Documentation / git.txton commit Better advice on using topic branches for kernel development (352953a)
   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:v1.7.3.1/git.html[documentation for release 1.7.3.1]
  48
  49* release notes for
  50  link:RelNotes/1.7.3.1.txt[1.7.3.1],
  51  link:RelNotes/1.7.3.txt[1.7.3].
  52
  53* link:v1.7.2.3/git.html[documentation for release 1.7.2.3]
  54
  55* release notes for
  56  link:RelNotes/1.7.2.3.txt[1.7.2.3],
  57  link:RelNotes/1.7.2.2.txt[1.7.2.2],
  58  link:RelNotes/1.7.2.1.txt[1.7.2.1],
  59  link:RelNotes/1.7.2.txt[1.7.2].
  60
  61* link:v1.7.1.2/git.html[documentation for release 1.7.1.2]
  62
  63* release notes for
  64  link:RelNotes/1.7.1.2.txt[1.7.1.2],
  65  link:RelNotes/1.7.1.1.txt[1.7.1.1],
  66  link:RelNotes/1.7.1.txt[1.7.1].
  67
  68* link:v1.7.0.7/git.html[documentation for release 1.7.0.7]
  69
  70* release notes for
  71  link:RelNotes/1.7.0.7.txt[1.7.0.7],
  72  link:RelNotes/1.7.0.6.txt[1.7.0.6],
  73  link:RelNotes/1.7.0.5.txt[1.7.0.5],
  74  link:RelNotes/1.7.0.4.txt[1.7.0.4],
  75  link:RelNotes/1.7.0.3.txt[1.7.0.3],
  76  link:RelNotes/1.7.0.2.txt[1.7.0.2],
  77  link:RelNotes/1.7.0.1.txt[1.7.0.1],
  78  link:RelNotes/1.7.0.txt[1.7.0].
  79
  80* link:v1.6.6.2/git.html[documentation for release 1.6.6.2]
  81
  82* release notes for
  83  link:RelNotes/1.6.6.2.txt[1.6.6.2],
  84  link:RelNotes/1.6.6.1.txt[1.6.6.1],
  85  link:RelNotes/1.6.6.txt[1.6.6].
  86
  87* link:v1.6.5.8/git.html[documentation for release 1.6.5.8]
  88
  89* release notes for
  90  link:RelNotes/1.6.5.8.txt[1.6.5.8],
  91  link:RelNotes/1.6.5.7.txt[1.6.5.7],
  92  link:RelNotes/1.6.5.6.txt[1.6.5.6],
  93  link:RelNotes/1.6.5.5.txt[1.6.5.5],
  94  link:RelNotes/1.6.5.4.txt[1.6.5.4],
  95  link:RelNotes/1.6.5.3.txt[1.6.5.3],
  96  link:RelNotes/1.6.5.2.txt[1.6.5.2],
  97  link:RelNotes/1.6.5.1.txt[1.6.5.1],
  98  link:RelNotes/1.6.5.txt[1.6.5].
  99
 100* link:v1.6.4.4/git.html[documentation for release 1.6.4.4]
 101
 102* release notes for
 103  link:RelNotes/1.6.4.4.txt[1.6.4.4],
 104  link:RelNotes/1.6.4.3.txt[1.6.4.3],
 105  link:RelNotes/1.6.4.2.txt[1.6.4.2],
 106  link:RelNotes/1.6.4.1.txt[1.6.4.1],
 107  link:RelNotes/1.6.4.txt[1.6.4].
 108
 109* link:v1.6.3.4/git.html[documentation for release 1.6.3.4]
 110
 111* release notes for
 112  link:RelNotes/1.6.3.4.txt[1.6.3.4],
 113  link:RelNotes/1.6.3.3.txt[1.6.3.3],
 114  link:RelNotes/1.6.3.2.txt[1.6.3.2],
 115  link:RelNotes/1.6.3.1.txt[1.6.3.1],
 116  link:RelNotes/1.6.3.txt[1.6.3].
 117
 118* release notes for
 119  link:RelNotes/1.6.2.5.txt[1.6.2.5],
 120  link:RelNotes/1.6.2.4.txt[1.6.2.4],
 121  link:RelNotes/1.6.2.3.txt[1.6.2.3],
 122  link:RelNotes/1.6.2.2.txt[1.6.2.2],
 123  link:RelNotes/1.6.2.1.txt[1.6.2.1],
 124  link:RelNotes/1.6.2.txt[1.6.2].
 125
 126* link:v1.6.1.3/git.html[documentation for release 1.6.1.3]
 127
 128* release notes for
 129  link:RelNotes/1.6.1.3.txt[1.6.1.3],
 130  link:RelNotes/1.6.1.2.txt[1.6.1.2],
 131  link:RelNotes/1.6.1.1.txt[1.6.1.1],
 132  link:RelNotes/1.6.1.txt[1.6.1].
 133
 134* link:v1.6.0.6/git.html[documentation for release 1.6.0.6]
 135
 136* release notes for
 137  link:RelNotes/1.6.0.6.txt[1.6.0.6],
 138  link:RelNotes/1.6.0.5.txt[1.6.0.5],
 139  link:RelNotes/1.6.0.4.txt[1.6.0.4],
 140  link:RelNotes/1.6.0.3.txt[1.6.0.3],
 141  link:RelNotes/1.6.0.2.txt[1.6.0.2],
 142  link:RelNotes/1.6.0.1.txt[1.6.0.1],
 143  link:RelNotes/1.6.0.txt[1.6.0].
 144
 145* link:v1.5.6.6/git.html[documentation for release 1.5.6.6]
 146
 147* release notes for
 148  link:RelNotes/1.5.6.6.txt[1.5.6.6],
 149  link:RelNotes/1.5.6.5.txt[1.5.6.5],
 150  link:RelNotes/1.5.6.4.txt[1.5.6.4],
 151  link:RelNotes/1.5.6.3.txt[1.5.6.3],
 152  link:RelNotes/1.5.6.2.txt[1.5.6.2],
 153  link:RelNotes/1.5.6.1.txt[1.5.6.1],
 154  link:RelNotes/1.5.6.txt[1.5.6].
 155
 156* link:v1.5.5.6/git.html[documentation for release 1.5.5.6]
 157
 158* release notes for
 159  link:RelNotes/1.5.5.6.txt[1.5.5.6],
 160  link:RelNotes/1.5.5.5.txt[1.5.5.5],
 161  link:RelNotes/1.5.5.4.txt[1.5.5.4],
 162  link:RelNotes/1.5.5.3.txt[1.5.5.3],
 163  link:RelNotes/1.5.5.2.txt[1.5.5.2],
 164  link:RelNotes/1.5.5.1.txt[1.5.5.1],
 165  link:RelNotes/1.5.5.txt[1.5.5].
 166
 167* link:v1.5.4.7/git.html[documentation for release 1.5.4.7]
 168
 169* release notes for
 170  link:RelNotes/1.5.4.7.txt[1.5.4.7],
 171  link:RelNotes/1.5.4.6.txt[1.5.4.6],
 172  link:RelNotes/1.5.4.5.txt[1.5.4.5],
 173  link:RelNotes/1.5.4.4.txt[1.5.4.4],
 174  link:RelNotes/1.5.4.3.txt[1.5.4.3],
 175  link:RelNotes/1.5.4.2.txt[1.5.4.2],
 176  link:RelNotes/1.5.4.1.txt[1.5.4.1],
 177  link:RelNotes/1.5.4.txt[1.5.4].
 178
 179* link:v1.5.3.8/git.html[documentation for release 1.5.3.8]
 180
 181* release notes for
 182  link:RelNotes/1.5.3.8.txt[1.5.3.8],
 183  link:RelNotes/1.5.3.7.txt[1.5.3.7],
 184  link:RelNotes/1.5.3.6.txt[1.5.3.6],
 185  link:RelNotes/1.5.3.5.txt[1.5.3.5],
 186  link:RelNotes/1.5.3.4.txt[1.5.3.4],
 187  link:RelNotes/1.5.3.3.txt[1.5.3.3],
 188  link:RelNotes/1.5.3.2.txt[1.5.3.2],
 189  link:RelNotes/1.5.3.1.txt[1.5.3.1],
 190  link:RelNotes/1.5.3.txt[1.5.3].
 191
 192* link:v1.5.2.5/git.html[documentation for release 1.5.2.5]
 193
 194* release notes for
 195  link:RelNotes/1.5.2.5.txt[1.5.2.5],
 196  link:RelNotes/1.5.2.4.txt[1.5.2.4],
 197  link:RelNotes/1.5.2.3.txt[1.5.2.3],
 198  link:RelNotes/1.5.2.2.txt[1.5.2.2],
 199  link:RelNotes/1.5.2.1.txt[1.5.2.1],
 200  link:RelNotes/1.5.2.txt[1.5.2].
 201
 202* link:v1.5.1.6/git.html[documentation for release 1.5.1.6]
 203
 204* release notes for
 205  link:RelNotes/1.5.1.6.txt[1.5.1.6],
 206  link:RelNotes/1.5.1.5.txt[1.5.1.5],
 207  link:RelNotes/1.5.1.4.txt[1.5.1.4],
 208  link:RelNotes/1.5.1.3.txt[1.5.1.3],
 209  link:RelNotes/1.5.1.2.txt[1.5.1.2],
 210  link:RelNotes/1.5.1.1.txt[1.5.1.1],
 211  link:RelNotes/1.5.1.txt[1.5.1].
 212
 213* link:v1.5.0.7/git.html[documentation for release 1.5.0.7]
 214
 215* release notes for
 216  link:RelNotes/1.5.0.7.txt[1.5.0.7],
 217  link:RelNotes/1.5.0.6.txt[1.5.0.6],
 218  link:RelNotes/1.5.0.5.txt[1.5.0.5],
 219  link:RelNotes/1.5.0.3.txt[1.5.0.3],
 220  link:RelNotes/1.5.0.2.txt[1.5.0.2],
 221  link:RelNotes/1.5.0.1.txt[1.5.0.1],
 222  link:RelNotes/1.5.0.txt[1.5.0].
 223
 224* documentation for release link:v1.4.4.4/git.html[1.4.4.4],
 225  link:v1.3.3/git.html[1.3.3],
 226  link:v1.2.6/git.html[1.2.6],
 227  link:v1.0.13/git.html[1.0.13].
 228
 229============
 230
 231endif::stalenotes[]
 232
 233OPTIONS
 234-------
 235--version::
 236        Prints the git suite version that the 'git' program came from.
 237
 238--help::
 239        Prints the synopsis and a list of the most commonly used
 240        commands. If the option '--all' or '-a' is given then all
 241        available commands are printed. If a git command is named this
 242        option will bring up the manual page for that command.
 243+
 244Other options are available to control how the manual page is
 245displayed. See linkgit:git-help[1] for more information,
 246because `git --help ...` is converted internally into `git
 247help ...`.
 248
 249-c <name>=<value>::
 250        Pass a configuration parameter to the command. The value
 251        given will override values from configuration files.
 252        The <name> is expected in the same format as listed by
 253        'git config' (subkeys separated by dots).
 254
 255--exec-path::
 256        Path to wherever your core git programs are installed.
 257        This can also be controlled by setting the GIT_EXEC_PATH
 258        environment variable. If no path is given, 'git' will print
 259        the current setting and then exit.
 260
 261--html-path::
 262        Print the path to wherever your git HTML documentation is installed
 263        and exit.
 264
 265-p::
 266--paginate::
 267        Pipe all output into 'less' (or if set, $PAGER) if standard
 268        output is a terminal.  This overrides the `pager.<cmd>`
 269        configuration options (see the "Configuration Mechanism" section
 270        below).
 271
 272--no-pager::
 273        Do not pipe git output into a pager.
 274
 275--git-dir=<path>::
 276        Set the path to the repository. This can also be controlled by
 277        setting the GIT_DIR environment variable. It can be an absolute
 278        path or relative path to current working directory.
 279
 280--work-tree=<path>::
 281        Set the path to the working tree.  The value will not be
 282        used in combination with repositories found automatically in
 283        a .git directory (i.e. $GIT_DIR is not set).
 284        This can also be controlled by setting the GIT_WORK_TREE
 285        environment variable and the core.worktree configuration
 286        variable. It can be an absolute path or relative path to
 287        the directory specified by --git-dir or GIT_DIR.
 288        Note: If --git-dir or GIT_DIR are specified but none of
 289        --work-tree, GIT_WORK_TREE and core.worktree is specified,
 290        the current working directory is regarded as the top directory
 291        of your working tree.
 292
 293--bare::
 294        Treat the repository as a bare repository.  If GIT_DIR
 295        environment is not set, it is set to the current working
 296        directory.
 297
 298--no-replace-objects::
 299        Do not use replacement refs to replace git objects. See
 300        linkgit:git-replace[1] for more information.
 301
 302
 303FURTHER DOCUMENTATION
 304---------------------
 305
 306See the references above to get started using git.  The following is
 307probably more detail than necessary for a first-time user.
 308
 309The link:user-manual.html#git-concepts[git concepts chapter of the
 310user-manual] and linkgit:gitcore-tutorial[7] both provide
 311introductions to the underlying git architecture.
 312
 313See linkgit:gitworkflows[7] for an overview of recommended workflows.
 314
 315See also the link:howto-index.html[howto] documents for some useful
 316examples.
 317
 318The internals are documented in the
 319link:technical/api-index.html[GIT API documentation].
 320
 321GIT COMMANDS
 322------------
 323
 324We divide git into high level ("porcelain") commands and low level
 325("plumbing") commands.
 326
 327High-level commands (porcelain)
 328-------------------------------
 329
 330We separate the porcelain commands into the main commands and some
 331ancillary user utilities.
 332
 333Main porcelain commands
 334~~~~~~~~~~~~~~~~~~~~~~~
 335
 336include::cmds-mainporcelain.txt[]
 337
 338Ancillary Commands
 339~~~~~~~~~~~~~~~~~~
 340Manipulators:
 341
 342include::cmds-ancillarymanipulators.txt[]
 343
 344Interrogators:
 345
 346include::cmds-ancillaryinterrogators.txt[]
 347
 348
 349Interacting with Others
 350~~~~~~~~~~~~~~~~~~~~~~~
 351
 352These commands are to interact with foreign SCM and with other
 353people via patch over e-mail.
 354
 355include::cmds-foreignscminterface.txt[]
 356
 357
 358Low-level commands (plumbing)
 359-----------------------------
 360
 361Although git includes its
 362own porcelain layer, its low-level commands are sufficient to support
 363development of alternative porcelains.  Developers of such porcelains
 364might start by reading about linkgit:git-update-index[1] and
 365linkgit:git-read-tree[1].
 366
 367The interface (input, output, set of options and the semantics)
 368to these low-level commands are meant to be a lot more stable
 369than Porcelain level commands, because these commands are
 370primarily for scripted use.  The interface to Porcelain commands
 371on the other hand are subject to change in order to improve the
 372end user experience.
 373
 374The following description divides
 375the low-level commands into commands that manipulate objects (in
 376the repository, index, and working tree), commands that interrogate and
 377compare objects, and commands that move objects and references between
 378repositories.
 379
 380
 381Manipulation commands
 382~~~~~~~~~~~~~~~~~~~~~
 383
 384include::cmds-plumbingmanipulators.txt[]
 385
 386
 387Interrogation commands
 388~~~~~~~~~~~~~~~~~~~~~~
 389
 390include::cmds-plumbinginterrogators.txt[]
 391
 392In general, the interrogate commands do not touch the files in
 393the working tree.
 394
 395
 396Synching repositories
 397~~~~~~~~~~~~~~~~~~~~~
 398
 399include::cmds-synchingrepositories.txt[]
 400
 401The following are helper commands used by the above; end users
 402typically do not use them directly.
 403
 404include::cmds-synchelpers.txt[]
 405
 406
 407Internal helper commands
 408~~~~~~~~~~~~~~~~~~~~~~~~
 409
 410These are internal helper commands used by other commands; end
 411users typically do not use them directly.
 412
 413include::cmds-purehelpers.txt[]
 414
 415
 416Configuration Mechanism
 417-----------------------
 418
 419Starting from 0.99.9 (actually mid 0.99.8.GIT), `.git/config` file
 420is used to hold per-repository configuration options.  It is a
 421simple text file modeled after `.ini` format familiar to some
 422people.  Here is an example:
 423
 424------------
 425#
 426# A '#' or ';' character indicates a comment.
 427#
 428
 429; core variables
 430[core]
 431        ; Don't trust file modes
 432        filemode = false
 433
 434; user identity
 435[user]
 436        name = "Junio C Hamano"
 437        email = "junkio@twinsun.com"
 438
 439------------
 440
 441Various commands read from the configuration file and adjust
 442their operation accordingly.  See linkgit:git-config[1] for a
 443list.
 444
 445
 446Identifier Terminology
 447----------------------
 448<object>::
 449        Indicates the object name for any type of object.
 450
 451<blob>::
 452        Indicates a blob object name.
 453
 454<tree>::
 455        Indicates a tree object name.
 456
 457<commit>::
 458        Indicates a commit object name.
 459
 460<tree-ish>::
 461        Indicates a tree, commit or tag object name.  A
 462        command that takes a <tree-ish> argument ultimately wants to
 463        operate on a <tree> object but automatically dereferences
 464        <commit> and <tag> objects that point at a <tree>.
 465
 466<commit-ish>::
 467        Indicates a commit or tag object name.  A
 468        command that takes a <commit-ish> argument ultimately wants to
 469        operate on a <commit> object but automatically dereferences
 470        <tag> objects that point at a <commit>.
 471
 472<type>::
 473        Indicates that an object type is required.
 474        Currently one of: `blob`, `tree`, `commit`, or `tag`.
 475
 476<file>::
 477        Indicates a filename - almost always relative to the
 478        root of the tree structure `GIT_INDEX_FILE` describes.
 479
 480Symbolic Identifiers
 481--------------------
 482Any git command accepting any <object> can also use the following
 483symbolic notation:
 484
 485HEAD::
 486        indicates the head of the current branch (i.e. the
 487        contents of `$GIT_DIR/HEAD`).
 488
 489<tag>::
 490        a valid tag 'name'
 491        (i.e. the contents of `$GIT_DIR/refs/tags/<tag>`).
 492
 493<head>::
 494        a valid head 'name'
 495        (i.e. the contents of `$GIT_DIR/refs/heads/<head>`).
 496
 497For a more complete list of ways to spell object names, see
 498"SPECIFYING REVISIONS" section in linkgit:gitrevisions[7].
 499
 500
 501File/Directory Structure
 502------------------------
 503
 504Please see the linkgit:gitrepository-layout[5] document.
 505
 506Read linkgit:githooks[5] for more details about each hook.
 507
 508Higher level SCMs may provide and manage additional information in the
 509`$GIT_DIR`.
 510
 511
 512Terminology
 513-----------
 514Please see linkgit:gitglossary[7].
 515
 516
 517Environment Variables
 518---------------------
 519Various git commands use the following environment variables:
 520
 521The git Repository
 522~~~~~~~~~~~~~~~~~~
 523These environment variables apply to 'all' core git commands. Nb: it
 524is worth noting that they may be used/overridden by SCMS sitting above
 525git so take care if using Cogito etc.
 526
 527'GIT_INDEX_FILE'::
 528        This environment allows the specification of an alternate
 529        index file. If not specified, the default of `$GIT_DIR/index`
 530        is used.
 531
 532'GIT_OBJECT_DIRECTORY'::
 533        If the object storage directory is specified via this
 534        environment variable then the sha1 directories are created
 535        underneath - otherwise the default `$GIT_DIR/objects`
 536        directory is used.
 537
 538'GIT_ALTERNATE_OBJECT_DIRECTORIES'::
 539        Due to the immutable nature of git objects, old objects can be
 540        archived into shared, read-only directories. This variable
 541        specifies a ":" separated (on Windows ";" separated) list
 542        of git object directories which can be used to search for git
 543        objects. New objects will not be written to these directories.
 544
 545'GIT_DIR'::
 546        If the 'GIT_DIR' environment variable is set then it
 547        specifies a path to use instead of the default `.git`
 548        for the base of the repository.
 549
 550'GIT_WORK_TREE'::
 551        Set the path to the working tree.  The value will not be
 552        used in combination with repositories found automatically in
 553        a .git directory (i.e. $GIT_DIR is not set).
 554        This can also be controlled by the '--work-tree' command line
 555        option and the core.worktree configuration variable.
 556
 557'GIT_CEILING_DIRECTORIES'::
 558        This should be a colon-separated list of absolute paths.
 559        If set, it is a list of directories that git should not chdir
 560        up into while looking for a repository directory.
 561        It will not exclude the current working directory or
 562        a GIT_DIR set on the command line or in the environment.
 563        (Useful for excluding slow-loading network directories.)
 564
 565'GIT_DISCOVERY_ACROSS_FILESYSTEM'::
 566        When run in a directory that does not have ".git" repository
 567        directory, git tries to find such a directory in the parent
 568        directories to find the top of the working tree, but by default it
 569        does not cross filesystem boundaries.  This environment variable
 570        can be set to true to tell git not to stop at filesystem
 571        boundaries.  Like 'GIT_CEILING_DIRECTORIES', this will not affect
 572        an explicit repository directory set via 'GIT_DIR' or on the
 573        command line.
 574
 575git Commits
 576~~~~~~~~~~~
 577'GIT_AUTHOR_NAME'::
 578'GIT_AUTHOR_EMAIL'::
 579'GIT_AUTHOR_DATE'::
 580'GIT_COMMITTER_NAME'::
 581'GIT_COMMITTER_EMAIL'::
 582'GIT_COMMITTER_DATE'::
 583'EMAIL'::
 584        see linkgit:git-commit-tree[1]
 585
 586git Diffs
 587~~~~~~~~~
 588'GIT_DIFF_OPTS'::
 589        Only valid setting is "--unified=??" or "-u??" to set the
 590        number of context lines shown when a unified diff is created.
 591        This takes precedence over any "-U" or "--unified" option
 592        value passed on the git diff command line.
 593
 594'GIT_EXTERNAL_DIFF'::
 595        When the environment variable 'GIT_EXTERNAL_DIFF' is set, the
 596        program named by it is called, instead of the diff invocation
 597        described above.  For a path that is added, removed, or modified,
 598        'GIT_EXTERNAL_DIFF' is called with 7 parameters:
 599
 600        path old-file old-hex old-mode new-file new-hex new-mode
 601+
 602where:
 603
 604        <old|new>-file:: are files GIT_EXTERNAL_DIFF can use to read the
 605                         contents of <old|new>,
 606        <old|new>-hex:: are the 40-hexdigit SHA1 hashes,
 607        <old|new>-mode:: are the octal representation of the file modes.
 608
 609+
 610The file parameters can point at the user's working file
 611(e.g. `new-file` in "git-diff-files"), `/dev/null` (e.g. `old-file`
 612when a new file is added), or a temporary file (e.g. `old-file` in the
 613index).  'GIT_EXTERNAL_DIFF' should not worry about unlinking the
 614temporary file --- it is removed when 'GIT_EXTERNAL_DIFF' exits.
 615+
 616For a path that is unmerged, 'GIT_EXTERNAL_DIFF' is called with 1
 617parameter, <path>.
 618
 619other
 620~~~~~
 621'GIT_MERGE_VERBOSITY'::
 622        A number controlling the amount of output shown by
 623        the recursive merge strategy.  Overrides merge.verbosity.
 624        See linkgit:git-merge[1]
 625
 626'GIT_PAGER'::
 627        This environment variable overrides `$PAGER`. If it is set
 628        to an empty string or to the value "cat", git will not launch
 629        a pager.  See also the `core.pager` option in
 630        linkgit:git-config[1].
 631
 632'GIT_SSH'::
 633        If this environment variable is set then 'git fetch'
 634        and 'git push' will use this command instead
 635        of 'ssh' when they need to connect to a remote system.
 636        The '$GIT_SSH' command will be given exactly two arguments:
 637        the 'username@host' (or just 'host') from the URL and the
 638        shell command to execute on that remote system.
 639+
 640To pass options to the program that you want to list in GIT_SSH
 641you will need to wrap the program and options into a shell script,
 642then set GIT_SSH to refer to the shell script.
 643+
 644Usually it is easier to configure any desired options through your
 645personal `.ssh/config` file.  Please consult your ssh documentation
 646for further details.
 647
 648'GIT_ASKPASS'::
 649        If this environment variable is set, then git commands which need to
 650        acquire passwords or passphrases (e.g. for HTTP or IMAP authentication)
 651        will call this program with a suitable prompt as command line argument
 652        and read the password from its STDOUT. See also the 'core.askpass'
 653        option in linkgit:git-config[1].
 654
 655'GIT_FLUSH'::
 656        If this environment variable is set to "1", then commands such
 657        as 'git blame' (in incremental mode), 'git rev-list', 'git log',
 658        and 'git whatchanged' will force a flush of the output stream
 659        after each commit-oriented record have been flushed.   If this
 660        variable is set to "0", the output of these commands will be done
 661        using completely buffered I/O.   If this environment variable is
 662        not set, git will choose buffered or record-oriented flushing
 663        based on whether stdout appears to be redirected to a file or not.
 664
 665'GIT_TRACE'::
 666        If this variable is set to "1", "2" or "true" (comparison
 667        is case insensitive), git will print `trace:` messages on
 668        stderr telling about alias expansion, built-in command
 669        execution and external command execution.
 670        If this variable is set to an integer value greater than 1
 671        and lower than 10 (strictly) then git will interpret this
 672        value as an open file descriptor and will try to write the
 673        trace messages into this file descriptor.
 674        Alternatively, if this variable is set to an absolute path
 675        (starting with a '/' character), git will interpret this
 676        as a file path and will try to write the trace messages
 677        into it.
 678
 679Discussion[[Discussion]]
 680------------------------
 681
 682More detail on the following is available from the
 683link:user-manual.html#git-concepts[git concepts chapter of the
 684user-manual] and linkgit:gitcore-tutorial[7].
 685
 686A git project normally consists of a working directory with a ".git"
 687subdirectory at the top level.  The .git directory contains, among other
 688things, a compressed object database representing the complete history
 689of the project, an "index" file which links that history to the current
 690contents of the working tree, and named pointers into that history such
 691as tags and branch heads.
 692
 693The object database contains objects of three main types: blobs, which
 694hold file data; trees, which point to blobs and other trees to build up
 695directory hierarchies; and commits, which each reference a single tree
 696and some number of parent commits.
 697
 698The commit, equivalent to what other systems call a "changeset" or
 699"version", represents a step in the project's history, and each parent
 700represents an immediately preceding step.  Commits with more than one
 701parent represent merges of independent lines of development.
 702
 703All objects are named by the SHA1 hash of their contents, normally
 704written as a string of 40 hex digits.  Such names are globally unique.
 705The entire history leading up to a commit can be vouched for by signing
 706just that commit.  A fourth object type, the tag, is provided for this
 707purpose.
 708
 709When first created, objects are stored in individual files, but for
 710efficiency may later be compressed together into "pack files".
 711
 712Named pointers called refs mark interesting points in history.  A ref
 713may contain the SHA1 name of an object or the name of another ref.  Refs
 714with names beginning `ref/head/` contain the SHA1 name of the most
 715recent commit (or "head") of a branch under development.  SHA1 names of
 716tags of interest are stored under `ref/tags/`.  A special ref named
 717`HEAD` contains the name of the currently checked-out branch.
 718
 719The index file is initialized with a list of all paths and, for each
 720path, a blob object and a set of attributes.  The blob object represents
 721the contents of the file as of the head of the current branch.  The
 722attributes (last modified time, size, etc.) are taken from the
 723corresponding file in the working tree.  Subsequent changes to the
 724working tree can be found by comparing these attributes.  The index may
 725be updated with new content, and new commits may be created from the
 726content stored in the index.
 727
 728The index is also capable of storing multiple entries (called "stages")
 729for a given pathname.  These stages are used to hold the various
 730unmerged version of a file when a merge is in progress.
 731
 732Authors
 733-------
 734* git's founding father is Linus Torvalds <torvalds@osdl.org>.
 735* The current git nurse is Junio C Hamano <gitster@pobox.com>.
 736* The git potty was written by Andreas Ericsson <ae@op5.se>.
 737* General upbringing is handled by the git-list <git@vger.kernel.org>.
 738
 739Documentation
 740--------------
 741The documentation for git suite was started by David Greaves
 742<david@dgreaves.com>, and later enhanced greatly by the
 743contributors on the git-list <git@vger.kernel.org>.
 744
 745Reporting Bugs
 746--------------
 747
 748Report bugs to the Git mailing list <git@vger.kernel.org> where the
 749development and maintenance is primarily done.  You do not have to be
 750subscribed to the list to send a message there.
 751
 752SEE ALSO
 753--------
 754linkgit:gittutorial[7], linkgit:gittutorial-2[7],
 755link:everyday.html[Everyday Git], linkgit:gitcvs-migration[7],
 756linkgit:gitglossary[7], linkgit:gitcore-tutorial[7],
 757linkgit:gitcli[7], link:user-manual.html[The Git User's Manual],
 758linkgit:gitworkflows[7]
 759
 760GIT
 761---
 762Part of the linkgit:git[1] suite