or
 685"version", represents a step in the project's history, and each parent
 686represents an immediately preceding step.  Commits with more than one
 687parent represent merges of independent lines of development.
 688
 689All objects are named by the SHA1 hash of their contents, normally
 690written as a string of 40 hex digits.  Such names are globally unique.
 691The entire history leading up to a commit can be vouched for by signing
 692just that commit.  A fourth object type, the tag, is provided for this
 693purpose.
 694
 695When first created, objects are stored in individual files, but for
 696efficiency may later be compressed together into "pack files".
 697
 698Named pointers called refs mark interesting points in history.  A ref
 699may contain the SHA1 name of an object or the name of another ref.  Refs
 700with names beginning `ref/head/` contain the SHA1 name of the most
 701recent commit (or "head") of a branch under development.  SHA1 names of
 702tags of interest are stored under `ref/tags/`.  A special ref named
 703`HEAD` contains the name of the currently checked-out branch.
 704
 705The index file is initialized with a list of all paths and, for each
 706path, a blob object and a set of attributes.  The blob object represents
 707the contents of the file as of the head of the current branch.  The
 708attributes (last modified time, size, etc.) are taken from the
 709corresponding file in the working tree.  Subsequent changes to the
 710working tree can be found by comparing these attributes.  The index may
 711be updated with new content, and new commits may be created from the
 712content stored in the index.
 713
 714The index is also capable of storing multiple entries (called "stages")
 715for a given pathname.  These stages are used to hold the various
 716unmerged version of a file when a merge is in progress.
 717
 718Authors
 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
 725Documentation
 726--------------
 727The documentation for git suite was started by David Greaves
 728<david@dgreaves.com>, and later enhanced greatly by the
 729contributors on the git-list <git@vger.kernel.org>.
 730
 731Reporting Bugs
 732--------------
 733
 734Report bugs to the Git mailing list <git@vger.kernel.org> where the
 735development and maintenance is primarily done.  You do not have to be
 736subscribed to the list to send a message there.
 737
 738SEE ALSO
 739--------
 740linkgit:gittutorial[7], linkgit:gittutorial-2[7],
 741link:everyday.html[Everyday Git], linkgit:gitcvs-migration[7],
 742linkgit:gitglossary[7], linkgit:gitcore-tutorial[7],
 743linkgit:gitcli[7], link:user-manual.html[The Git User's Manual],
 744linkgit:gitworkflows[7]
 745
 746GIT
 747---
 748Part of the linkgit:git[1] suite