Documentation / git.txton commit Merge branch 'jc/diff-merge-base-multi' (4cd1b99)
   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:v1.7.1.1/git.html[documentation for release 1.7.1.1]
  48
  49* release notes for
  50  link:RelNotes-1.7.1.1.txt[1.7.1.1],
  51  link:RelNotes-1.7.1.txt[1.7.1].
  52
  53* link:v1.7.0.6/git.html[documentation for release 1.7.0.6]
  54
  55* release notes for
  56  link:RelNotes-1.7.0.6.txt[1.7.0.6],
  57  link:RelNotes-1.7.0.5.txt[1.7.0.5],
  58  link:RelNotes-1.7.0.4.txt[1.7.0.4],
  59  link:RelNotes-1.7.0.3.txt[1.7.0.3],
  60  link:RelNotes-1.7.0.2.txt[1.7.0.2],
  61  link:RelNotes-1.7.0.1.txt[1.7.0.1],
  62  link:RelNotes-1.7.0.txt[1.7.0].
  63
  64* link:v1.6.6.2/git.html[documentation for release 1.6.6.2]
  65
  66* release notes for
  67  link:RelNotes-1.6.6.2.txt[1.6.6.2],
  68  link:RelNotes-1.6.6.1.txt[1.6.6.1],
  69  link:RelNotes-1.6.6.txt[1.6.6].
  70
  71* link:v1.6.5.8/git.html[documentation for release 1.6.5.8]
  72
  73* release notes for
  74  link:RelNotes-1.6.5.8.txt[1.6.5.8],
  75  link:RelNotes-1.6.5.7.txt[1.6.5.7],
  76  link:RelNotes-1.6.5.6.txt[1.6.5.6],
  77  link:RelNotes-1.6.5.5.txt[1.6.5.5],
  78  link:RelNotes-1.6.5.4.txt[1.6.5.4],
  79  link:RelNotes-1.6.5.3.txt[1.6.5.3],
  80  link:RelNotes-1.6.5.2.txt[1.6.5.2],
  81  link:RelNotes-1.6.5.1.txt[1.6.5.1],
  82  link:RelNotes-1.6.5.txt[1.6.5].
  83
  84* link:v1.6.4.4/git.html[documentation for release 1.6.4.4]
  85
  86* release notes for
  87  link:RelNotes-1.6.4.4.txt[1.6.4.4],
  88  link:RelNotes-1.6.4.3.txt[1.6.4.3],
  89  link:RelNotes-1.6.4.2.txt[1.6.4.2],
  90  link:RelNotes-1.6.4.1.txt[1.6.4.1],
  91  link:RelNotes-1.6.4.txt[1.6.4].
  92
  93* link:v1.6.3.4/git.html[documentation for release 1.6.3.4]
  94
  95* release notes for
  96  link:RelNotes-1.6.3.4.txt[1.6.3.4],
  97  link:RelNotes-1.6.3.3.txt[1.6.3.3],
  98  link:RelNotes-1.6.3.2.txt[1.6.3.2],
  99  link:RelNotes-1.6.3.1.txt[1.6.3.1],
 100  link:RelNotes-1.6.3.txt[1.6.3].
 101
 102* release notes for
 103  link:RelNotes-1.6.2.5.txt[1.6.2.5],
 104  link:RelNotes-1.6.2.4.txt[1.6.2.4],
 105  link:RelNotes-1.6.2.3.txt[1.6.2.3],
 106  link:RelNotes-1.6.2.2.txt[1.6.2.2],
 107  link:RelNotes-1.6.2.1.txt[1.6.2.1],
 108  link:RelNotes-1.6.2.txt[1.6.2].
 109
 110* link:v1.6.1.3/git.html[documentation for release 1.6.1.3]
 111
 112* release notes for
 113  link:RelNotes-1.6.1.3.txt[1.6.1.3],
 114  link:RelNotes-1.6.1.2.txt[1.6.1.2],
 115  link:RelNotes-1.6.1.1.txt[1.6.1.1],
 116  link:RelNotes-1.6.1.txt[1.6.1].
 117
 118* link:v1.6.0.6/git.html[documentation for release 1.6.0.6]
 119
 120* release notes for
 121  link:RelNotes-1.6.0.6.txt[1.6.0.6],
 122  link:RelNotes-1.6.0.5.txt[1.6.0.5],
 123  link:RelNotes-1.6.0.4.txt[1.6.0.4],
 124  link:RelNotes-1.6.0.3.txt[1.6.0.3],
 125  link:RelNotes-1.6.0.2.txt[1.6.0.2],
 126  link:RelNotes-1.6.0.1.txt[1.6.0.1],
 127  link:RelNotes-1.6.0.txt[1.6.0].
 128
 129* link:v1.5.6.6/git.html[documentation for release 1.5.6.6]
 130
 131* release notes for
 132  link:RelNotes-1.5.6.6.txt[1.5.6.6],
 133  link:RelNotes-1.5.6.5.txt[1.5.6.5],
 134  link:RelNotes-1.5.6.4.txt[1.5.6.4],
 135  link:RelNotes-1.5.6.3.txt[1.5.6.3],
 136  link:RelNotes-1.5.6.2.txt[1.5.6.2],
 137  link:RelNotes-1.5.6.1.txt[1.5.6.1],
 138  link:RelNotes-1.5.6.txt[1.5.6].
 139
 140* link:v1.5.5.6/git.html[documentation for release 1.5.5.6]
 141
 142* release notes for
 143  link:RelNotes-1.5.5.6.txt[1.5.5.6],
 144  link:RelNotes-1.5.5.5.txt[1.5.5.5],
 145  link:RelNotes-1.5.5.4.txt[1.5.5.4],
 146  link:RelNotes-1.5.5.3.txt[1.5.5.3],
 147  link:RelNotes-1.5.5.2.txt[1.5.5.2],
 148  link:RelNotes-1.5.5.1.txt[1.5.5.1],
 149  link:RelNotes-1.5.5.txt[1.5.5].
 150
 151* link:v1.5.4.7/git.html[documentation for release 1.5.4.7]
 152
 153* release notes for
 154  link:RelNotes-1.5.4.7.txt[1.5.4.7],
 155  link:RelNotes-1.5.4.6.txt[1.5.4.6],
 156  link:RelNotes-1.5.4.5.txt[1.5.4.5],
 157  link:RelNotes-1.5.4.4.txt[1.5.4.4],
 158  link:RelNotes-1.5.4.3.txt[1.5.4.3],
 159  link:RelNotes-1.5.4.2.txt[1.5.4.2],
 160  link:RelNotes-1.5.4.1.txt[1.5.4.1],
 161  link:RelNotes-1.5.4.txt[1.5.4].
 162
 163* link:v1.5.3.8/git.html[documentation for release 1.5.3.8]
 164
 165* release notes for
 166  link:RelNotes-1.5.3.8.txt[1.5.3.8],
 167  link:RelNotes-1.5.3.7.txt[1.5.3.7],
 168  link:RelNotes-1.5.3.6.txt[1.5.3.6],
 169  link:RelNotes-1.5.3.5.txt[1.5.3.5],
 170  link:RelNotes-1.5.3.4.txt[1.5.3.4],
 171  link:RelNotes-1.5.3.3.txt[1.5.3.3],
 172  link:RelNotes-1.5.3.2.txt[1.5.3.2],
 173  link:RelNotes-1.5.3.1.txt[1.5.3.1],
 174  link:RelNotes-1.5.3.txt[1.5.3].
 175
 176* link:v1.5.2.5/git.html[documentation for release 1.5.2.5]
 177
 178* release notes for
 179  link:RelNotes-1.5.2.5.txt[1.5.2.5],
 180  link:RelNotes-1.5.2.4.txt[1.5.2.4],
 181  link:RelNotes-1.5.2.3.txt[1.5.2.3],
 182  link:RelNotes-1.5.2.2.txt[1.5.2.2],
 183  link:RelNotes-1.5.2.1.txt[1.5.2.1],
 184  link:RelNotes-1.5.2.txt[1.5.2].
 185
 186* link:v1.5.1.6/git.html[documentation for release 1.5.1.6]
 187
 188* release notes for
 189  link:RelNotes-1.5.1.6.txt[1.5.1.6],
 190  link:RelNotes-1.5.1.5.txt[1.5.1.5],
 191  link:RelNotes-1.5.1.4.txt[1.5.1.4],
 192  link:RelNotes-1.5.1.3.txt[1.5.1.3],
 193  link:RelNotes-1.5.1.2.txt[1.5.1.2],
 194  link:RelNotes-1.5.1.1.txt[1.5.1.1],
 195  link:RelNotes-1.5.1.txt[1.5.1].
 196
 197* link:v1.5.0.7/git.html[documentation for release 1.5.0.7]
 198
 199* release notes for
 200  link:RelNotes-1.5.0.7.txt[1.5.0.7],
 201  link:RelNotes-1.5.0.6.txt[1.5.0.6],
 202  link:RelNotes-1.5.0.5.txt[1.5.0.5],
 203  link:RelNotes-1.5.0.3.txt[1.5.0.3],
 204  link:RelNotes-1.5.0.2.txt[1.5.0.2],
 205  link:RelNotes-1.5.0.1.txt[1.5.0.1],
 206  link:RelNotes-1.5.0.txt[1.5.0].
 207
 208* documentation for release link:v1.4.4.4/git.html[1.4.4.4],
 209  link:v1.3.3/git.html[1.3.3],
 210  link:v1.2.6/git.html[1.2.6],
 211  link:v1.0.13/git.html[1.0.13].
 212
 213============
 214
 215endif::stalenotes[]
 216
 217OPTIONS
 218-------
 219--version::
 220        Prints the git suite version that the 'git' program came from.
 221
 222--help::
 223        Prints the synopsis and a list of the most commonly used
 224        commands. If the option '--all' or '-a' is given then all
 225        available commands are printed. If a git command is named this
 226        option will bring up the manual page for that command.
 227+
 228Other options are available to control how the manual page is
 229displayed. See linkgit:git-help[1] for more information,
 230because `git --help ...` is converted internally into `git
 231help ...`.
 232
 233-c <name>=<value>::
 234        Pass a configuration parameter to the command. The value
 235        given will override values from configuration files.
 236        The <name> is expected in the same format as listed by
 237        'git config' (subkeys separated by dots).
 238
 239--exec-path::
 240        Path to wherever your core git programs are installed.
 241        This can also be controlled by setting the GIT_EXEC_PATH
 242        environment variable. If no path is given, 'git' will print
 243        the current setting and then exit.
 244
 245--html-path::
 246        Print the path to wherever your git HTML documentation is installed
 247        and exit.
 248
 249-p::
 250--paginate::
 251        Pipe all output into 'less' (or if set, $PAGER) if standard
 252        output is a terminal.  This overrides the `pager.<cmd>`
 253        configuration options (see the "Configuration Mechanism" section
 254        below).
 255
 256--no-pager::
 257        Do not pipe git output into a pager.
 258
 259--git-dir=<path>::
 260        Set the path to the repository. This can also be controlled by
 261        setting the GIT_DIR environment variable. It can be an absolute
 262        path or relative path to current working directory.
 263
 264--work-tree=<path>::
 265        Set the path to the working tree.  The value will not be
 266        used in combination with repositories found automatically in
 267        a .git directory (i.e. $GIT_DIR is not set).
 268        This can also be controlled by setting the GIT_WORK_TREE
 269        environment variable and the core.worktree configuration
 270        variable. It can be an absolute path or relative path to
 271        the directory specified by --git-dir or GIT_DIR.
 272        Note: If --git-dir or GIT_DIR are specified but none of
 273        --work-tree, GIT_WORK_TREE and core.worktree is specified,
 274        the current working directory is regarded as the top directory
 275        of your working tree.
 276
 277--bare::
 278        Treat the repository as a bare repository.  If GIT_DIR
 279        environment is not set, it is set to the current working
 280        directory.
 281
 282--no-replace-objects::
 283        Do not use replacement refs to replace git objects. See
 284        linkgit:git-replace[1] for more information.
 285
 286
 287FURTHER DOCUMENTATION
 288---------------------
 289
 290See the references above to get started using git.  The following is
 291probably more detail than necessary for a first-time user.
 292
 293The link:user-manual.html#git-concepts[git concepts chapter of the
 294user-manual] and linkgit:gitcore-tutorial[7] both provide
 295introductions to the underlying git architecture.
 296
 297See linkgit:gitworkflows[7] for an overview of recommended workflows.
 298
 299See also the link:howto-index.html[howto] documents for some useful
 300examples.
 301
 302The internals are documented in the
 303link:technical/api-index.html[GIT API documentation].
 304
 305GIT COMMANDS
 306------------
 307
 308We divide git into high level ("porcelain") commands and low level
 309("plumbing") commands.
 310
 311High-level commands (porcelain)
 312-------------------------------
 313
 314We separate the porcelain commands into the main commands and some
 315ancillary user utilities.
 316
 317Main porcelain commands
 318~~~~~~~~~~~~~~~~~~~~~~~
 319
 320include::cmds-mainporcelain.txt[]
 321
 322Ancillary Commands
 323~~~~~~~~~~~~~~~~~~
 324Manipulators:
 325
 326include::cmds-ancillarymanipulators.txt[]
 327
 328Interrogators:
 329
 330include::cmds-ancillaryinterrogators.txt[]
 331
 332
 333Interacting with Others
 334~~~~~~~~~~~~~~~~~~~~~~~
 335
 336These commands are to interact with foreign SCM and with other
 337people via patch over e-mail.
 338
 339include::cmds-foreignscminterface.txt[]
 340
 341
 342Low-level commands (plumbing)
 343-----------------------------
 344
 345Although git includes its
 346own porcelain layer, its low-level commands are sufficient to support
 347development of alternative porcelains.  Developers of such porcelains
 348might start by reading about linkgit:git-update-index[1] and
 349linkgit:git-read-tree[1].
 350
 351The interface (input, output, set of options and the semantics)
 352to these low-level commands are meant to be a lot more stable
 353than Porcelain level commands, because these commands are
 354primarily for scripted use.  The interface to Porcelain commands
 355on the other hand are subject to change in order to improve the
 356end user experience.
 357
 358The following description divides
 359the low-level commands into commands that manipulate objects (in
 360the repository, index, and working tree), commands that interrogate and
 361compare objects, and commands that move objects and references between
 362repositories.
 363
 364
 365Manipulation commands
 366~~~~~~~~~~~~~~~~~~~~~
 367
 368include::cmds-plumbingmanipulators.txt[]
 369
 370
 371Interrogation commands
 372~~~~~~~~~~~~~~~~~~~~~~
 373
 374include::cmds-plumbinginterrogators.txt[]
 375
 376In general, the interrogate commands do not touch the files in
 377the working tree.
 378
 379
 380Synching repositories
 381~~~~~~~~~~~~~~~~~~~~~
 382
 383include::cmds-synchingrepositories.txt[]
 384
 385The following are helper commands used by the above; end users
 386typically do not use them directly.
 387
 388include::cmds-synchelpers.txt[]
 389
 390
 391Internal helper commands
 392~~~~~~~~~~~~~~~~~~~~~~~~
 393
 394These are internal helper commands used by other commands; end
 395users typically do not use them directly.
 396
 397include::cmds-purehelpers.txt[]
 398
 399
 400Configuration Mechanism
 401-----------------------
 402
 403Starting from 0.99.9 (actually mid 0.99.8.GIT), `.git/config` file
 404is used to hold per-repository configuration options.  It is a
 405simple text file modeled after `.ini` format familiar to some
 406people.  Here is an example:
 407
 408------------
 409#
 410# A '#' or ';' character indicates a comment.
 411#
 412
 413; core variables
 414[core]
 415        ; Don't trust file modes
 416        filemode = false
 417
 418; user identity
 419[user]
 420        name = "Junio C Hamano"
 421        email = "junkio@twinsun.com"
 422
 423------------
 424
 425Various commands read from the configuration file and adjust
 426their operation accordingly.  See linkgit:git-config[1] for a
 427list.
 428
 429
 430Identifier Terminology
 431----------------------
 432<object>::
 433        Indicates the object name for any type of object.
 434
 435<blob>::
 436        Indicates a blob object name.
 437
 438<tree>::
 439        Indicates a tree object name.
 440
 441<commit>::
 442        Indicates a commit object name.
 443
 444<tree-ish>::
 445        Indicates a tree, commit or tag object name.  A
 446        command that takes a <tree-ish> argument ultimately wants to
 447        operate on a <tree> object but automatically dereferences
 448        <commit> and <tag> objects that point at a <tree>.
 449
 450<commit-ish>::
 451        Indicates a commit or tag object name.  A
 452        command that takes a <commit-ish> argument ultimately wants to
 453        operate on a <commit> object but automatically dereferences
 454        <tag> objects that point at a <commit>.
 455
 456<type>::
 457        Indicates that an object type is required.
 458        Currently one of: `blob`, `tree`, `commit`, or `tag`.
 459
 460<file>::
 461        Indicates a filename - almost always relative to the
 462        root of the tree structure `GIT_INDEX_FILE` describes.
 463
 464Symbolic Identifiers
 465--------------------
 466Any git command accepting any <object> can also use the following
 467symbolic notation:
 468
 469HEAD::
 470        indicates the head of the current branch (i.e. the
 471        contents of `$GIT_DIR/HEAD`).
 472
 473<tag>::
 474        a valid tag 'name'
 475        (i.e. the contents of `$GIT_DIR/refs/tags/<tag>`).
 476
 477<head>::
 478        a valid head 'name'
 479        (i.e. the contents of `$GIT_DIR/refs/heads/<head>`).
 480
 481For a more complete list of ways to spell object names, see
 482"SPECIFYING REVISIONS" section in linkgit:gitrevisions[1].
 483
 484
 485File/Directory Structure
 486------------------------
 487
 488Please see the linkgit:gitrepository-layout[5] document.
 489
 490Read linkgit:githooks[5] for more details about each hook.
 491
 492Higher level SCMs may provide and manage additional information in the
 493`$GIT_DIR`.
 494
 495
 496Terminology
 497-----------
 498Please see linkgit:gitglossary[7].
 499
 500
 501Environment Variables
 502---------------------
 503Various git commands use the following environment variables:
 504
 505The git Repository
 506~~~~~~~~~~~~~~~~~~
 507These environment variables apply to 'all' core git commands. Nb: it
 508is worth noting that they may be used/overridden by SCMS sitting above
 509git so take care if using Cogito etc.
 510
 511'GIT_INDEX_FILE'::
 512        This environment allows the specification of an alternate
 513        index file. If not specified, the default of `$GIT_DIR/index`
 514        is used.
 515
 516'GIT_OBJECT_DIRECTORY'::
 517        If the object storage directory is specified via this
 518        environment variable then the sha1 directories are created
 519        underneath - otherwise the default `$GIT_DIR/objects`
 520        directory is used.
 521
 522'GIT_ALTERNATE_OBJECT_DIRECTORIES'::
 523        Due to the immutable nature of git objects, old objects can be
 524        archived into shared, read-only directories. This variable
 525        specifies a ":" separated (on Windows ";" separated) list
 526        of git object directories which can be used to search for git
 527        objects. New objects will not be written to these directories.
 528
 529'GIT_DIR'::
 530        If the 'GIT_DIR' environment variable is set then it
 531        specifies a path to use instead of the default `.git`
 532        for the base of the repository.
 533
 534'GIT_WORK_TREE'::
 535        Set the path to the working tree.  The value will not be
 536        used in combination with repositories found automatically in
 537        a .git directory (i.e. $GIT_DIR is not set).
 538        This can also be controlled by the '--work-tree' command line
 539        option and the core.worktree configuration variable.
 540
 541'GIT_CEILING_DIRECTORIES'::
 542        This should be a colon-separated list of absolute paths.
 543        If set, it is a list of directories that git should not chdir
 544        up into while looking for a repository directory.
 545        It will not exclude the current working directory or
 546        a GIT_DIR set on the command line or in the environment.
 547        (Useful for excluding slow-loading network directories.)
 548
 549'GIT_DISCOVERY_ACROSS_FILESYSTEM'::
 550        When run in a directory that does not have ".git" repository
 551        directory, git tries to find such a directory in the parent
 552        directories to find the top of the working tree, but by default it
 553        does not cross filesystem boundaries.  This environment variable
 554        can be set to true to tell git not to stop at filesystem
 555        boundaries.  Like 'GIT_CEILING_DIRECTORIES', this will not affect
 556        an explicit repository directory set via 'GIT_DIR' or on the
 557        command line.
 558
 559git Commits
 560~~~~~~~~~~~
 561'GIT_AUTHOR_NAME'::
 562'GIT_AUTHOR_EMAIL'::
 563'GIT_AUTHOR_DATE'::
 564'GIT_COMMITTER_NAME'::
 565'GIT_COMMITTER_EMAIL'::
 566'GIT_COMMITTER_DATE'::
 567'EMAIL'::
 568        see linkgit:git-commit-tree[1]
 569
 570git Diffs
 571~~~~~~~~~
 572'GIT_DIFF_OPTS'::
 573        Only valid setting is "--unified=??" or "-u??" to set the
 574        number of context lines shown when a unified diff is created.
 575        This takes precedence over any "-U" or "--unified" option
 576        value passed on the git diff command line.
 577
 578'GIT_EXTERNAL_DIFF'::
 579        When the environment variable 'GIT_EXTERNAL_DIFF' is set, the
 580        program named by it is called, instead of the diff invocation
 581        described above.  For a path that is added, removed, or modified,
 582        'GIT_EXTERNAL_DIFF' is called with 7 parameters:
 583
 584        path old-file old-hex old-mode new-file new-hex new-mode
 585+
 586where:
 587
 588        <old|new>-file:: are files GIT_EXTERNAL_DIFF can use to read the
 589                         contents of <old|new>,
 590        <old|new>-hex:: are the 40-hexdigit SHA1 hashes,
 591        <old|new>-mode:: are the octal representation of the file modes.
 592
 593+
 594The file parameters can point at the user's working file
 595(e.g. `new-file` in "git-diff-files"), `/dev/null` (e.g. `old-file`
 596when a new file is added), or a temporary file (e.g. `old-file` in the
 597index).  'GIT_EXTERNAL_DIFF' should not worry about unlinking the
 598temporary file --- it is removed when 'GIT_EXTERNAL_DIFF' exits.
 599+
 600For a path that is unmerged, 'GIT_EXTERNAL_DIFF' is called with 1
 601parameter, <path>.
 602
 603other
 604~~~~~
 605'GIT_MERGE_VERBOSITY'::
 606        A number controlling the amount of output shown by
 607        the recursive merge strategy.  Overrides merge.verbosity.
 608        See linkgit:git-merge[1]
 609
 610'GIT_PAGER'::
 611        This environment variable overrides `$PAGER`. If it is set
 612        to an empty string or to the value "cat", git will not launch
 613        a pager.  See also the `core.pager` option in
 614        linkgit:git-config[1].
 615
 616'GIT_SSH'::
 617        If this environment variable is set then 'git fetch'
 618        and 'git push' will use this command instead
 619        of 'ssh' when they need to connect to a remote system.
 620        The '$GIT_SSH' command will be given exactly two arguments:
 621        the 'username@host' (or just 'host') from the URL and the
 622        shell command to execute on that remote system.
 623+
 624To pass options to the program that you want to list in GIT_SSH
 625you will need to wrap the program and options into a shell script,
 626then set GIT_SSH to refer to the shell script.
 627+
 628Usually it is easier to configure any desired options through your
 629personal `.ssh/config` file.  Please consult your ssh documentation
 630for further details.
 631
 632'GIT_FLUSH'::
 633        If this environment variable is set to "1", then commands such
 634        as 'git blame' (in incremental mode), 'git rev-list', 'git log',
 635        and 'git whatchanged' will force a flush of the output stream
 636        after each commit-oriented record have been flushed.   If this
 637        variable is set to "0", the output of these commands will be done
 638        using completely buffered I/O.   If this environment variable is
 639        not set, git will choose buffered or record-oriented flushing
 640        based on whether stdout appears to be redirected to a file or not.
 641
 642'GIT_TRACE'::
 643        If this variable is set to "1", "2" or "true" (comparison
 644        is case insensitive), git will print `trace:` messages on
 645        stderr telling about alias expansion, built-in command
 646        execution and external command execution.
 647        If this variable is set to an integer value greater than 1
 648        and lower than 10 (strictly) then git will interpret this
 649        value as an open file descriptor and will try to write the
 650        trace messages into this file descriptor.
 651        Alternatively, if this variable is set to an absolute path
 652        (starting with a '/' character), git will interpret this
 653        as a file path and will try to write the trace messages
 654        into it.
 655
 656Discussion[[Discussion]]
 657------------------------
 658
 659More detail on the following is available from the
 660link:user-manual.html#git-concepts[git concepts chapter of the
 661user-manual] and linkgit:gitcore-tutorial[7].
 662
 663A git project normally consists of a working directory with a ".git"
 664subdirectory at the top level.  The .git directory contains, among other
 665things, a compressed object database representing the complete history
 666of the project, an "index" file which links that history to the current
 667contents of the working tree, and named pointers into that history such
 668as tags and branch heads.
 669
 670The object database contains objects of three main types: blobs, which
 671hold file data; trees, which point to blobs and other trees to build up
 672directory hierarchies; and commits, which each reference a single tree
 673and some number of parent commits.
 674
 675The commit, equivalent to what other systems call a "changeset" or
 676"version", represents a step in the project's history, and each parent
 677represents an immediately preceding step.  Commits with more than one
 678parent represent merges of independent lines of development.
 679
 680All objects are named by the SHA1 hash of their contents, normally
 681written as a string of 40 hex digits.  Such names are globally unique.
 682The entire history leading up to a commit can be vouched for by signing
 683just that commit.  A fourth object type, the tag, is provided for this
 684purpose.
 685
 686When first created, objects are stored in individual files, but for
 687efficiency may later be compressed together into "pack files".
 688
 689Named pointers called refs mark interesting points in history.  A ref
 690may contain the SHA1 name of an object or the name of another ref.  Refs
 691with names beginning `ref/head/` contain the SHA1 name of the most
 692recent commit (or "head") of a branch under development.  SHA1 names of
 693tags of interest are stored under `ref/tags/`.  A special ref named
 694`HEAD` contains the name of the currently checked-out branch.
 695
 696The index file is initialized with a list of all paths and, for each
 697path, a blob object and a set of attributes.  The blob object represents
 698the contents of the file as of the head of the current branch.  The
 699attributes (last modified time, size, etc.) are taken from the
 700corresponding file in the working tree.  Subsequent changes to the
 701working tree can be found by comparing these attributes.  The index may
 702be updated with new content, and new commits may be created from the
 703content stored in the index.
 704
 705The index is also capable of storing multiple entries (called "stages")
 706for a given pathname.  These stages are used to hold the various
 707unmerged version of a file when a merge is in progress.
 708
 709Authors
 710-------
 711* git's founding father is Linus Torvalds <torvalds@osdl.org>.
 712* The current git nurse is Junio C Hamano <gitster@pobox.com>.
 713* The git potty was written by Andreas Ericsson <ae@op5.se>.
 714* General upbringing is handled by the git-list <git@vger.kernel.org>.
 715
 716Documentation
 717--------------
 718The documentation for git suite was started by David Greaves
 719<david@dgreaves.com>, and later enhanced greatly by the
 720contributors on the git-list <git@vger.kernel.org>.
 721
 722SEE ALSO
 723--------
 724linkgit:gittutorial[7], linkgit:gittutorial-2[7],
 725link:everyday.html[Everyday Git], linkgit:gitcvs-migration[7],
 726linkgit:gitglossary[7], linkgit:gitcore-tutorial[7],
 727linkgit:gitcli[7], link:user-manual.html[The Git User's Manual],
 728linkgit:gitworkflows[7]
 729
 730GIT
 731---
 732Part of the linkgit:git[1] suite