Documentation / git.txton commit Merge branch 'js/detached-stash' (b480d38)
   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:v1.7.2.3/git.html[documentation for release 1.7.2.3]
  48
  49* release notes for
  50  link:RelNotes-1.7.2.3.txt[1.7.2.3],
  51  link:RelNotes-1.7.2.2.txt[1.7.2.2],
  52  link:RelNotes-1.7.2.1.txt[1.7.2.1],
  53  link:RelNotes-1.7.2.txt[1.7.2].
  54
  55* link:v1.7.1.2/git.html[documentation for release 1.7.1.2]
  56
  57* release notes for
  58  link:RelNotes-1.7.1.2.txt[1.7.1.2],
  59  link:RelNotes-1.7.1.1.txt[1.7.1.1],
  60  link:RelNotes-1.7.1.txt[1.7.1].
  61
  62* link:v1.7.0.7/git.html[documentation for release 1.7.0.7]
  63
  64* release notes for
  65  link:RelNotes-1.7.0.7.txt[1.7.0.7],
  66  link:RelNotes-1.7.0.6.txt[1.7.0.6],
  67  link:RelNotes-1.7.0.5.txt[1.7.0.5],
  68  link:RelNotes-1.7.0.4.txt[1.7.0.4],
  69  link:RelNotes-1.7.0.3.txt[1.7.0.3],
  70  link:RelNotes-1.7.0.2.txt[1.7.0.2],
  71  link:RelNotes-1.7.0.1.txt[1.7.0.1],
  72  link:RelNotes-1.7.0.txt[1.7.0].
  73
  74* link:v1.6.6.2/git.html[documentation for release 1.6.6.2]
  75
  76* release notes for
  77  link:RelNotes-1.6.6.2.txt[1.6.6.2],
  78  link:RelNotes-1.6.6.1.txt[1.6.6.1],
  79  link:RelNotes-1.6.6.txt[1.6.6].
  80
  81* link:v1.6.5.8/git.html[documentation for release 1.6.5.8]
  82
  83* release notes for
  84  link:RelNotes-1.6.5.8.txt[1.6.5.8],
  85  link:RelNotes-1.6.5.7.txt[1.6.5.7],
  86  link:RelNotes-1.6.5.6.txt[1.6.5.6],
  87  link:RelNotes-1.6.5.5.txt[1.6.5.5],
  88  link:RelNotes-1.6.5.4.txt[1.6.5.4],
  89  link:RelNotes-1.6.5.3.txt[1.6.5.3],
  90  link:RelNotes-1.6.5.2.txt[1.6.5.2],
  91  link:RelNotes-1.6.5.1.txt[1.6.5.1],
  92  link:RelNotes-1.6.5.txt[1.6.5].
  93
  94* link:v1.6.4.4/git.html[documentation for release 1.6.4.4]
  95
  96* release notes for
  97  link:RelNotes-1.6.4.4.txt[1.6.4.4],
  98  link:RelNotes-1.6.4.3.txt[1.6.4.3],
  99  link:RelNotes-1.6.4.2.txt[1.6.4.2],
 100  link:RelNotes-1.6.4.1.txt[1.6.4.1],
 101  link:RelNotes-1.6.4.txt[1.6.4].
 102
 103* link:v1.6.3.4/git.html[documentation for release 1.6.3.4]
 104
 105* release notes for
 106  link:RelNotes-1.6.3.4.txt[1.6.3.4],
 107  link:RelNotes-1.6.3.3.txt[1.6.3.3],
 108  link:RelNotes-1.6.3.2.txt[1.6.3.2],
 109  link:RelNotes-1.6.3.1.txt[1.6.3.1],
 110  link:RelNotes-1.6.3.txt[1.6.3].
 111
 112* release notes for
 113  link:RelNotes-1.6.2.5.txt[1.6.2.5],
 114  link:RelNotes-1.6.2.4.txt[1.6.2.4],
 115  link:RelNotes-1.6.2.3.txt[1.6.2.3],
 116  link:RelNotes-1.6.2.2.txt[1.6.2.2],
 117  link:RelNotes-1.6.2.1.txt[1.6.2.1],
 118  link:RelNotes-1.6.2.txt[1.6.2].
 119
 120* link:v1.6.1.3/git.html[documentation for release 1.6.1.3]
 121
 122* release notes for
 123  link:RelNotes-1.6.1.3.txt[1.6.1.3],
 124  link:RelNotes-1.6.1.2.txt[1.6.1.2],
 125  link:RelNotes-1.6.1.1.txt[1.6.1.1],
 126  link:RelNotes-1.6.1.txt[1.6.1].
 127
 128* link:v1.6.0.6/git.html[documentation for release 1.6.0.6]
 129
 130* release notes for
 131  link:RelNotes-1.6.0.6.txt[1.6.0.6],
 132  link:RelNotes-1.6.0.5.txt[1.6.0.5],
 133  link:RelNotes-1.6.0.4.txt[1.6.0.4],
 134  link:RelNotes-1.6.0.3.txt[1.6.0.3],
 135  link:RelNotes-1.6.0.2.txt[1.6.0.2],
 136  link:RelNotes-1.6.0.1.txt[1.6.0.1],
 137  link:RelNotes-1.6.0.txt[1.6.0].
 138
 139* link:v1.5.6.6/git.html[documentation for release 1.5.6.6]
 140
 141* release notes for
 142  link:RelNotes-1.5.6.6.txt[1.5.6.6],
 143  link:RelNotes-1.5.6.5.txt[1.5.6.5],
 144  link:RelNotes-1.5.6.4.txt[1.5.6.4],
 145  link:RelNotes-1.5.6.3.txt[1.5.6.3],
 146  link:RelNotes-1.5.6.2.txt[1.5.6.2],
 147  link:RelNotes-1.5.6.1.txt[1.5.6.1],
 148  link:RelNotes-1.5.6.txt[1.5.6].
 149
 150* link:v1.5.5.6/git.html[documentation for release 1.5.5.6]
 151
 152* release notes for
 153  link:RelNotes-1.5.5.6.txt[1.5.5.6],
 154  link:RelNotes-1.5.5.5.txt[1.5.5.5],
 155  link:RelNotes-1.5.5.4.txt[1.5.5.4],
 156  link:RelNotes-1.5.5.3.txt[1.5.5.3],
 157  link:RelNotes-1.5.5.2.txt[1.5.5.2],
 158  link:RelNotes-1.5.5.1.txt[1.5.5.1],
 159  link:RelNotes-1.5.5.txt[1.5.5].
 160
 161* link:v1.5.4.7/git.html[documentation for release 1.5.4.7]
 162
 163* release notes for
 164  link:RelNotes-1.5.4.7.txt[1.5.4.7],
 165  link:RelNotes-1.5.4.6.txt[1.5.4.6],
 166  link:RelNotes-1.5.4.5.txt[1.5.4.5],
 167  link:RelNotes-1.5.4.4.txt[1.5.4.4],
 168  link:RelNotes-1.5.4.3.txt[1.5.4.3],
 169  link:RelNotes-1.5.4.2.txt[1.5.4.2],
 170  link:RelNotes-1.5.4.1.txt[1.5.4.1],
 171  link:RelNotes-1.5.4.txt[1.5.4].
 172
 173* link:v1.5.3.8/git.html[documentation for release 1.5.3.8]
 174
 175* release notes for
 176  link:RelNotes-1.5.3.8.txt[1.5.3.8],
 177  link:RelNotes-1.5.3.7.txt[1.5.3.7],
 178  link:RelNotes-1.5.3.6.txt[1.5.3.6],
 179  link:RelNotes-1.5.3.5.txt[1.5.3.5],
 180  link:RelNotes-1.5.3.4.txt[1.5.3.4],
 181  link:RelNotes-1.5.3.3.txt[1.5.3.3],
 182  link:RelNotes-1.5.3.2.txt[1.5.3.2],
 183  link:RelNotes-1.5.3.1.txt[1.5.3.1],
 184  link:RelNotes-1.5.3.txt[1.5.3].
 185
 186* link:v1.5.2.5/git.html[documentation for release 1.5.2.5]
 187
 188* release notes for
 189  link:RelNotes-1.5.2.5.txt[1.5.2.5],
 190  link:RelNotes-1.5.2.4.txt[1.5.2.4],
 191  link:RelNotes-1.5.2.3.txt[1.5.2.3],
 192  link:RelNotes-1.5.2.2.txt[1.5.2.2],
 193  link:RelNotes-1.5.2.1.txt[1.5.2.1],
 194  link:RelNotes-1.5.2.txt[1.5.2].
 195
 196* link:v1.5.1.6/git.html[documentation for release 1.5.1.6]
 197
 198* release notes for
 199  link:RelNotes-1.5.1.6.txt[1.5.1.6],
 200  link:RelNotes-1.5.1.5.txt[1.5.1.5],
 201  link:RelNotes-1.5.1.4.txt[1.5.1.4],
 202  link:RelNotes-1.5.1.3.txt[1.5.1.3],
 203  link:RelNotes-1.5.1.2.txt[1.5.1.2],
 204  link:RelNotes-1.5.1.1.txt[1.5.1.1],
 205  link:RelNotes-1.5.1.txt[1.5.1].
 206
 207* link:v1.5.0.7/git.html[documentation for release 1.5.0.7]
 208
 209* release notes for
 210  link:RelNotes-1.5.0.7.txt[1.5.0.7],
 211  link:RelNotes-1.5.0.6.txt[1.5.0.6],
 212  link:RelNotes-1.5.0.5.txt[1.5.0.5],
 213  link:RelNotes-1.5.0.3.txt[1.5.0.3],
 214  link:RelNotes-1.5.0.2.txt[1.5.0.2],
 215  link:RelNotes-1.5.0.1.txt[1.5.0.1],
 216  link:RelNotes-1.5.0.txt[1.5.0].
 217
 218* documentation for release link:v1.4.4.4/git.html[1.4.4.4],
 219  link:v1.3.3/git.html[1.3.3],
 220  link:v1.2.6/git.html[1.2.6],
 221  link:v1.0.13/git.html[1.0.13].
 222
 223============
 224
 225endif::stalenotes[]
 226
 227OPTIONS
 228-------
 229--version::
 230        Prints the git suite version that the 'git' program came from.
 231
 232--help::
 233        Prints the synopsis and a list of the most commonly used
 234        commands. If the option '--all' or '-a' is given then all
 235        available commands are printed. If a git command is named this
 236        option will bring up the manual page for that command.
 237+
 238Other options are available to control how the manual page is
 239displayed. See linkgit:git-help[1] for more information,
 240because `git --help ...` is converted internally into `git
 241help ...`.
 242
 243-c <name>=<value>::
 244        Pass a configuration parameter to the command. The value
 245        given will override values from configuration files.
 246        The <name> is expected in the same format as listed by
 247        'git config' (subkeys separated by dots).
 248
 249--exec-path::
 250        Path to wherever your core git programs are installed.
 251        This can also be controlled by setting the GIT_EXEC_PATH
 252        environment variable. If no path is given, 'git' will print
 253        the current setting and then exit.
 254
 255--html-path::
 256        Print the path to wherever your git HTML documentation is installed
 257        and exit.
 258
 259-p::
 260--paginate::
 261        Pipe all output into 'less' (or if set, $PAGER) if standard
 262        output is a terminal.  This overrides the `pager.<cmd>`
 263        configuration options (see the "Configuration Mechanism" section
 264        below).
 265
 266--no-pager::
 267        Do not pipe git output into a pager.
 268
 269--git-dir=<path>::
 270        Set the path to the repository. This can also be controlled by
 271        setting the GIT_DIR environment variable. It can be an absolute
 272        path or relative path to current working directory.
 273
 274--work-tree=<path>::
 275        Set the path to the working tree.  The value will not be
 276        used in combination with repositories found automatically in
 277        a .git directory (i.e. $GIT_DIR is not set).
 278        This can also be controlled by setting the GIT_WORK_TREE
 279        environment variable and the core.worktree configuration
 280        variable. It can be an absolute path or relative path to
 281        the directory specified by --git-dir or GIT_DIR.
 282        Note: If --git-dir or GIT_DIR are specified but none of
 283        --work-tree, GIT_WORK_TREE and core.worktree is specified,
 284        the current working directory is regarded as the top directory
 285        of your working tree.
 286
 287--bare::
 288        Treat the repository as a bare repository.  If GIT_DIR
 289        environment is not set, it is set to the current working
 290        directory.
 291
 292--no-replace-objects::
 293        Do not use replacement refs to replace git objects. See
 294        linkgit:git-replace[1] for more information.
 295
 296
 297FURTHER DOCUMENTATION
 298---------------------
 299
 300See the references above to get started using git.  The following is
 301probably more detail than necessary for a first-time user.
 302
 303The link:user-manual.html#git-concepts[git concepts chapter of the
 304user-manual] and linkgit:gitcore-tutorial[7] both provide
 305introductions to the underlying git architecture.
 306
 307See linkgit:gitworkflows[7] for an overview of recommended workflows.
 308
 309See also the link:howto-index.html[howto] documents for some useful
 310examples.
 311
 312The internals are documented in the
 313link:technical/api-index.html[GIT API documentation].
 314
 315GIT COMMANDS
 316------------
 317
 318We divide git into high level ("porcelain") commands and low level
 319("plumbing") commands.
 320
 321High-level commands (porcelain)
 322-------------------------------
 323
 324We separate the porcelain commands into the main commands and some
 325ancillary user utilities.
 326
 327Main porcelain commands
 328~~~~~~~~~~~~~~~~~~~~~~~
 329
 330include::cmds-mainporcelain.txt[]
 331
 332Ancillary Commands
 333~~~~~~~~~~~~~~~~~~
 334Manipulators:
 335
 336include::cmds-ancillarymanipulators.txt[]
 337
 338Interrogators:
 339
 340include::cmds-ancillaryinterrogators.txt[]
 341
 342
 343Interacting with Others
 344~~~~~~~~~~~~~~~~~~~~~~~
 345
 346These commands are to interact with foreign SCM and with other
 347people via patch over e-mail.
 348
 349include::cmds-foreignscminterface.txt[]
 350
 351
 352Low-level commands (plumbing)
 353-----------------------------
 354
 355Although git includes its
 356own porcelain layer, its low-level commands are sufficient to support
 357development of alternative porcelains.  Developers of such porcelains
 358might start by reading about linkgit:git-update-index[1] and
 359linkgit:git-read-tree[1].
 360
 361The interface (input, output, set of options and the semantics)
 362to these low-level commands are meant to be a lot more stable
 363than Porcelain level commands, because these commands are
 364primarily for scripted use.  The interface to Porcelain commands
 365on the other hand are subject to change in order to improve the
 366end user experience.
 367
 368The following description divides
 369the low-level commands into commands that manipulate objects (in
 370the repository, index, and working tree), commands that interrogate and
 371compare objects, and commands that move objects and references between
 372repositories.
 373
 374
 375Manipulation commands
 376~~~~~~~~~~~~~~~~~~~~~
 377
 378include::cmds-plumbingmanipulators.txt[]
 379
 380
 381Interrogation commands
 382~~~~~~~~~~~~~~~~~~~~~~
 383
 384include::cmds-plumbinginterrogators.txt[]
 385
 386In general, the interrogate commands do not touch the files in
 387the working tree.
 388
 389
 390Synching repositories
 391~~~~~~~~~~~~~~~~~~~~~
 392
 393include::cmds-synchingrepositories.txt[]
 394
 395The following are helper commands used by the above; end users
 396typically do not use them directly.
 397
 398include::cmds-synchelpers.txt[]
 399
 400
 401Internal helper commands
 402~~~~~~~~~~~~~~~~~~~~~~~~
 403
 404These are internal helper commands used by other commands; end
 405users typically do not use them directly.
 406
 407include::cmds-purehelpers.txt[]
 408
 409
 410Configuration Mechanism
 411-----------------------
 412
 413Starting from 0.99.9 (actually mid 0.99.8.GIT), `.git/config` file
 414is used to hold per-repository configuration options.  It is a
 415simple text file modeled after `.ini` format familiar to some
 416people.  Here is an example:
 417
 418------------
 419#
 420# A '#' or ';' character indicates a comment.
 421#
 422
 423; core variables
 424[core]
 425        ; Don't trust file modes
 426        filemode = false
 427
 428; user identity
 429[user]
 430        name = "Junio C Hamano"
 431        email = "junkio@twinsun.com"
 432
 433------------
 434
 435Various commands read from the configuration file and adjust
 436their operation accordingly.  See linkgit:git-config[1] for a
 437list.
 438
 439
 440Identifier Terminology
 441----------------------
 442<object>::
 443        Indicates the object name for any type of object.
 444
 445<blob>::
 446        Indicates a blob object name.
 447
 448<tree>::
 449        Indicates a tree object name.
 450
 451<commit>::
 452        Indicates a commit object name.
 453
 454<tree-ish>::
 455        Indicates a tree, commit or tag object name.  A
 456        command that takes a <tree-ish> argument ultimately wants to
 457        operate on a <tree> object but automatically dereferences
 458        <commit> and <tag> objects that point at a <tree>.
 459
 460<commit-ish>::
 461        Indicates a commit or tag object name.  A
 462        command that takes a <commit-ish> argument ultimately wants to
 463        operate on a <commit> object but automatically dereferences
 464        <tag> objects that point at a <commit>.
 465
 466<type>::
 467        Indicates that an object type is required.
 468        Currently one of: `blob`, `tree`, `commit`, or `tag`.
 469
 470<file>::
 471        Indicates a filename - almost always relative to the
 472        root of the tree structure `GIT_INDEX_FILE` describes.
 473
 474Symbolic Identifiers
 475--------------------
 476Any git command accepting any <object> can also use the following
 477symbolic notation:
 478
 479HEAD::
 480        indicates the head of the current branch (i.e. the
 481        contents of `$GIT_DIR/HEAD`).
 482
 483<tag>::
 484        a valid tag 'name'
 485        (i.e. the contents of `$GIT_DIR/refs/tags/<tag>`).
 486
 487<head>::
 488        a valid head 'name'
 489        (i.e. the contents of `$GIT_DIR/refs/heads/<head>`).
 490
 491For a more complete list of ways to spell object names, see
 492"SPECIFYING REVISIONS" section in linkgit:gitrevisions[1].
 493
 494
 495File/Directory Structure
 496------------------------
 497
 498Please see the linkgit:gitrepository-layout[5] document.
 499
 500Read linkgit:githooks[5] for more details about each hook.
 501
 502Higher level SCMs may provide and manage additional information in the
 503`$GIT_DIR`.
 504
 505
 506Terminology
 507-----------
 508Please see linkgit:gitglossary[7].
 509
 510
 511Environment Variables
 512---------------------
 513Various git commands use the following environment variables:
 514
 515The git Repository
 516~~~~~~~~~~~~~~~~~~
 517These environment variables apply to 'all' core git commands. Nb: it
 518is worth noting that they may be used/overridden by SCMS sitting above
 519git so take care if using Cogito etc.
 520
 521'GIT_INDEX_FILE'::
 522        This environment allows the specification of an alternate
 523        index file. If not specified, the default of `$GIT_DIR/index`
 524        is used.
 525
 526'GIT_OBJECT_DIRECTORY'::
 527        If the object storage directory is specified via this
 528        environment variable then the sha1 directories are created
 529        underneath - otherwise the default `$GIT_DIR/objects`
 530        directory is used.
 531
 532'GIT_ALTERNATE_OBJECT_DIRECTORIES'::
 533        Due to the immutable nature of git objects, old objects can be
 534        archived into shared, read-only directories. This variable
 535        specifies a ":" separated (on Windows ";" separated) list
 536        of git object directories which can be used to search for git
 537        objects. New objects will not be written to these directories.
 538
 539'GIT_DIR'::
 540        If the 'GIT_DIR' environment variable is set then it
 541        specifies a path to use instead of the default `.git`
 542        for the base of the repository.
 543
 544'GIT_WORK_TREE'::
 545        Set the path to the working tree.  The value will not be
 546        used in combination with repositories found automatically in
 547        a .git directory (i.e. $GIT_DIR is not set).
 548        This can also be controlled by the '--work-tree' command line
 549        option and the core.worktree configuration variable.
 550
 551'GIT_CEILING_DIRECTORIES'::
 552        This should be a colon-separated list of absolute paths.
 553        If set, it is a list of directories that git should not chdir
 554        up into while looking for a repository directory.
 555        It will not exclude the current working directory or
 556        a GIT_DIR set on the command line or in the environment.
 557        (Useful for excluding slow-loading network directories.)
 558
 559'GIT_DISCOVERY_ACROSS_FILESYSTEM'::
 560        When run in a directory that does not have ".git" repository
 561        directory, git tries to find such a directory in the parent
 562        directories to find the top of the working tree, but by default it
 563        does not cross filesystem boundaries.  This environment variable
 564        can be set to true to tell git not to stop at filesystem
 565        boundaries.  Like 'GIT_CEILING_DIRECTORIES', this will not affect
 566        an explicit repository directory set via 'GIT_DIR' or on the
 567        command line.
 568
 569git Commits
 570~~~~~~~~~~~
 571'GIT_AUTHOR_NAME'::
 572'GIT_AUTHOR_EMAIL'::
 573'GIT_AUTHOR_DATE'::
 574'GIT_COMMITTER_NAME'::
 575'GIT_COMMITTER_EMAIL'::
 576'GIT_COMMITTER_DATE'::
 577'EMAIL'::
 578        see linkgit:git-commit-tree[1]
 579
 580git Diffs
 581~~~~~~~~~
 582'GIT_DIFF_OPTS'::
 583        Only valid setting is "--unified=??" or "-u??" to set the
 584        number of context lines shown when a unified diff is created.
 585        This takes precedence over any "-U" or "--unified" option
 586        value passed on the git diff command line.
 587
 588'GIT_EXTERNAL_DIFF'::
 589        When the environment variable 'GIT_EXTERNAL_DIFF' is set, the
 590        program named by it is called, instead of the diff invocation
 591        described above.  For a path that is added, removed, or modified,
 592        'GIT_EXTERNAL_DIFF' is called with 7 parameters:
 593
 594        path old-file old-hex old-mode new-file new-hex new-mode
 595+
 596where:
 597
 598        <old|new>-file:: are files GIT_EXTERNAL_DIFF can use to read the
 599                         contents of <old|new>,
 600        <old|new>-hex:: are the 40-hexdigit SHA1 hashes,
 601        <old|new>-mode:: are the octal representation of the file modes.
 602
 603+
 604The file parameters can point at the user's working file
 605(e.g. `new-file` in "git-diff-files"), `/dev/null` (e.g. `old-file`
 606when a new file is added), or a temporary file (e.g. `old-file` in the
 607index).  'GIT_EXTERNAL_DIFF' should not worry about unlinking the
 608temporary file --- it is removed when 'GIT_EXTERNAL_DIFF' exits.
 609+
 610For a path that is unmerged, 'GIT_EXTERNAL_DIFF' is called with 1
 611parameter, <path>.
 612
 613other
 614~~~~~
 615'GIT_MERGE_VERBOSITY'::
 616        A number controlling the amount of output shown by
 617        the recursive merge strategy.  Overrides merge.verbosity.
 618        See linkgit:git-merge[1]
 619
 620'GIT_PAGER'::
 621        This environment variable overrides `$PAGER`. If it is set
 622        to an empty string or to the value "cat", git will not launch
 623        a pager.  See also the `core.pager` option in
 624        linkgit:git-config[1].
 625
 626'GIT_SSH'::
 627        If this environment variable is set then 'git fetch'
 628        and 'git push' will use this command instead
 629        of 'ssh' when they need to connect to a remote system.
 630        The '$GIT_SSH' command will be given exactly two arguments:
 631        the 'username@host' (or just 'host') from the URL and the
 632        shell command to execute on that remote system.
 633+
 634To pass options to the program that you want to list in GIT_SSH
 635you will need to wrap the program and options into a shell script,
 636then set GIT_SSH to refer to the shell script.
 637+
 638Usually it is easier to configure any desired options through your
 639personal `.ssh/config` file.  Please consult your ssh documentation
 640for further details.
 641
 642'GIT_FLUSH'::
 643        If this environment variable is set to "1", then commands such
 644        as 'git blame' (in incremental mode), 'git rev-list', 'git log',
 645        and 'git whatchanged' will force a flush of the output stream
 646        after each commit-oriented record have been flushed.   If this
 647        variable is set to "0", the output of these commands will be done
 648        using completely buffered I/O.   If this environment variable is
 649        not set, git will choose buffered or record-oriented flushing
 650        based on whether stdout appears to be redirected to a file or not.
 651
 652'GIT_TRACE'::
 653        If this variable is set to "1", "2" or "true" (comparison
 654        is case insensitive), git will print `trace:` messages on
 655        stderr telling about alias expansion, built-in command
 656        execution and external command execution.
 657        If this variable is set to an integer value greater than 1
 658        and lower than 10 (strictly) then git will interpret this
 659        value as an open file descriptor and will try to write the
 660        trace messages into this file descriptor.
 661        Alternatively, if this variable is set to an absolute path
 662        (starting with a '/' character), git will interpret this
 663        as a file path and will try to write the trace messages
 664        into it.
 665
 666Discussion[[Discussion]]
 667------------------------
 668
 669More detail on the following is available from the
 670link:user-manual.html#git-concepts[git concepts chapter of the
 671user-manual] and linkgit:gitcore-tutorial[7].
 672
 673A git project normally consists of a working directory with a ".git"
 674subdirectory at the top level.  The .git directory contains, among other
 675things, a compressed object database representing the complete history
 676of the project, an "index" file which links that history to the current
 677contents of the working tree, and named pointers into that history such
 678as tags and branch heads.
 679
 680The object database contains objects of three main types: blobs, which
 681hold file data; trees, which point to blobs and other trees to build up
 682directory hierarchies; and commits, which each reference a single tree
 683and some number of parent commits.
 684
 685The commit, equivalent to what other systems call a "changeset" or
 686"version", represents a step in the project's history, and each parent
 687represents an immediately preceding step.  Commits with more than one
 688parent represent merges of independent lines of development.
 689
 690All objects are named by the SHA1 hash of their contents, normally
 691written as a string of 40 hex digits.  Such names are globally unique.
 692The entire history leading up to a commit can be vouched for by signing
 693just that commit.  A fourth object type, the tag, is provided for this
 694purpose.
 695
 696When first created, objects are stored in individual files, but for
 697efficiency may later be compressed together into "pack files".
 698
 699Named pointers called refs mark interesting points in history.  A ref
 700may contain the SHA1 name of an object or the name of another ref.  Refs
 701with names beginning `ref/head/` contain the SHA1 name of the most
 702recent commit (or "head") of a branch under development.  SHA1 names of
 703tags of interest are stored under `ref/tags/`.  A special ref named
 704`HEAD` contains the name of the currently checked-out branch.
 705
 706The index file is initialized with a list of all paths and, for each
 707path, a blob object and a set of attributes.  The blob object represents
 708the contents of the file as of the head of the current branch.  The
 709attributes (last modified time, size, etc.) are taken from the
 710corresponding file in the working tree.  Subsequent changes to the
 711working tree can be found by comparing these attributes.  The index may
 712be updated with new content, and new commits may be created from the
 713content stored in the index.
 714
 715The index is also capable of storing multiple entries (called "stages")
 716for a given pathname.  These stages are used to hold the various
 717unmerged version of a file when a merge is in progress.
 718
 719Authors
 720-------
 721* git's founding father is Linus Torvalds <torvalds@osdl.org>.
 722* The current git nurse is Junio C Hamano <gitster@pobox.com>.
 723* The git potty was written by Andreas Ericsson <ae@op5.se>.
 724* General upbringing is handled by the git-list <git@vger.kernel.org>.
 725
 726Documentation
 727--------------
 728The documentation for git suite was started by David Greaves
 729<david@dgreaves.com>, and later enhanced greatly by the
 730contributors on the git-list <git@vger.kernel.org>.
 731
 732Reporting Bugs
 733--------------
 734
 735Report bugs to the Git mailing list <git@vger.kernel.org> where the
 736development and maintenance is primarily done.  You do not have to be
 737subscribed to the list to send a message there.
 738
 739SEE ALSO
 740--------
 741linkgit:gittutorial[7], linkgit:gittutorial-2[7],
 742link:everyday.html[Everyday Git], linkgit:gitcvs-migration[7],
 743linkgit:gitglossary[7], linkgit:gitcore-tutorial[7],
 744linkgit:gitcli[7], link:user-manual.html[The Git User's Manual],
 745linkgit:gitworkflows[7]
 746
 747GIT
 748---
 749Part of the linkgit:git[1] suite