Documentation / git.txton commit Sync with 1.7.1.2 (33a0292)
   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/git.html[documentation for release 1.7.2]
  48
  49* release notes for
  50  link:RelNotes-1.7.2.txt[1.7.2].
  51
  52* link:v1.7.1.2/git.html[documentation for release 1.7.1.2]
  53
  54* release notes for
  55  link:RelNotes-1.7.1.2.txt[1.7.1.2],
  56  link:RelNotes-1.7.1.1.txt[1.7.1.1],
  57  link:RelNotes-1.7.1.txt[1.7.1].
  58
  59* link:v1.7.0.7/git.html[documentation for release 1.7.0.7]
  60
  61* release notes for
  62  link:RelNotes-1.7.0.7.txt[1.7.0.7],
  63  link:RelNotes-1.7.0.6.txt[1.7.0.6],
  64  link:RelNotes-1.7.0.5.txt[1.7.0.5],
  65  link:RelNotes-1.7.0.4.txt[1.7.0.4],
  66  link:RelNotes-1.7.0.3.txt[1.7.0.3],
  67  link:RelNotes-1.7.0.2.txt[1.7.0.2],
  68  link:RelNotes-1.7.0.1.txt[1.7.0.1],
  69  link:RelNotes-1.7.0.txt[1.7.0].
  70
  71* link:v1.6.6.2/git.html[documentation for release 1.6.6.2]
  72
  73* release notes for
  74  link:RelNotes-1.6.6.2.txt[1.6.6.2],
  75  link:RelNotes-1.6.6.1.txt[1.6.6.1],
  76  link:RelNotes-1.6.6.txt[1.6.6].
  77
  78* link:v1.6.5.8/git.html[documentation for release 1.6.5.8]
  79
  80* release notes for
  81  link:RelNotes-1.6.5.8.txt[1.6.5.8],
  82  link:RelNotes-1.6.5.7.txt[1.6.5.7],
  83  link:RelNotes-1.6.5.6.txt[1.6.5.6],
  84  link:RelNotes-1.6.5.5.txt[1.6.5.5],
  85  link:RelNotes-1.6.5.4.txt[1.6.5.4],
  86  link:RelNotes-1.6.5.3.txt[1.6.5.3],
  87  link:RelNotes-1.6.5.2.txt[1.6.5.2],
  88  link:RelNotes-1.6.5.1.txt[1.6.5.1],
  89  link:RelNotes-1.6.5.txt[1.6.5].
  90
  91* link:v1.6.4.4/git.html[documentation for release 1.6.4.4]
  92
  93* release notes for
  94  link:RelNotes-1.6.4.4.txt[1.6.4.4],
  95  link:RelNotes-1.6.4.3.txt[1.6.4.3],
  96  link:RelNotes-1.6.4.2.txt[1.6.4.2],
  97  link:RelNotes-1.6.4.1.txt[1.6.4.1],
  98  link:RelNotes-1.6.4.txt[1.6.4].
  99
 100* link:v1.6.3.4/git.html[documentation for release 1.6.3.4]
 101
 102* release notes for
 103  link:RelNotes-1.6.3.4.txt[1.6.3.4],
 104  link:RelNotes-1.6.3.3.txt[1.6.3.3],
 105  link:RelNotes-1.6.3.2.txt[1.6.3.2],
 106  link:RelNotes-1.6.3.1.txt[1.6.3.1],
 107  link:RelNotes-1.6.3.txt[1.6.3].
 108
 109* release notes for
 110  link:RelNotes-1.6.2.5.txt[1.6.2.5],
 111  link:RelNotes-1.6.2.4.txt[1.6.2.4],
 112  link:RelNotes-1.6.2.3.txt[1.6.2.3],
 113  link:RelNotes-1.6.2.2.txt[1.6.2.2],
 114  link:RelNotes-1.6.2.1.txt[1.6.2.1],
 115  link:RelNotes-1.6.2.txt[1.6.2].
 116
 117* link:v1.6.1.3/git.html[documentation for release 1.6.1.3]
 118
 119* release notes for
 120  link:RelNotes-1.6.1.3.txt[1.6.1.3],
 121  link:RelNotes-1.6.1.2.txt[1.6.1.2],
 122  link:RelNotes-1.6.1.1.txt[1.6.1.1],
 123  link:RelNotes-1.6.1.txt[1.6.1].
 124
 125* link:v1.6.0.6/git.html[documentation for release 1.6.0.6]
 126
 127* release notes for
 128  link:RelNotes-1.6.0.6.txt[1.6.0.6],
 129  link:RelNotes-1.6.0.5.txt[1.6.0.5],
 130  link:RelNotes-1.6.0.4.txt[1.6.0.4],
 131  link:RelNotes-1.6.0.3.txt[1.6.0.3],
 132  link:RelNotes-1.6.0.2.txt[1.6.0.2],
 133  link:RelNotes-1.6.0.1.txt[1.6.0.1],
 134  link:RelNotes-1.6.0.txt[1.6.0].
 135
 136* link:v1.5.6.6/git.html[documentation for release 1.5.6.6]
 137
 138* release notes for
 139  link:RelNotes-1.5.6.6.txt[1.5.6.6],
 140  link:RelNotes-1.5.6.5.txt[1.5.6.5],
 141  link:RelNotes-1.5.6.4.txt[1.5.6.4],
 142  link:RelNotes-1.5.6.3.txt[1.5.6.3],
 143  link:RelNotes-1.5.6.2.txt[1.5.6.2],
 144  link:RelNotes-1.5.6.1.txt[1.5.6.1],
 145  link:RelNotes-1.5.6.txt[1.5.6].
 146
 147* link:v1.5.5.6/git.html[documentation for release 1.5.5.6]
 148
 149* release notes for
 150  link:RelNotes-1.5.5.6.txt[1.5.5.6],
 151  link:RelNotes-1.5.5.5.txt[1.5.5.5],
 152  link:RelNotes-1.5.5.4.txt[1.5.5.4],
 153  link:RelNotes-1.5.5.3.txt[1.5.5.3],
 154  link:RelNotes-1.5.5.2.txt[1.5.5.2],
 155  link:RelNotes-1.5.5.1.txt[1.5.5.1],
 156  link:RelNotes-1.5.5.txt[1.5.5].
 157
 158* link:v1.5.4.7/git.html[documentation for release 1.5.4.7]
 159
 160* release notes for
 161  link:RelNotes-1.5.4.7.txt[1.5.4.7],
 162  link:RelNotes-1.5.4.6.txt[1.5.4.6],
 163  link:RelNotes-1.5.4.5.txt[1.5.4.5],
 164  link:RelNotes-1.5.4.4.txt[1.5.4.4],
 165  link:RelNotes-1.5.4.3.txt[1.5.4.3],
 166  link:RelNotes-1.5.4.2.txt[1.5.4.2],
 167  link:RelNotes-1.5.4.1.txt[1.5.4.1],
 168  link:RelNotes-1.5.4.txt[1.5.4].
 169
 170* link:v1.5.3.8/git.html[documentation for release 1.5.3.8]
 171
 172* release notes for
 173  link:RelNotes-1.5.3.8.txt[1.5.3.8],
 174  link:RelNotes-1.5.3.7.txt[1.5.3.7],
 175  link:RelNotes-1.5.3.6.txt[1.5.3.6],
 176  link:RelNotes-1.5.3.5.txt[1.5.3.5],
 177  link:RelNotes-1.5.3.4.txt[1.5.3.4],
 178  link:RelNotes-1.5.3.3.txt[1.5.3.3],
 179  link:RelNotes-1.5.3.2.txt[1.5.3.2],
 180  link:RelNotes-1.5.3.1.txt[1.5.3.1],
 181  link:RelNotes-1.5.3.txt[1.5.3].
 182
 183* link:v1.5.2.5/git.html[documentation for release 1.5.2.5]
 184
 185* release notes for
 186  link:RelNotes-1.5.2.5.txt[1.5.2.5],
 187  link:RelNotes-1.5.2.4.txt[1.5.2.4],
 188  link:RelNotes-1.5.2.3.txt[1.5.2.3],
 189  link:RelNotes-1.5.2.2.txt[1.5.2.2],
 190  link:RelNotes-1.5.2.1.txt[1.5.2.1],
 191  link:RelNotes-1.5.2.txt[1.5.2].
 192
 193* link:v1.5.1.6/git.html[documentation for release 1.5.1.6]
 194
 195* release notes for
 196  link:RelNotes-1.5.1.6.txt[1.5.1.6],
 197  link:RelNotes-1.5.1.5.txt[1.5.1.5],
 198  link:RelNotes-1.5.1.4.txt[1.5.1.4],
 199  link:RelNotes-1.5.1.3.txt[1.5.1.3],
 200  link:RelNotes-1.5.1.2.txt[1.5.1.2],
 201  link:RelNotes-1.5.1.1.txt[1.5.1.1],
 202  link:RelNotes-1.5.1.txt[1.5.1].
 203
 204* link:v1.5.0.7/git.html[documentation for release 1.5.0.7]
 205
 206* release notes for
 207  link:RelNotes-1.5.0.7.txt[1.5.0.7],
 208  link:RelNotes-1.5.0.6.txt[1.5.0.6],
 209  link:RelNotes-1.5.0.5.txt[1.5.0.5],
 210  link:RelNotes-1.5.0.3.txt[1.5.0.3],
 211  link:RelNotes-1.5.0.2.txt[1.5.0.2],
 212  link:RelNotes-1.5.0.1.txt[1.5.0.1],
 213  link:RelNotes-1.5.0.txt[1.5.0].
 214
 215* documentation for release link:v1.4.4.4/git.html[1.4.4.4],
 216  link:v1.3.3/git.html[1.3.3],
 217  link:v1.2.6/git.html[1.2.6],
 218  link:v1.0.13/git.html[1.0.13].
 219
 220============
 221
 222endif::stalenotes[]
 223
 224OPTIONS
 225-------
 226--version::
 227        Prints the git suite version that the 'git' program came from.
 228
 229--help::
 230        Prints the synopsis and a list of the most commonly used
 231        commands. If the option '--all' or '-a' is given then all
 232        available commands are printed. If a git command is named this
 233        option will bring up the manual page for that command.
 234+
 235Other options are available to control how the manual page is
 236displayed. See linkgit:git-help[1] for more information,
 237because `git --help ...` is converted internally into `git
 238help ...`.
 239
 240-c <name>=<value>::
 241        Pass a configuration parameter to the command. The value
 242        given will override values from configuration files.
 243        The <name> is expected in the same format as listed by
 244        'git config' (subkeys separated by dots).
 245
 246--exec-path::
 247        Path to wherever your core git programs are installed.
 248        This can also be controlled by setting the GIT_EXEC_PATH
 249        environment variable. If no path is given, 'git' will print
 250        the current setting and then exit.
 251
 252--html-path::
 253        Print the path to wherever your git HTML documentation is installed
 254        and exit.
 255
 256-p::
 257--paginate::
 258        Pipe all output into 'less' (or if set, $PAGER) if standard
 259        output is a terminal.  This overrides the `pager.<cmd>`
 260        configuration options (see the "Configuration Mechanism" section
 261        below).
 262
 263--no-pager::
 264        Do not pipe git output into a pager.
 265
 266--git-dir=<path>::
 267        Set the path to the repository. This can also be controlled by
 268        setting the GIT_DIR environment variable. It can be an absolute
 269        path or relative path to current working directory.
 270
 271--work-tree=<path>::
 272        Set the path to the working tree.  The value will not be
 273        used in combination with repositories found automatically in
 274        a .git directory (i.e. $GIT_DIR is not set).
 275        This can also be controlled by setting the GIT_WORK_TREE
 276        environment variable and the core.worktree configuration
 277        variable. It can be an absolute path or relative path to
 278        the directory specified by --git-dir or GIT_DIR.
 279        Note: If --git-dir or GIT_DIR are specified but none of
 280        --work-tree, GIT_WORK_TREE and core.worktree is specified,
 281        the current working directory is regarded as the top directory
 282        of your working tree.
 283
 284--bare::
 285        Treat the repository as a bare repository.  If GIT_DIR
 286        environment is not set, it is set to the current working
 287        directory.
 288
 289--no-replace-objects::
 290        Do not use replacement refs to replace git objects. See
 291        linkgit:git-replace[1] for more information.
 292
 293
 294FURTHER DOCUMENTATION
 295---------------------
 296
 297See the references above to get started using git.  The following is
 298probably more detail than necessary for a first-time user.
 299
 300The link:user-manual.html#git-concepts[git concepts chapter of the
 301user-manual] and linkgit:gitcore-tutorial[7] both provide
 302introductions to the underlying git architecture.
 303
 304See linkgit:gitworkflows[7] for an overview of recommended workflows.
 305
 306See also the link:howto-index.html[howto] documents for some useful
 307examples.
 308
 309The internals are documented in the
 310link:technical/api-index.html[GIT API documentation].
 311
 312GIT COMMANDS
 313------------
 314
 315We divide git into high level ("porcelain") commands and low level
 316("plumbing") commands.
 317
 318High-level commands (porcelain)
 319-------------------------------
 320
 321We separate the porcelain commands into the main commands and some
 322ancillary user utilities.
 323
 324Main porcelain commands
 325~~~~~~~~~~~~~~~~~~~~~~~
 326
 327include::cmds-mainporcelain.txt[]
 328
 329Ancillary Commands
 330~~~~~~~~~~~~~~~~~~
 331Manipulators:
 332
 333include::cmds-ancillarymanipulators.txt[]
 334
 335Interrogators:
 336
 337include::cmds-ancillaryinterrogators.txt[]
 338
 339
 340Interacting with Others
 341~~~~~~~~~~~~~~~~~~~~~~~
 342
 343These commands are to interact with foreign SCM and with other
 344people via patch over e-mail.
 345
 346include::cmds-foreignscminterface.txt[]
 347
 348
 349Low-level commands (plumbing)
 350-----------------------------
 351
 352Although git includes its
 353own porcelain layer, its low-level commands are sufficient to support
 354development of alternative porcelains.  Developers of such porcelains
 355might start by reading about linkgit:git-update-index[1] and
 356linkgit:git-read-tree[1].
 357
 358The interface (input, output, set of options and the semantics)
 359to these low-level commands are meant to be a lot more stable
 360than Porcelain level commands, because these commands are
 361primarily for scripted use.  The interface to Porcelain commands
 362on the other hand are subject to change in order to improve the
 363end user experience.
 364
 365The following description divides
 366the low-level commands into commands that manipulate objects (in
 367the repository, index, and working tree), commands that interrogate and
 368compare objects, and commands that move objects and references between
 369repositories.
 370
 371
 372Manipulation commands
 373~~~~~~~~~~~~~~~~~~~~~
 374
 375include::cmds-plumbingmanipulators.txt[]
 376
 377
 378Interrogation commands
 379~~~~~~~~~~~~~~~~~~~~~~
 380
 381include::cmds-plumbinginterrogators.txt[]
 382
 383In general, the interrogate commands do not touch the files in
 384the working tree.
 385
 386
 387Synching repositories
 388~~~~~~~~~~~~~~~~~~~~~
 389
 390include::cmds-synchingrepositories.txt[]
 391
 392The following are helper commands used by the above; end users
 393typically do not use them directly.
 394
 395include::cmds-synchelpers.txt[]
 396
 397
 398Internal helper commands
 399~~~~~~~~~~~~~~~~~~~~~~~~
 400
 401These are internal helper commands used by other commands; end
 402users typically do not use them directly.
 403
 404include::cmds-purehelpers.txt[]
 405
 406
 407Configuration Mechanism
 408-----------------------
 409
 410Starting from 0.99.9 (actually mid 0.99.8.GIT), `.git/config` file
 411is used to hold per-repository configuration options.  It is a
 412simple text file modeled after `.ini` format familiar to some
 413people.  Here is an example:
 414
 415------------
 416#
 417# A '#' or ';' character indicates a comment.
 418#
 419
 420; core variables
 421[core]
 422        ; Don't trust file modes
 423        filemode = false
 424
 425; user identity
 426[user]
 427        name = "Junio C Hamano"
 428        email = "junkio@twinsun.com"
 429
 430------------
 431
 432Various commands read from the configuration file and adjust
 433their operation accordingly.  See linkgit:git-config[1] for a
 434list.
 435
 436
 437Identifier Terminology
 438----------------------
 439<object>::
 440        Indicates the object name for any type of object.
 441
 442<blob>::
 443        Indicates a blob object name.
 444
 445<tree>::
 446        Indicates a tree object name.
 447
 448<commit>::
 449        Indicates a commit object name.
 450
 451<tree-ish>::
 452        Indicates a tree, commit or tag object name.  A
 453        command that takes a <tree-ish> argument ultimately wants to
 454        operate on a <tree> object but automatically dereferences
 455        <commit> and <tag> objects that point at a <tree>.
 456
 457<commit-ish>::
 458        Indicates a commit or tag object name.  A
 459        command that takes a <commit-ish> argument ultimately wants to
 460        operate on a <commit> object but automatically dereferences
 461        <tag> objects that point at a <commit>.
 462
 463<type>::
 464        Indicates that an object type is required.
 465        Currently one of: `blob`, `tree`, `commit`, or `tag`.
 466
 467<file>::
 468        Indicates a filename - almost always relative to the
 469        root of the tree structure `GIT_INDEX_FILE` describes.
 470
 471Symbolic Identifiers
 472--------------------
 473Any git command accepting any <object> can also use the following
 474symbolic notation:
 475
 476HEAD::
 477        indicates the head of the current branch (i.e. the
 478        contents of `$GIT_DIR/HEAD`).
 479
 480<tag>::
 481        a valid tag 'name'
 482        (i.e. the contents of `$GIT_DIR/refs/tags/<tag>`).
 483
 484<head>::
 485        a valid head 'name'
 486        (i.e. the contents of `$GIT_DIR/refs/heads/<head>`).
 487
 488For a more complete list of ways to spell object names, see
 489"SPECIFYING REVISIONS" section in linkgit:gitrevisions[1].
 490
 491
 492File/Directory Structure
 493------------------------
 494
 495Please see the linkgit:gitrepository-layout[5] document.
 496
 497Read linkgit:githooks[5] for more details about each hook.
 498
 499Higher level SCMs may provide and manage additional information in the
 500`$GIT_DIR`.
 501
 502
 503Terminology
 504-----------
 505Please see linkgit:gitglossary[7].
 506
 507
 508Environment Variables
 509---------------------
 510Various git commands use the following environment variables:
 511
 512The git Repository
 513~~~~~~~~~~~~~~~~~~
 514These environment variables apply to 'all' core git commands. Nb: it
 515is worth noting that they may be used/overridden by SCMS sitting above
 516git so take care if using Cogito etc.
 517
 518'GIT_INDEX_FILE'::
 519        This environment allows the specification of an alternate
 520        index file. If not specified, the default of `$GIT_DIR/index`
 521        is used.
 522
 523'GIT_OBJECT_DIRECTORY'::
 524        If the object storage directory is specified via this
 525        environment variable then the sha1 directories are created
 526        underneath - otherwise the default `$GIT_DIR/objects`
 527        directory is used.
 528
 529'GIT_ALTERNATE_OBJECT_DIRECTORIES'::
 530        Due to the immutable nature of git objects, old objects can be
 531        archived into shared, read-only directories. This variable
 532        specifies a ":" separated (on Windows ";" separated) list
 533        of git object directories which can be used to search for git
 534        objects. New objects will not be written to these directories.
 535
 536'GIT_DIR'::
 537        If the 'GIT_DIR' environment variable is set then it
 538        specifies a path to use instead of the default `.git`
 539        for the base of the repository.
 540
 541'GIT_WORK_TREE'::
 542        Set the path to the working tree.  The value will not be
 543        used in combination with repositories found automatically in
 544        a .git directory (i.e. $GIT_DIR is not set).
 545        This can also be controlled by the '--work-tree' command line
 546        option and the core.worktree configuration variable.
 547
 548'GIT_CEILING_DIRECTORIES'::
 549        This should be a colon-separated list of absolute paths.
 550        If set, it is a list of directories that git should not chdir
 551        up into while looking for a repository directory.
 552        It will not exclude the current working directory or
 553        a GIT_DIR set on the command line or in the environment.
 554        (Useful for excluding slow-loading network directories.)
 555
 556'GIT_DISCOVERY_ACROSS_FILESYSTEM'::
 557        When run in a directory that does not have ".git" repository
 558        directory, git tries to find such a directory in the parent
 559        directories to find the top of the working tree, but by default it
 560        does not cross filesystem boundaries.  This environment variable
 561        can be set to true to tell git not to stop at filesystem
 562        boundaries.  Like 'GIT_CEILING_DIRECTORIES', this will not affect
 563        an explicit repository directory set via 'GIT_DIR' or on the
 564        command line.
 565
 566git Commits
 567~~~~~~~~~~~
 568'GIT_AUTHOR_NAME'::
 569'GIT_AUTHOR_EMAIL'::
 570'GIT_AUTHOR_DATE'::
 571'GIT_COMMITTER_NAME'::
 572'GIT_COMMITTER_EMAIL'::
 573'GIT_COMMITTER_DATE'::
 574'EMAIL'::
 575        see linkgit:git-commit-tree[1]
 576
 577git Diffs
 578~~~~~~~~~
 579'GIT_DIFF_OPTS'::
 580        Only valid setting is "--unified=??" or "-u??" to set the
 581        number of context lines shown when a unified diff is created.
 582        This takes precedence over any "-U" or "--unified" option
 583        value passed on the git diff command line.
 584
 585'GIT_EXTERNAL_DIFF'::
 586        When the environment variable 'GIT_EXTERNAL_DIFF' is set, the
 587        program named by it is called, instead of the diff invocation
 588        described above.  For a path that is added, removed, or modified,
 589        'GIT_EXTERNAL_DIFF' is called with 7 parameters:
 590
 591        path old-file old-hex old-mode new-file new-hex new-mode
 592+
 593where:
 594
 595        <old|new>-file:: are files GIT_EXTERNAL_DIFF can use to read the
 596                         contents of <old|new>,
 597        <old|new>-hex:: are the 40-hexdigit SHA1 hashes,
 598        <old|new>-mode:: are the octal representation of the file modes.
 599
 600+
 601The file parameters can point at the user's working file
 602(e.g. `new-file` in "git-diff-files"), `/dev/null` (e.g. `old-file`
 603when a new file is added), or a temporary file (e.g. `old-file` in the
 604index).  'GIT_EXTERNAL_DIFF' should not worry about unlinking the
 605temporary file --- it is removed when 'GIT_EXTERNAL_DIFF' exits.
 606+
 607For a path that is unmerged, 'GIT_EXTERNAL_DIFF' is called with 1
 608parameter, <path>.
 609
 610other
 611~~~~~
 612'GIT_MERGE_VERBOSITY'::
 613        A number controlling the amount of output shown by
 614        the recursive merge strategy.  Overrides merge.verbosity.
 615        See linkgit:git-merge[1]
 616
 617'GIT_PAGER'::
 618        This environment variable overrides `$PAGER`. If it is set
 619        to an empty string or to the value "cat", git will not launch
 620        a pager.  See also the `core.pager` option in
 621        linkgit:git-config[1].
 622
 623'GIT_SSH'::
 624        If this environment variable is set then 'git fetch'
 625        and 'git push' will use this command instead
 626        of 'ssh' when they need to connect to a remote system.
 627        The '$GIT_SSH' command will be given exactly two arguments:
 628        the 'username@host' (or just 'host') from the URL and the
 629        shell command to execute on that remote system.
 630+
 631To pass options to the program that you want to list in GIT_SSH
 632you will need to wrap the program and options into a shell script,
 633then set GIT_SSH to refer to the shell script.
 634+
 635Usually it is easier to configure any desired options through your
 636personal `.ssh/config` file.  Please consult your ssh documentation
 637for further details.
 638
 639'GIT_FLUSH'::
 640        If this environment variable is set to "1", then commands such
 641        as 'git blame' (in incremental mode), 'git rev-list', 'git log',
 642        and 'git whatchanged' will force a flush of the output stream
 643        after each commit-oriented record have been flushed.   If this
 644        variable is set to "0", the output of these commands will be done
 645        using completely buffered I/O.   If this environment variable is
 646        not set, git will choose buffered or record-oriented flushing
 647        based on whether stdout appears to be redirected to a file or not.
 648
 649'GIT_TRACE'::
 650        If this variable is set to "1", "2" or "true" (comparison
 651        is case insensitive), git will print `trace:` messages on
 652        stderr telling about alias expansion, built-in command
 653        execution and external command execution.
 654        If this variable is set to an integer value greater than 1
 655        and lower than 10 (strictly) then git will interpret this
 656        value as an open file descriptor and will try to write the
 657        trace messages into this file descriptor.
 658        Alternatively, if this variable is set to an absolute path
 659        (starting with a '/' character), git will interpret this
 660        as a file path and will try to write the trace messages
 661        into it.
 662
 663Discussion[[Discussion]]
 664------------------------
 665
 666More detail on the following is available from the
 667link:user-manual.html#git-concepts[git concepts chapter of the
 668user-manual] and linkgit:gitcore-tutorial[7].
 669
 670A git project normally consists of a working directory with a ".git"
 671subdirectory at the top level.  The .git directory contains, among other
 672things, a compressed object database representing the complete history
 673of the project, an "index" file which links that history to the current
 674contents of the working tree, and named pointers into that history such
 675as tags and branch heads.
 676
 677The object database contains objects of three main types: blobs, which
 678hold file data; trees, which point to blobs and other trees to build up
 679directory hierarchies; and commits, which each reference a single tree
 680and some number of parent commits.
 681
 682The commit, equivalent to what other systems call a "changeset" or
 683"version", represents a step in the project's history, and each parent
 684represents an immediately preceding step.  Commits with more than one
 685parent represent merges of independent lines of development.
 686
 687All objects are named by the SHA1 hash of their contents, normally
 688written as a string of 40 hex digits.  Such names are globally unique.
 689The entire history leading up to a commit can be vouched for by signing
 690just that commit.  A fourth object type, the tag, is provided for this
 691purpose.
 692
 693When first created, objects are stored in individual files, but for
 694efficiency may later be compressed together into "pack files".
 695
 696Named pointers called refs mark interesting points in history.  A ref
 697may contain the SHA1 name of an object or the name of another ref.  Refs
 698with names beginning `ref/head/` contain the SHA1 name of the most
 699recent commit (or "head") of a branch under development.  SHA1 names of
 700tags of interest are stored under `ref/tags/`.  A special ref named
 701`HEAD` contains the name of the currently checked-out branch.
 702
 703The index file is initialized with a list of all paths and, for each
 704path, a blob object and a set of attributes.  The blob object represents
 705the contents of the file as of the head of the current branch.  The
 706attributes (last modified time, size, etc.) are taken from the
 707corresponding file in the working tree.  Subsequent changes to the
 708working tree can be found by comparing these attributes.  The index may
 709be updated with new content, and new commits may be created from the
 710content stored in the index.
 711
 712The index is also capable of storing multiple entries (called "stages")
 713for a given pathname.  These stages are used to hold the various
 714unmerged version of a file when a merge is in progress.
 715
 716Authors
 717-------
 718* git's founding father is Linus Torvalds <torvalds@osdl.org>.
 719* The current git nurse is Junio C Hamano <gitster@pobox.com>.
 720* The git potty was written by Andreas Ericsson <ae@op5.se>.
 721* General upbringing is handled by the git-list <git@vger.kernel.org>.
 722
 723Documentation
 724--------------
 725The documentation for git suite was started by David Greaves
 726<david@dgreaves.com>, and later enhanced greatly by the
 727contributors on the git-list <git@vger.kernel.org>.
 728
 729SEE ALSO
 730--------
 731linkgit:gittutorial[7], linkgit:gittutorial-2[7],
 732link:everyday.html[Everyday Git], linkgit:gitcvs-migration[7],
 733linkgit:gitglossary[7], linkgit:gitcore-tutorial[7],
 734linkgit:gitcli[7], link:user-manual.html[The Git User's Manual],
 735linkgit:gitworkflows[7]
 736
 737GIT
 738---
 739Part of the linkgit:git[1] suite