Documentation / git.txton commit Merge branch 'js/maint-1.6.6-send-pack-stateless-rpc-deadlock-fix' into js/maint-send-pack-stateless-rpc-deadlock-fix (1c1f046)
   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    [--help] COMMAND [ARGS]
  16
  17DESCRIPTION
  18-----------
  19Git is a fast, scalable, distributed revision control system with an
  20unusually rich command set that provides both high-level operations
  21and full access to internals.
  22
  23See linkgit:gittutorial[7] to get started, then see
  24link:everyday.html[Everyday Git] for a useful minimum set of commands, and
  25"man git-commandname" for documentation of each command.  CVS users may
  26also want to read linkgit:gitcvs-migration[7].  See
  27the link:user-manual.html[Git User's Manual] for a more in-depth
  28introduction.
  29
  30The COMMAND is either a name of a Git command (see below) or an alias
  31as defined in the configuration file (see linkgit:git-config[1]).
  32
  33Formatted and hyperlinked version of the latest git
  34documentation can be viewed at
  35`http://www.kernel.org/pub/software/scm/git/docs/`.
  36
  37ifdef::stalenotes[]
  38[NOTE]
  39============
  40
  41You are reading the documentation for the latest (possibly
  42unreleased) version of git, that is available from 'master'
  43branch of the `git.git` repository.
  44Documentation for older releases are available here:
  45
  46* link:v1.7.0.1/git.html[documentation for release 1.7.0.1]
  47
  48* release notes for
  49  link:RelNotes-1.7.0.1.txt[1.7.0.1],
  50  link:RelNotes-1.7.0.txt[1.7.0].
  51
  52* link:v1.6.6.2/git.html[documentation for release 1.6.6.2]
  53
  54* release notes for
  55  link:RelNotes-1.6.6.2.txt[1.6.6.2],
  56  link:RelNotes-1.6.6.1.txt[1.6.6.1],
  57  link:RelNotes-1.6.6.txt[1.6.6].
  58
  59* link:v1.6.5.8/git.html[documentation for release 1.6.5.8]
  60
  61* release notes for
  62  link:RelNotes-1.6.5.8.txt[1.6.5.8],
  63  link:RelNotes-1.6.5.7.txt[1.6.5.7],
  64  link:RelNotes-1.6.5.6.txt[1.6.5.6],
  65  link:RelNotes-1.6.5.5.txt[1.6.5.5],
  66  link:RelNotes-1.6.5.4.txt[1.6.5.4],
  67  link:RelNotes-1.6.5.3.txt[1.6.5.3],
  68  link:RelNotes-1.6.5.2.txt[1.6.5.2],
  69  link:RelNotes-1.6.5.1.txt[1.6.5.1],
  70  link:RelNotes-1.6.5.txt[1.6.5].
  71
  72* link:v1.6.4.4/git.html[documentation for release 1.6.4.4]
  73
  74* release notes for
  75  link:RelNotes-1.6.4.4.txt[1.6.4.4],
  76  link:RelNotes-1.6.4.3.txt[1.6.4.3],
  77  link:RelNotes-1.6.4.2.txt[1.6.4.2],
  78  link:RelNotes-1.6.4.1.txt[1.6.4.1],
  79  link:RelNotes-1.6.4.txt[1.6.4].
  80
  81* link:v1.6.3.4/git.html[documentation for release 1.6.3.4]
  82
  83* release notes for
  84  link:RelNotes-1.6.3.4.txt[1.6.3.4],
  85  link:RelNotes-1.6.3.3.txt[1.6.3.3],
  86  link:RelNotes-1.6.3.2.txt[1.6.3.2],
  87  link:RelNotes-1.6.3.1.txt[1.6.3.1],
  88  link:RelNotes-1.6.3.txt[1.6.3].
  89
  90* release notes for
  91  link:RelNotes-1.6.2.5.txt[1.6.2.5],
  92  link:RelNotes-1.6.2.4.txt[1.6.2.4],
  93  link:RelNotes-1.6.2.3.txt[1.6.2.3],
  94  link:RelNotes-1.6.2.2.txt[1.6.2.2],
  95  link:RelNotes-1.6.2.1.txt[1.6.2.1],
  96  link:RelNotes-1.6.2.txt[1.6.2].
  97
  98* link:v1.6.1.3/git.html[documentation for release 1.6.1.3]
  99
 100* release notes for
 101  link:RelNotes-1.6.1.3.txt[1.6.1.3],
 102  link:RelNotes-1.6.1.2.txt[1.6.1.2],
 103  link:RelNotes-1.6.1.1.txt[1.6.1.1],
 104  link:RelNotes-1.6.1.txt[1.6.1].
 105
 106* link:v1.6.0.6/git.html[documentation for release 1.6.0.6]
 107
 108* release notes for
 109  link:RelNotes-1.6.0.6.txt[1.6.0.6],
 110  link:RelNotes-1.6.0.5.txt[1.6.0.5],
 111  link:RelNotes-1.6.0.4.txt[1.6.0.4],
 112  link:RelNotes-1.6.0.3.txt[1.6.0.3],
 113  link:RelNotes-1.6.0.2.txt[1.6.0.2],
 114  link:RelNotes-1.6.0.1.txt[1.6.0.1],
 115  link:RelNotes-1.6.0.txt[1.6.0].
 116
 117* link:v1.5.6.6/git.html[documentation for release 1.5.6.6]
 118
 119* release notes for
 120  link:RelNotes-1.5.6.6.txt[1.5.6.6],
 121  link:RelNotes-1.5.6.5.txt[1.5.6.5],
 122  link:RelNotes-1.5.6.4.txt[1.5.6.4],
 123  link:RelNotes-1.5.6.3.txt[1.5.6.3],
 124  link:RelNotes-1.5.6.2.txt[1.5.6.2],
 125  link:RelNotes-1.5.6.1.txt[1.5.6.1],
 126  link:RelNotes-1.5.6.txt[1.5.6].
 127
 128* link:v1.5.5.6/git.html[documentation for release 1.5.5.6]
 129
 130* release notes for
 131  link:RelNotes-1.5.5.6.txt[1.5.5.6],
 132  link:RelNotes-1.5.5.5.txt[1.5.5.5],
 133  link:RelNotes-1.5.5.4.txt[1.5.5.4],
 134  link:RelNotes-1.5.5.3.txt[1.5.5.3],
 135  link:RelNotes-1.5.5.2.txt[1.5.5.2],
 136  link:RelNotes-1.5.5.1.txt[1.5.5.1],
 137  link:RelNotes-1.5.5.txt[1.5.5].
 138
 139* link:v1.5.4.7/git.html[documentation for release 1.5.4.7]
 140
 141* release notes for
 142  link:RelNotes-1.5.4.7.txt[1.5.4.7],
 143  link:RelNotes-1.5.4.6.txt[1.5.4.6],
 144  link:RelNotes-1.5.4.5.txt[1.5.4.5],
 145  link:RelNotes-1.5.4.4.txt[1.5.4.4],
 146  link:RelNotes-1.5.4.3.txt[1.5.4.3],
 147  link:RelNotes-1.5.4.2.txt[1.5.4.2],
 148  link:RelNotes-1.5.4.1.txt[1.5.4.1],
 149  link:RelNotes-1.5.4.txt[1.5.4].
 150
 151* link:v1.5.3.8/git.html[documentation for release 1.5.3.8]
 152
 153* release notes for
 154  link:RelNotes-1.5.3.8.txt[1.5.3.8],
 155  link:RelNotes-1.5.3.7.txt[1.5.3.7],
 156  link:RelNotes-1.5.3.6.txt[1.5.3.6],
 157  link:RelNotes-1.5.3.5.txt[1.5.3.5],
 158  link:RelNotes-1.5.3.4.txt[1.5.3.4],
 159  link:RelNotes-1.5.3.3.txt[1.5.3.3],
 160  link:RelNotes-1.5.3.2.txt[1.5.3.2],
 161  link:RelNotes-1.5.3.1.txt[1.5.3.1],
 162  link:RelNotes-1.5.3.txt[1.5.3].
 163
 164* link:v1.5.2.5/git.html[documentation for release 1.5.2.5]
 165
 166* release notes for
 167  link:RelNotes-1.5.2.5.txt[1.5.2.5],
 168  link:RelNotes-1.5.2.4.txt[1.5.2.4],
 169  link:RelNotes-1.5.2.3.txt[1.5.2.3],
 170  link:RelNotes-1.5.2.2.txt[1.5.2.2],
 171  link:RelNotes-1.5.2.1.txt[1.5.2.1],
 172  link:RelNotes-1.5.2.txt[1.5.2].
 173
 174* link:v1.5.1.6/git.html[documentation for release 1.5.1.6]
 175
 176* release notes for
 177  link:RelNotes-1.5.1.6.txt[1.5.1.6],
 178  link:RelNotes-1.5.1.5.txt[1.5.1.5],
 179  link:RelNotes-1.5.1.4.txt[1.5.1.4],
 180  link:RelNotes-1.5.1.3.txt[1.5.1.3],
 181  link:RelNotes-1.5.1.2.txt[1.5.1.2],
 182  link:RelNotes-1.5.1.1.txt[1.5.1.1],
 183  link:RelNotes-1.5.1.txt[1.5.1].
 184
 185* link:v1.5.0.7/git.html[documentation for release 1.5.0.7]
 186
 187* release notes for
 188  link:RelNotes-1.5.0.7.txt[1.5.0.7],
 189  link:RelNotes-1.5.0.6.txt[1.5.0.6],
 190  link:RelNotes-1.5.0.5.txt[1.5.0.5],
 191  link:RelNotes-1.5.0.3.txt[1.5.0.3],
 192  link:RelNotes-1.5.0.2.txt[1.5.0.2],
 193  link:RelNotes-1.5.0.1.txt[1.5.0.1],
 194  link:RelNotes-1.5.0.txt[1.5.0].
 195
 196* documentation for release link:v1.4.4.4/git.html[1.4.4.4],
 197  link:v1.3.3/git.html[1.3.3],
 198  link:v1.2.6/git.html[1.2.6],
 199  link:v1.0.13/git.html[1.0.13].
 200
 201============
 202
 203endif::stalenotes[]
 204
 205OPTIONS
 206-------
 207--version::
 208        Prints the git suite version that the 'git' program came from.
 209
 210--help::
 211        Prints the synopsis and a list of the most commonly used
 212        commands. If the option '--all' or '-a' is given then all
 213        available commands are printed. If a git command is named this
 214        option will bring up the manual page for that command.
 215+
 216Other options are available to control how the manual page is
 217displayed. See linkgit:git-help[1] for more information,
 218because `git --help ...` is converted internally into `git
 219help ...`.
 220
 221--exec-path::
 222        Path to wherever your core git programs are installed.
 223        This can also be controlled by setting the GIT_EXEC_PATH
 224        environment variable. If no path is given, 'git' will print
 225        the current setting and then exit.
 226
 227--html-path::
 228        Print the path to wherever your git HTML documentation is installed
 229        and exit.
 230
 231-p::
 232--paginate::
 233        Pipe all output into 'less' (or if set, $PAGER) if standard
 234        output is a terminal.  This overrides the `pager.<cmd>`
 235        configuration options (see the "Configuration Mechanism" section
 236        below).
 237
 238--no-pager::
 239        Do not pipe git output into a pager.
 240
 241--git-dir=<path>::
 242        Set the path to the repository. This can also be controlled by
 243        setting the GIT_DIR environment variable. It can be an absolute
 244        path or relative path to current working directory.
 245
 246--work-tree=<path>::
 247        Set the path to the working tree.  The value will not be
 248        used in combination with repositories found automatically in
 249        a .git directory (i.e. $GIT_DIR is not set).
 250        This can also be controlled by setting the GIT_WORK_TREE
 251        environment variable and the core.worktree configuration
 252        variable. It can be an absolute path or relative path to
 253        the directory specified by --git-dir or GIT_DIR.
 254        Note: If --git-dir or GIT_DIR are specified but none of
 255        --work-tree, GIT_WORK_TREE and core.worktree is specified,
 256        the current working directory is regarded as the top directory
 257        of your working tree.
 258
 259--bare::
 260        Treat the repository as a bare repository.  If GIT_DIR
 261        environment is not set, it is set to the current working
 262        directory.
 263
 264--no-replace-objects::
 265        Do not use replacement refs to replace git objects. See
 266        linkgit:git-replace[1] for more information.
 267
 268
 269FURTHER DOCUMENTATION
 270---------------------
 271
 272See the references above to get started using git.  The following is
 273probably more detail than necessary for a first-time user.
 274
 275The link:user-manual.html#git-concepts[git concepts chapter of the
 276user-manual] and linkgit:gitcore-tutorial[7] both provide
 277introductions to the underlying git architecture.
 278
 279See linkgit:gitworkflows[7] for an overview of recommended workflows.
 280
 281See also the link:howto-index.html[howto] documents for some useful
 282examples.
 283
 284The internals are documented in the
 285link:technical/api-index.html[GIT API documentation].
 286
 287GIT COMMANDS
 288------------
 289
 290We divide git into high level ("porcelain") commands and low level
 291("plumbing") commands.
 292
 293High-level commands (porcelain)
 294-------------------------------
 295
 296We separate the porcelain commands into the main commands and some
 297ancillary user utilities.
 298
 299Main porcelain commands
 300~~~~~~~~~~~~~~~~~~~~~~~
 301
 302include::cmds-mainporcelain.txt[]
 303
 304Ancillary Commands
 305~~~~~~~~~~~~~~~~~~
 306Manipulators:
 307
 308include::cmds-ancillarymanipulators.txt[]
 309
 310Interrogators:
 311
 312include::cmds-ancillaryinterrogators.txt[]
 313
 314
 315Interacting with Others
 316~~~~~~~~~~~~~~~~~~~~~~~
 317
 318These commands are to interact with foreign SCM and with other
 319people via patch over e-mail.
 320
 321include::cmds-foreignscminterface.txt[]
 322
 323
 324Low-level commands (plumbing)
 325-----------------------------
 326
 327Although git includes its
 328own porcelain layer, its low-level commands are sufficient to support
 329development of alternative porcelains.  Developers of such porcelains
 330might start by reading about linkgit:git-update-index[1] and
 331linkgit:git-read-tree[1].
 332
 333The interface (input, output, set of options and the semantics)
 334to these low-level commands are meant to be a lot more stable
 335than Porcelain level commands, because these commands are
 336primarily for scripted use.  The interface to Porcelain commands
 337on the other hand are subject to change in order to improve the
 338end user experience.
 339
 340The following description divides
 341the low-level commands into commands that manipulate objects (in
 342the repository, index, and working tree), commands that interrogate and
 343compare objects, and commands that move objects and references between
 344repositories.
 345
 346
 347Manipulation commands
 348~~~~~~~~~~~~~~~~~~~~~
 349
 350include::cmds-plumbingmanipulators.txt[]
 351
 352
 353Interrogation commands
 354~~~~~~~~~~~~~~~~~~~~~~
 355
 356include::cmds-plumbinginterrogators.txt[]
 357
 358In general, the interrogate commands do not touch the files in
 359the working tree.
 360
 361
 362Synching repositories
 363~~~~~~~~~~~~~~~~~~~~~
 364
 365include::cmds-synchingrepositories.txt[]
 366
 367The following are helper commands used by the above; end users
 368typically do not use them directly.
 369
 370include::cmds-synchelpers.txt[]
 371
 372
 373Internal helper commands
 374~~~~~~~~~~~~~~~~~~~~~~~~
 375
 376These are internal helper commands used by other commands; end
 377users typically do not use them directly.
 378
 379include::cmds-purehelpers.txt[]
 380
 381
 382Configuration Mechanism
 383-----------------------
 384
 385Starting from 0.99.9 (actually mid 0.99.8.GIT), `.git/config` file
 386is used to hold per-repository configuration options.  It is a
 387simple text file modeled after `.ini` format familiar to some
 388people.  Here is an example:
 389
 390------------
 391#
 392# A '#' or ';' character indicates a comment.
 393#
 394
 395; core variables
 396[core]
 397        ; Don't trust file modes
 398        filemode = false
 399
 400; user identity
 401[user]
 402        name = "Junio C Hamano"
 403        email = "junkio@twinsun.com"
 404
 405------------
 406
 407Various commands read from the configuration file and adjust
 408their operation accordingly.  See linkgit:git-config[1] for a
 409list.
 410
 411
 412Identifier Terminology
 413----------------------
 414<object>::
 415        Indicates the object name for any type of object.
 416
 417<blob>::
 418        Indicates a blob object name.
 419
 420<tree>::
 421        Indicates a tree object name.
 422
 423<commit>::
 424        Indicates a commit object name.
 425
 426<tree-ish>::
 427        Indicates a tree, commit or tag object name.  A
 428        command that takes a <tree-ish> argument ultimately wants to
 429        operate on a <tree> object but automatically dereferences
 430        <commit> and <tag> objects that point at a <tree>.
 431
 432<commit-ish>::
 433        Indicates a commit or tag object name.  A
 434        command that takes a <commit-ish> argument ultimately wants to
 435        operate on a <commit> object but automatically dereferences
 436        <tag> objects that point at a <commit>.
 437
 438<type>::
 439        Indicates that an object type is required.
 440        Currently one of: `blob`, `tree`, `commit`, or `tag`.
 441
 442<file>::
 443        Indicates a filename - almost always relative to the
 444        root of the tree structure `GIT_INDEX_FILE` describes.
 445
 446Symbolic Identifiers
 447--------------------
 448Any git command accepting any <object> can also use the following
 449symbolic notation:
 450
 451HEAD::
 452        indicates the head of the current branch (i.e. the
 453        contents of `$GIT_DIR/HEAD`).
 454
 455<tag>::
 456        a valid tag 'name'
 457        (i.e. the contents of `$GIT_DIR/refs/tags/<tag>`).
 458
 459<head>::
 460        a valid head 'name'
 461        (i.e. the contents of `$GIT_DIR/refs/heads/<head>`).
 462
 463For a more complete list of ways to spell object names, see
 464"SPECIFYING REVISIONS" section in linkgit:git-rev-parse[1].
 465
 466
 467File/Directory Structure
 468------------------------
 469
 470Please see the linkgit:gitrepository-layout[5] document.
 471
 472Read linkgit:githooks[5] for more details about each hook.
 473
 474Higher level SCMs may provide and manage additional information in the
 475`$GIT_DIR`.
 476
 477
 478Terminology
 479-----------
 480Please see linkgit:gitglossary[7].
 481
 482
 483Environment Variables
 484---------------------
 485Various git commands use the following environment variables:
 486
 487The git Repository
 488~~~~~~~~~~~~~~~~~~
 489These environment variables apply to 'all' core git commands. Nb: it
 490is worth noting that they may be used/overridden by SCMS sitting above
 491git so take care if using Cogito etc.
 492
 493'GIT_INDEX_FILE'::
 494        This environment allows the specification of an alternate
 495        index file. If not specified, the default of `$GIT_DIR/index`
 496        is used.
 497
 498'GIT_OBJECT_DIRECTORY'::
 499        If the object storage directory is specified via this
 500        environment variable then the sha1 directories are created
 501        underneath - otherwise the default `$GIT_DIR/objects`
 502        directory is used.
 503
 504'GIT_ALTERNATE_OBJECT_DIRECTORIES'::
 505        Due to the immutable nature of git objects, old objects can be
 506        archived into shared, read-only directories. This variable
 507        specifies a ":" separated (on Windows ";" separated) list
 508        of git object directories which can be used to search for git
 509        objects. New objects will not be written to these directories.
 510
 511'GIT_DIR'::
 512        If the 'GIT_DIR' environment variable is set then it
 513        specifies a path to use instead of the default `.git`
 514        for the base of the repository.
 515
 516'GIT_WORK_TREE'::
 517        Set the path to the working tree.  The value will not be
 518        used in combination with repositories found automatically in
 519        a .git directory (i.e. $GIT_DIR is not set).
 520        This can also be controlled by the '--work-tree' command line
 521        option and the core.worktree configuration variable.
 522
 523'GIT_CEILING_DIRECTORIES'::
 524        This should be a colon-separated list of absolute paths.
 525        If set, it is a list of directories that git should not chdir
 526        up into while looking for a repository directory.
 527        It will not exclude the current working directory or
 528        a GIT_DIR set on the command line or in the environment.
 529        (Useful for excluding slow-loading network directories.)
 530
 531git Commits
 532~~~~~~~~~~~
 533'GIT_AUTHOR_NAME'::
 534'GIT_AUTHOR_EMAIL'::
 535'GIT_AUTHOR_DATE'::
 536'GIT_COMMITTER_NAME'::
 537'GIT_COMMITTER_EMAIL'::
 538'GIT_COMMITTER_DATE'::
 539'EMAIL'::
 540        see linkgit:git-commit-tree[1]
 541
 542git Diffs
 543~~~~~~~~~
 544'GIT_DIFF_OPTS'::
 545        Only valid setting is "--unified=??" or "-u??" to set the
 546        number of context lines shown when a unified diff is created.
 547        This takes precedence over any "-U" or "--unified" option
 548        value passed on the git diff command line.
 549
 550'GIT_EXTERNAL_DIFF'::
 551        When the environment variable 'GIT_EXTERNAL_DIFF' is set, the
 552        program named by it is called, instead of the diff invocation
 553        described above.  For a path that is added, removed, or modified,
 554        'GIT_EXTERNAL_DIFF' is called with 7 parameters:
 555
 556        path old-file old-hex old-mode new-file new-hex new-mode
 557+
 558where:
 559
 560        <old|new>-file:: are files GIT_EXTERNAL_DIFF can use to read the
 561                         contents of <old|new>,
 562        <old|new>-hex:: are the 40-hexdigit SHA1 hashes,
 563        <old|new>-mode:: are the octal representation of the file modes.
 564
 565+
 566The file parameters can point at the user's working file
 567(e.g. `new-file` in "git-diff-files"), `/dev/null` (e.g. `old-file`
 568when a new file is added), or a temporary file (e.g. `old-file` in the
 569index).  'GIT_EXTERNAL_DIFF' should not worry about unlinking the
 570temporary file --- it is removed when 'GIT_EXTERNAL_DIFF' exits.
 571+
 572For a path that is unmerged, 'GIT_EXTERNAL_DIFF' is called with 1
 573parameter, <path>.
 574
 575other
 576~~~~~
 577'GIT_MERGE_VERBOSITY'::
 578        A number controlling the amount of output shown by
 579        the recursive merge strategy.  Overrides merge.verbosity.
 580        See linkgit:git-merge[1]
 581
 582'GIT_PAGER'::
 583        This environment variable overrides `$PAGER`. If it is set
 584        to an empty string or to the value "cat", git will not launch
 585        a pager.  See also the `core.pager` option in
 586        linkgit:git-config[1].
 587
 588'GIT_SSH'::
 589        If this environment variable is set then 'git fetch'
 590        and 'git push' will use this command instead
 591        of 'ssh' when they need to connect to a remote system.
 592        The '$GIT_SSH' command will be given exactly two arguments:
 593        the 'username@host' (or just 'host') from the URL and the
 594        shell command to execute on that remote system.
 595+
 596To pass options to the program that you want to list in GIT_SSH
 597you will need to wrap the program and options into a shell script,
 598then set GIT_SSH to refer to the shell script.
 599+
 600Usually it is easier to configure any desired options through your
 601personal `.ssh/config` file.  Please consult your ssh documentation
 602for further details.
 603
 604'GIT_FLUSH'::
 605        If this environment variable is set to "1", then commands such
 606        as 'git blame' (in incremental mode), 'git rev-list', 'git log',
 607        and 'git whatchanged' will force a flush of the output stream
 608        after each commit-oriented record have been flushed.   If this
 609        variable is set to "0", the output of these commands will be done
 610        using completely buffered I/O.   If this environment variable is
 611        not set, git will choose buffered or record-oriented flushing
 612        based on whether stdout appears to be redirected to a file or not.
 613
 614'GIT_TRACE'::
 615        If this variable is set to "1", "2" or "true" (comparison
 616        is case insensitive), git will print `trace:` messages on
 617        stderr telling about alias expansion, built-in command
 618        execution and external command execution.
 619        If this variable is set to an integer value greater than 1
 620        and lower than 10 (strictly) then git will interpret this
 621        value as an open file descriptor and will try to write the
 622        trace messages into this file descriptor.
 623        Alternatively, if this variable is set to an absolute path
 624        (starting with a '/' character), git will interpret this
 625        as a file path and will try to write the trace messages
 626        into it.
 627
 628Discussion[[Discussion]]
 629------------------------
 630
 631More detail on the following is available from the
 632link:user-manual.html#git-concepts[git concepts chapter of the
 633user-manual] and linkgit:gitcore-tutorial[7].
 634
 635A git project normally consists of a working directory with a ".git"
 636subdirectory at the top level.  The .git directory contains, among other
 637things, a compressed object database representing the complete history
 638of the project, an "index" file which links that history to the current
 639contents of the working tree, and named pointers into that history such
 640as tags and branch heads.
 641
 642The object database contains objects of three main types: blobs, which
 643hold file data; trees, which point to blobs and other trees to build up
 644directory hierarchies; and commits, which each reference a single tree
 645and some number of parent commits.
 646
 647The commit, equivalent to what other systems call a "changeset" or
 648"version", represents a step in the project's history, and each parent
 649represents an immediately preceding step.  Commits with more than one
 650parent represent merges of independent lines of development.
 651
 652All objects are named by the SHA1 hash of their contents, normally
 653written as a string of 40 hex digits.  Such names are globally unique.
 654The entire history leading up to a commit can be vouched for by signing
 655just that commit.  A fourth object type, the tag, is provided for this
 656purpose.
 657
 658When first created, objects are stored in individual files, but for
 659efficiency may later be compressed together into "pack files".
 660
 661Named pointers called refs mark interesting points in history.  A ref
 662may contain the SHA1 name of an object or the name of another ref.  Refs
 663with names beginning `ref/head/` contain the SHA1 name of the most
 664recent commit (or "head") of a branch under development.  SHA1 names of
 665tags of interest are stored under `ref/tags/`.  A special ref named
 666`HEAD` contains the name of the currently checked-out branch.
 667
 668The index file is initialized with a list of all paths and, for each
 669path, a blob object and a set of attributes.  The blob object represents
 670the contents of the file as of the head of the current branch.  The
 671attributes (last modified time, size, etc.) are taken from the
 672corresponding file in the working tree.  Subsequent changes to the
 673working tree can be found by comparing these attributes.  The index may
 674be updated with new content, and new commits may be created from the
 675content stored in the index.
 676
 677The index is also capable of storing multiple entries (called "stages")
 678for a given pathname.  These stages are used to hold the various
 679unmerged version of a file when a merge is in progress.
 680
 681Authors
 682-------
 683* git's founding father is Linus Torvalds <torvalds@osdl.org>.
 684* The current git nurse is Junio C Hamano <gitster@pobox.com>.
 685* The git potty was written by Andreas Ericsson <ae@op5.se>.
 686* General upbringing is handled by the git-list <git@vger.kernel.org>.
 687
 688Documentation
 689--------------
 690The documentation for git suite was started by David Greaves
 691<david@dgreaves.com>, and later enhanced greatly by the
 692contributors on the git-list <git@vger.kernel.org>.
 693
 694SEE ALSO
 695--------
 696linkgit:gittutorial[7], linkgit:gittutorial-2[7],
 697link:everyday.html[Everyday Git], linkgit:gitcvs-migration[7],
 698linkgit:gitglossary[7], linkgit:gitcore-tutorial[7],
 699linkgit:gitcli[7], link:user-manual.html[The Git User's Manual],
 700linkgit:gitworkflows[7]
 701
 702GIT
 703---
 704Part of the linkgit:git[1] suite