Documentation / git.txton commit Git 1.7.2.1 (2aedccd)
   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:v1.7.2.1/git.html[documentation for release 1.7.2.1]
  48
  49* release notes for
  50  link:RelNotes-1.7.2.1.txt[1.7.2.1],
  51  link:RelNotes-1.7.2.txt[1.7.2].
  52
  53* link:v1.7.1.2/git.html[documentation for release 1.7.1.2]
  54
  55* release notes for
  56  link:RelNotes-1.7.1.2.txt[1.7.1.2],
  57  link:RelNotes-1.7.1.1.txt[1.7.1.1],
  58  link:RelNotes-1.7.1.txt[1.7.1].
  59
  60* link:v1.7.0.7/git.html[documentation for release 1.7.0.7]
  61
  62* release notes for
  63  link:RelNotes-1.7.0.7.txt[1.7.0.7],
  64  link:RelNotes-1.7.0.6.txt[1.7.0.6],
  65  link:RelNotes-1.7.0.5.txt[1.7.0.5],
  66  link:RelNotes-1.7.0.4.txt[1.7.0.4],
  67  link:RelNotes-1.7.0.3.txt[1.7.0.3],
  68  link:RelNotes-1.7.0.2.txt[1.7.0.2],
  69  link:RelNotes-1.7.0.1.txt[1.7.0.1],
  70  link:RelNotes-1.7.0.txt[1.7.0].
  71
  72* link:v1.6.6.2/git.html[documentation for release 1.6.6.2]
  73
  74* release notes for
  75  link:RelNotes-1.6.6.2.txt[1.6.6.2],
  76  link:RelNotes-1.6.6.1.txt[1.6.6.1],
  77  link:RelNotes-1.6.6.txt[1.6.6].
  78
  79* link:v1.6.5.8/git.html[documentation for release 1.6.5.8]
  80
  81* release notes for
  82  link:RelNotes-1.6.5.8.txt[1.6.5.8],
  83  link:RelNotes-1.6.5.7.txt[1.6.5.7],
  84  link:RelNotes-1.6.5.6.txt[1.6.5.6],
  85  link:RelNotes-1.6.5.5.txt[1.6.5.5],
  86  link:RelNotes-1.6.5.4.txt[1.6.5.4],
  87  link:RelNotes-1.6.5.3.txt[1.6.5.3],
  88  link:RelNotes-1.6.5.2.txt[1.6.5.2],
  89  link:RelNotes-1.6.5.1.txt[1.6.5.1],
  90  link:RelNotes-1.6.5.txt[1.6.5].
  91
  92* link:v1.6.4.4/git.html[documentation for release 1.6.4.4]
  93
  94* release notes for
  95  link:RelNotes-1.6.4.4.txt[1.6.4.4],
  96  link:RelNotes-1.6.4.3.txt[1.6.4.3],
  97  link:RelNotes-1.6.4.2.txt[1.6.4.2],
  98  link:RelNotes-1.6.4.1.txt[1.6.4.1],
  99  link:RelNotes-1.6.4.txt[1.6.4].
 100
 101* link:v1.6.3.4/git.html[documentation for release 1.6.3.4]
 102
 103* release notes for
 104  link:RelNotes-1.6.3.4.txt[1.6.3.4],
 105  link:RelNotes-1.6.3.3.txt[1.6.3.3],
 106  link:RelNotes-1.6.3.2.txt[1.6.3.2],
 107  link:RelNotes-1.6.3.1.txt[1.6.3.1],
 108  link:RelNotes-1.6.3.txt[1.6.3].
 109
 110* release notes for
 111  link:RelNotes-1.6.2.5.txt[1.6.2.5],
 112  link:RelNotes-1.6.2.4.txt[1.6.2.4],
 113  link:RelNotes-1.6.2.3.txt[1.6.2.3],
 114  link:RelNotes-1.6.2.2.txt[1.6.2.2],
 115  link:RelNotes-1.6.2.1.txt[1.6.2.1],
 116  link:RelNotes-1.6.2.txt[1.6.2].
 117
 118* link:v1.6.1.3/git.html[documentation for release 1.6.1.3]
 119
 120* release notes for
 121  link:RelNotes-1.6.1.3.txt[1.6.1.3],
 122  link:RelNotes-1.6.1.2.txt[1.6.1.2],
 123  link:RelNotes-1.6.1.1.txt[1.6.1.1],
 124  link:RelNotes-1.6.1.txt[1.6.1].
 125
 126* link:v1.6.0.6/git.html[documentation for release 1.6.0.6]
 127
 128* release notes for
 129  link:RelNotes-1.6.0.6.txt[1.6.0.6],
 130  link:RelNotes-1.6.0.5.txt[1.6.0.5],
 131  link:RelNotes-1.6.0.4.txt[1.6.0.4],
 132  link:RelNotes-1.6.0.3.txt[1.6.0.3],
 133  link:RelNotes-1.6.0.2.txt[1.6.0.2],
 134  link:RelNotes-1.6.0.1.txt[1.6.0.1],
 135  link:RelNotes-1.6.0.txt[1.6.0].
 136
 137* link:v1.5.6.6/git.html[documentation for release 1.5.6.6]
 138
 139* release notes for
 140  link:RelNotes-1.5.6.6.txt[1.5.6.6],
 141  link:RelNotes-1.5.6.5.txt[1.5.6.5],
 142  link:RelNotes-1.5.6.4.txt[1.5.6.4],
 143  link:RelNotes-1.5.6.3.txt[1.5.6.3],
 144  link:RelNotes-1.5.6.2.txt[1.5.6.2],
 145  link:RelNotes-1.5.6.1.txt[1.5.6.1],
 146  link:RelNotes-1.5.6.txt[1.5.6].
 147
 148* link:v1.5.5.6/git.html[documentation for release 1.5.5.6]
 149
 150* release notes for
 151  link:RelNotes-1.5.5.6.txt[1.5.5.6],
 152  link:RelNotes-1.5.5.5.txt[1.5.5.5],
 153  link:RelNotes-1.5.5.4.txt[1.5.5.4],
 154  link:RelNotes-1.5.5.3.txt[1.5.5.3],
 155  link:RelNotes-1.5.5.2.txt[1.5.5.2],
 156  link:RelNotes-1.5.5.1.txt[1.5.5.1],
 157  link:RelNotes-1.5.5.txt[1.5.5].
 158
 159* link:v1.5.4.7/git.html[documentation for release 1.5.4.7]
 160
 161* release notes for
 162  link:RelNotes-1.5.4.7.txt[1.5.4.7],
 163  link:RelNotes-1.5.4.6.txt[1.5.4.6],
 164  link:RelNotes-1.5.4.5.txt[1.5.4.5],
 165  link:RelNotes-1.5.4.4.txt[1.5.4.4],
 166  link:RelNotes-1.5.4.3.txt[1.5.4.3],
 167  link:RelNotes-1.5.4.2.txt[1.5.4.2],
 168  link:RelNotes-1.5.4.1.txt[1.5.4.1],
 169  link:RelNotes-1.5.4.txt[1.5.4].
 170
 171* link:v1.5.3.8/git.html[documentation for release 1.5.3.8]
 172
 173* release notes for
 174  link:RelNotes-1.5.3.8.txt[1.5.3.8],
 175  link:RelNotes-1.5.3.7.txt[1.5.3.7],
 176  link:RelNotes-1.5.3.6.txt[1.5.3.6],
 177  link:RelNotes-1.5.3.5.txt[1.5.3.5],
 178  link:RelNotes-1.5.3.4.txt[1.5.3.4],
 179  link:RelNotes-1.5.3.3.txt[1.5.3.3],
 180  link:RelNotes-1.5.3.2.txt[1.5.3.2],
 181  link:RelNotes-1.5.3.1.txt[1.5.3.1],
 182  link:RelNotes-1.5.3.txt[1.5.3].
 183
 184* link:v1.5.2.5/git.html[documentation for release 1.5.2.5]
 185
 186* release notes for
 187  link:RelNotes-1.5.2.5.txt[1.5.2.5],
 188  link:RelNotes-1.5.2.4.txt[1.5.2.4],
 189  link:RelNotes-1.5.2.3.txt[1.5.2.3],
 190  link:RelNotes-1.5.2.2.txt[1.5.2.2],
 191  link:RelNotes-1.5.2.1.txt[1.5.2.1],
 192  link:RelNotes-1.5.2.txt[1.5.2].
 193
 194* link:v1.5.1.6/git.html[documentation for release 1.5.1.6]
 195
 196* release notes for
 197  link:RelNotes-1.5.1.6.txt[1.5.1.6],
 198  link:RelNotes-1.5.1.5.txt[1.5.1.5],
 199  link:RelNotes-1.5.1.4.txt[1.5.1.4],
 200  link:RelNotes-1.5.1.3.txt[1.5.1.3],
 201  link:RelNotes-1.5.1.2.txt[1.5.1.2],
 202  link:RelNotes-1.5.1.1.txt[1.5.1.1],
 203  link:RelNotes-1.5.1.txt[1.5.1].
 204
 205* link:v1.5.0.7/git.html[documentation for release 1.5.0.7]
 206
 207* release notes for
 208  link:RelNotes-1.5.0.7.txt[1.5.0.7],
 209  link:RelNotes-1.5.0.6.txt[1.5.0.6],
 210  link:RelNotes-1.5.0.5.txt[1.5.0.5],
 211  link:RelNotes-1.5.0.3.txt[1.5.0.3],
 212  link:RelNotes-1.5.0.2.txt[1.5.0.2],
 213  link:RelNotes-1.5.0.1.txt[1.5.0.1],
 214  link:RelNotes-1.5.0.txt[1.5.0].
 215
 216* documentation for release link:v1.4.4.4/git.html[1.4.4.4],
 217  link:v1.3.3/git.html[1.3.3],
 218  link:v1.2.6/git.html[1.2.6],
 219  link:v1.0.13/git.html[1.0.13].
 220
 221============
 222
 223endif::stalenotes[]
 224
 225OPTIONS
 226-------
 227--version::
 228        Prints the git suite version that the 'git' program came from.
 229
 230--help::
 231        Prints the synopsis and a list of the most commonly used
 232        commands. If the option '--all' or '-a' is given then all
 233        available commands are printed. If a git command is named this
 234        option will bring up the manual page for that command.
 235+
 236Other options are available to control how the manual page is
 237displayed. See linkgit:git-help[1] for more information,
 238because `git --help ...` is converted internally into `git
 239help ...`.
 240
 241-c <name>=<value>::
 242        Pass a configuration parameter to the command. The value
 243        given will override values from configuration files.
 244        The <name> is expected in the same format as listed by
 245        'git config' (subkeys separated by dots).
 246
 247--exec-path::
 248        Path to wherever your core git programs are installed.
 249        This can also be controlled by setting the GIT_EXEC_PATH
 250        environment variable. If no path is given, 'git' will print
 251        the current setting and then exit.
 252
 253--html-path::
 254        Print the path to wherever your git HTML documentation is installed
 255        and exit.
 256
 257-p::
 258--paginate::
 259        Pipe all output into 'less' (or if set, $PAGER) if standard
 260        output is a terminal.  This overrides the `pager.<cmd>`
 261        configuration options (see the "Configuration Mechanism" section
 262        below).
 263
 264--no-pager::
 265        Do not pipe git output into a pager.
 266
 267--git-dir=<path>::
 268        Set the path to the repository. This can also be controlled by
 269        setting the GIT_DIR environment variable. It can be an absolute
 270        path or relative path to current working directory.
 271
 272--work-tree=<path>::
 273        Set the path to the working tree.  The value will not be
 274        used in combination with repositories found automatically in
 275        a .git directory (i.e. $GIT_DIR is not set).
 276        This can also be controlled by setting the GIT_WORK_TREE
 277        environment variable and the core.worktree configuration
 278        variable. It can be an absolute path or relative path to
 279        the directory specified by --git-dir or GIT_DIR.
 280        Note: If --git-dir or GIT_DIR are specified but none of
 281        --work-tree, GIT_WORK_TREE and core.worktree is specified,
 282        the current working directory is regarded as the top directory
 283        of your working tree.
 284
 285--bare::
 286        Treat the repository as a bare repository.  If GIT_DIR
 287        environment is not set, it is set to the current working
 288        directory.
 289
 290--no-replace-objects::
 291        Do not use replacement refs to replace git objects. See
 292        linkgit:git-replace[1] for more information.
 293
 294
 295FURTHER DOCUMENTATION
 296---------------------
 297
 298See the references above to get started using git.  The following is
 299probably more detail than necessary for a first-time user.
 300
 301The link:user-manual.html#git-concepts[git concepts chapter of the
 302user-manual] and linkgit:gitcore-tutorial[7] both provide
 303introductions to the underlying git architecture.
 304
 305See linkgit:gitworkflows[7] for an overview of recommended workflows.
 306
 307See also the link:howto-index.html[howto] documents for some useful
 308examples.
 309
 310The internals are documented in the
 311link:technical/api-index.html[GIT API documentation].
 312
 313GIT COMMANDS
 314------------
 315
 316We divide git into high level ("porcelain") commands and low level
 317("plumbing") commands.
 318
 319High-level commands (porcelain)
 320-------------------------------
 321
 322We separate the porcelain commands into the main commands and some
 323ancillary user utilities.
 324
 325Main porcelain commands
 326~~~~~~~~~~~~~~~~~~~~~~~
 327
 328include::cmds-mainporcelain.txt[]
 329
 330Ancillary Commands
 331~~~~~~~~~~~~~~~~~~
 332Manipulators:
 333
 334include::cmds-ancillarymanipulators.txt[]
 335
 336Interrogators:
 337
 338include::cmds-ancillaryinterrogators.txt[]
 339
 340
 341Interacting with Others
 342~~~~~~~~~~~~~~~~~~~~~~~
 343
 344These commands are to interact with foreign SCM and with other
 345people via patch over e-mail.
 346
 347include::cmds-foreignscminterface.txt[]
 348
 349
 350Low-level commands (plumbing)
 351-----------------------------
 352
 353Although git includes its
 354own porcelain layer, its low-level commands are sufficient to support
 355development of alternative porcelains.  Developers of such porcelains
 356might start by reading about linkgit:git-update-index[1] and
 357linkgit:git-read-tree[1].
 358
 359The interface (input, output, set of options and the semantics)
 360to these low-level commands are meant to be a lot more stable
 361than Porcelain level commands, because these commands are
 362primarily for scripted use.  The interface to Porcelain commands
 363on the other hand are subject to change in order to improve the
 364end user experience.
 365
 366The following description divides
 367the low-level commands into commands that manipulate objects (in
 368the repository, index, and working tree), commands that interrogate and
 369compare objects, and commands that move objects and references between
 370repositories.
 371
 372
 373Manipulation commands
 374~~~~~~~~~~~~~~~~~~~~~
 375
 376include::cmds-plumbingmanipulators.txt[]
 377
 378
 379Interrogation commands
 380~~~~~~~~~~~~~~~~~~~~~~
 381
 382include::cmds-plumbinginterrogators.txt[]
 383
 384In general, the interrogate commands do not touch the files in
 385the working tree.
 386
 387
 388Synching repositories
 389~~~~~~~~~~~~~~~~~~~~~
 390
 391include::cmds-synchingrepositories.txt[]
 392
 393The following are helper commands used by the above; end users
 394typically do not use them directly.
 395
 396include::cmds-synchelpers.txt[]
 397
 398
 399Internal helper commands
 400~~~~~~~~~~~~~~~~~~~~~~~~
 401
 402These are internal helper commands used by other commands; end
 403users typically do not use them directly.
 404
 405include::cmds-purehelpers.txt[]
 406
 407
 408Configuration Mechanism
 409-----------------------
 410
 411Starting from 0.99.9 (actually mid 0.99.8.GIT), `.git/config` file
 412is used to hold per-repository configuration options.  It is a
 413simple text file modeled after `.ini` format familiar to some
 414people.  Here is an example:
 415
 416------------
 417#
 418# A '#' or ';' character indicates a comment.
 419#
 420
 421; core variables
 422[core]
 423        ; Don't trust file modes
 424        filemode = false
 425
 426; user identity
 427[user]
 428        name = "Junio C Hamano"
 429        email = "junkio@twinsun.com"
 430
 431------------
 432
 433Various commands read from the configuration file and adjust
 434their operation accordingly.  See linkgit:git-config[1] for a
 435list.
 436
 437
 438Identifier Terminology
 439----------------------
 440<object>::
 441        Indicates the object name for any type of object.
 442
 443<blob>::
 444        Indicates a blob object name.
 445
 446<tree>::
 447        Indicates a tree object name.
 448
 449<commit>::
 450        Indicates a commit object name.
 451
 452<tree-ish>::
 453        Indicates a tree, commit or tag object name.  A
 454        command that takes a <tree-ish> argument ultimately wants to
 455        operate on a <tree> object but automatically dereferences
 456        <commit> and <tag> objects that point at a <tree>.
 457
 458<commit-ish>::
 459        Indicates a commit or tag object name.  A
 460        command that takes a <commit-ish> argument ultimately wants to
 461        operate on a <commit> object but automatically dereferences
 462        <tag> objects that point at a <commit>.
 463
 464<type>::
 465        Indicates that an object type is required.
 466        Currently one of: `blob`, `tree`, `commit`, or `tag`.
 467
 468<file>::
 469        Indicates a filename - almost always relative to the
 470        root of the tree structure `GIT_INDEX_FILE` describes.
 471
 472Symbolic Identifiers
 473--------------------
 474Any git command accepting any <object> can also use the following
 475symbolic notation:
 476
 477HEAD::
 478        indicates the head of the current branch (i.e. the
 479        contents of `$GIT_DIR/HEAD`).
 480
 481<tag>::
 482        a valid tag 'name'
 483        (i.e. the contents of `$GIT_DIR/refs/tags/<tag>`).
 484
 485<head>::
 486        a valid head 'name'
 487        (i.e. the contents of `$GIT_DIR/refs/heads/<head>`).
 488
 489For a more complete list of ways to spell object names, see
 490"SPECIFYING REVISIONS" section in linkgit:gitrevisions[1].
 491
 492
 493File/Directory Structure
 494------------------------
 495
 496Please see the linkgit:gitrepository-layout[5] document.
 497
 498Read linkgit:githooks[5] for more details about each hook.
 499
 500Higher level SCMs may provide and manage additional information in the
 501`$GIT_DIR`.
 502
 503
 504Terminology
 505-----------
 506Please see linkgit:gitglossary[7].
 507
 508
 509Environment Variables
 510---------------------
 511Various git commands use the following environment variables:
 512
 513The git Repository
 514~~~~~~~~~~~~~~~~~~
 515These environment variables apply to 'all' core git commands. Nb: it
 516is worth noting that they may be used/overridden by SCMS sitting above
 517git so take care if using Cogito etc.
 518
 519'GIT_INDEX_FILE'::
 520        This environment allows the specification of an alternate
 521        index file. If not specified, the default of `$GIT_DIR/index`
 522        is used.
 523
 524'GIT_OBJECT_DIRECTORY'::
 525        If the object storage directory is specified via this
 526        environment variable then the sha1 directories are created
 527        underneath - otherwise the default `$GIT_DIR/objects`
 528        directory is used.
 529
 530'GIT_ALTERNATE_OBJECT_DIRECTORIES'::
 531        Due to the immutable nature of git objects, old objects can be
 532        archived into shared, read-only directories. This variable
 533        specifies a ":" separated (on Windows ";" separated) list
 534        of git object directories which can be used to search for git
 535        objects. New objects will not be written to these directories.
 536
 537'GIT_DIR'::
 538        If the 'GIT_DIR' environment variable is set then it
 539        specifies a path to use instead of the default `.git`
 540        for the base of the repository.
 541
 542'GIT_WORK_TREE'::
 543        Set the path to the working tree.  The value will not be
 544        used in combination with repositories found automatically in
 545        a .git directory (i.e. $GIT_DIR is not set).
 546        This can also be controlled by the '--work-tree' command line
 547        option and the core.worktree configuration variable.
 548
 549'GIT_CEILING_DIRECTORIES'::
 550        This should be a colon-separated list of absolute paths.
 551        If set, it is a list of directories that git should not chdir
 552        up into while looking for a repository directory.
 553        It will not exclude the current working directory or
 554        a GIT_DIR set on the command line or in the environment.
 555        (Useful for excluding slow-loading network directories.)
 556
 557'GIT_DISCOVERY_ACROSS_FILESYSTEM'::
 558        When run in a directory that does not have ".git" repository
 559        directory, git tries to find such a directory in the parent
 560        directories to find the top of the working tree, but by default it
 561        does not cross filesystem boundaries.  This environment variable
 562        can be set to true to tell git not to stop at filesystem
 563        boundaries.  Like 'GIT_CEILING_DIRECTORIES', this will not affect
 564        an explicit repository directory set via 'GIT_DIR' or on the
 565        command line.
 566
 567git Commits
 568~~~~~~~~~~~
 569'GIT_AUTHOR_NAME'::
 570'GIT_AUTHOR_EMAIL'::
 571'GIT_AUTHOR_DATE'::
 572'GIT_COMMITTER_NAME'::
 573'GIT_COMMITTER_EMAIL'::
 574'GIT_COMMITTER_DATE'::
 575'EMAIL'::
 576        see linkgit:git-commit-tree[1]
 577
 578git Diffs
 579~~~~~~~~~
 580'GIT_DIFF_OPTS'::
 581        Only valid setting is "--unified=??" or "-u??" to set the
 582        number of context lines shown when a unified diff is created.
 583        This takes precedence over any "-U" or "--unified" option
 584        value passed on the git diff command line.
 585
 586'GIT_EXTERNAL_DIFF'::
 587        When the environment variable 'GIT_EXTERNAL_DIFF' is set, the
 588        program named by it is called, instead of the diff invocation
 589        described above.  For a path that is added, removed, or modified,
 590        'GIT_EXTERNAL_DIFF' is called with 7 parameters:
 591
 592        path old-file old-hex old-mode new-file new-hex new-mode
 593+
 594where:
 595
 596        <old|new>-file:: are files GIT_EXTERNAL_DIFF can use to read the
 597                         contents of <old|new>,
 598        <old|new>-hex:: are the 40-hexdigit SHA1 hashes,
 599        <old|new>-mode:: are the octal representation of the file modes.
 600
 601+
 602The file parameters can point at the user's working file
 603(e.g. `new-file` in "git-diff-files"), `/dev/null` (e.g. `old-file`
 604when a new file is added), or a temporary file (e.g. `old-file` in the
 605index).  'GIT_EXTERNAL_DIFF' should not worry about unlinking the
 606temporary file --- it is removed when 'GIT_EXTERNAL_DIFF' exits.
 607+
 608For a path that is unmerged, 'GIT_EXTERNAL_DIFF' is called with 1
 609parameter, <path>.
 610
 611other
 612~~~~~
 613'GIT_MERGE_VERBOSITY'::
 614        A number controlling the amount of output shown by
 615        the recursive merge strategy.  Overrides merge.verbosity.
 616        See linkgit:git-merge[1]
 617
 618'GIT_PAGER'::
 619        This environment variable overrides `$PAGER`. If it is set
 620        to an empty string or to the value "cat", git will not launch
 621        a pager.  See also the `core.pager` option in
 622        linkgit:git-config[1].
 623
 624'GIT_SSH'::
 625        If this environment variable is set then 'git fetch'
 626        and 'git push' will use this command instead
 627        of 'ssh' when they need to connect to a remote system.
 628        The '$GIT_SSH' command will be given exactly two arguments:
 629        the 'username@host' (or just 'host') from the URL and the
 630        shell command to execute on that remote system.
 631+
 632To pass options to the program that you want to list in GIT_SSH
 633you will need to wrap the program and options into a shell script,
 634then set GIT_SSH to refer to the shell script.
 635+
 636Usually it is easier to configure any desired options through your
 637personal `.ssh/config` file.  Please consult your ssh documentation
 638for further details.
 639
 640'GIT_FLUSH'::
 641        If this environment variable is set to "1", then commands such
 642        as 'git blame' (in incremental mode), 'git rev-list', 'git log',
 643        and 'git whatchanged' will force a flush of the output stream
 644        after each commit-oriented record have been flushed.   If this
 645        variable is set to "0", the output of these commands will be done
 646        using completely buffered I/O.   If this environment variable is
 647        not set, git will choose buffered or record-oriented flushing
 648        based on whether stdout appears to be redirected to a file or not.
 649
 650'GIT_TRACE'::
 651        If this variable is set to "1", "2" or "true" (comparison
 652        is case insensitive), git will print `trace:` messages on
 653        stderr telling about alias expansion, built-in command
 654        execution and external command execution.
 655        If this variable is set to an integer value greater than 1
 656        and lower than 10 (strictly) then git will interpret this
 657        value as an open file descriptor and will try to write the
 658        trace messages into this file descriptor.
 659        Alternatively, if this variable is set to an absolute path
 660        (starting with a '/' character), git will interpret this
 661        as a file path and will try to write the trace messages
 662        into it.
 663
 664Discussion[[Discussion]]
 665------------------------
 666
 667More detail on the following is available from the
 668link:user-manual.html#git-concepts[git concepts chapter of the
 669user-manual] and linkgit:gitcore-tutorial[7].
 670
 671A git project normally consists of a working directory with a ".git"
 672subdirectory at the top level.  The .git directory contains, among other
 673things, a compressed object database representing the complete history
 674of the project, an "index" file which links that history to the current
 675contents of the working tree, and named pointers into that history such
 676as tags and branch heads.
 677
 678The object database contains objects of three main types: blobs, which
 679hold file data; trees, which point to blobs and other trees to build up
 680directory hierarchies; and commits, which each reference a single tree
 681and some number of parent commits.
 682
 683The commit, equivalent to what other systems call a "changeset" or
 684"version", represents a step in the project's history, and each parent
 685represents an immediately preceding step.  Commits with more than one
 686parent represent merges of independent lines of development.
 687
 688All objects are named by the SHA1 hash of their contents, normally
 689written as a string of 40 hex digits.  Such names are globally unique.
 690The entire history leading up to a commit can be vouched for by signing
 691just that commit.  A fourth object type, the tag, is provided for this
 692purpose.
 693
 694When first created, objects are stored in individual files, but for
 695efficiency may later be compressed together into "pack files".
 696
 697Named pointers called refs mark interesting points in history.  A ref
 698may contain the SHA1 name of an object or the name of another ref.  Refs
 699with names beginning `ref/head/` contain the SHA1 name of the most
 700recent commit (or "head") of a branch under development.  SHA1 names of
 701tags of interest are stored under `ref/tags/`.  A special ref named
 702`HEAD` contains the name of the currently checked-out branch.
 703
 704The index file is initialized with a list of all paths and, for each
 705path, a blob object and a set of attributes.  The blob object represents
 706the contents of the file as of the head of the current branch.  The
 707attributes (last modified time, size, etc.) are taken from the
 708corresponding file in the working tree.  Subsequent changes to the
 709working tree can be found by comparing these attributes.  The index may
 710be updated with new content, and new commits may be created from the
 711content stored in the index.
 712
 713The index is also capable of storing multiple entries (called "stages")
 714for a given pathname.  These stages are used to hold the various
 715unmerged version of a file when a merge is in progress.
 716
 717Authors
 718-------
 719* git's founding father is Linus Torvalds <torvalds@osdl.org>.
 720* The current git nurse is Junio C Hamano <gitster@pobox.com>.
 721* The git potty was written by Andreas Ericsson <ae@op5.se>.
 722* General upbringing is handled by the git-list <git@vger.kernel.org>.
 723
 724Documentation
 725--------------
 726The documentation for git suite was started by David Greaves
 727<david@dgreaves.com>, and later enhanced greatly by the
 728contributors on the git-list <git@vger.kernel.org>.
 729
 730SEE ALSO
 731--------
 732linkgit:gittutorial[7], linkgit:gittutorial-2[7],
 733link:everyday.html[Everyday Git], linkgit:gitcvs-migration[7],
 734linkgit:gitglossary[7], linkgit:gitcore-tutorial[7],
 735linkgit:gitcli[7], link:user-manual.html[The Git User's Manual],
 736linkgit:gitworkflows[7]
 737
 738GIT
 739---
 740Part of the linkgit:git[1] suite