Documentation / git.txton commit Merge branch 'pb/log-first-parent-p-m' (797d443)
   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:v1.7.0.3/git.html[documentation for release 1.7.0.3]
  47
  48* release notes for
  49  link:RelNotes-1.7.0.3.txt[1.7.0.3],
  50  link:RelNotes-1.7.0.2.txt[1.7.0.2],
  51  link:RelNotes-1.7.0.1.txt[1.7.0.1],
  52  link:RelNotes-1.7.0.txt[1.7.0].
  53
  54* link:v1.6.6.2/git.html[documentation for release 1.6.6.2]
  55
  56* release notes for
  57  link:RelNotes-1.6.6.2.txt[1.6.6.2],
  58  link:RelNotes-1.6.6.1.txt[1.6.6.1],
  59  link:RelNotes-1.6.6.txt[1.6.6].
  60
  61* link:v1.6.5.8/git.html[documentation for release 1.6.5.8]
  62
  63* release notes for
  64  link:RelNotes-1.6.5.8.txt[1.6.5.8],
  65  link:RelNotes-1.6.5.7.txt[1.6.5.7],
  66  link:RelNotes-1.6.5.6.txt[1.6.5.6],
  67  link:RelNotes-1.6.5.5.txt[1.6.5.5],
  68  link:RelNotes-1.6.5.4.txt[1.6.5.4],
  69  link:RelNotes-1.6.5.3.txt[1.6.5.3],
  70  link:RelNotes-1.6.5.2.txt[1.6.5.2],
  71  link:RelNotes-1.6.5.1.txt[1.6.5.1],
  72  link:RelNotes-1.6.5.txt[1.6.5].
  73
  74* link:v1.6.4.4/git.html[documentation for release 1.6.4.4]
  75
  76* release notes for
  77  link:RelNotes-1.6.4.4.txt[1.6.4.4],
  78  link:RelNotes-1.6.4.3.txt[1.6.4.3],
  79  link:RelNotes-1.6.4.2.txt[1.6.4.2],
  80  link:RelNotes-1.6.4.1.txt[1.6.4.1],
  81  link:RelNotes-1.6.4.txt[1.6.4].
  82
  83* link:v1.6.3.4/git.html[documentation for release 1.6.3.4]
  84
  85* release notes for
  86  link:RelNotes-1.6.3.4.txt[1.6.3.4],
  87  link:RelNotes-1.6.3.3.txt[1.6.3.3],
  88  link:RelNotes-1.6.3.2.txt[1.6.3.2],
  89  link:RelNotes-1.6.3.1.txt[1.6.3.1],
  90  link:RelNotes-1.6.3.txt[1.6.3].
  91
  92* release notes for
  93  link:RelNotes-1.6.2.5.txt[1.6.2.5],
  94  link:RelNotes-1.6.2.4.txt[1.6.2.4],
  95  link:RelNotes-1.6.2.3.txt[1.6.2.3],
  96  link:RelNotes-1.6.2.2.txt[1.6.2.2],
  97  link:RelNotes-1.6.2.1.txt[1.6.2.1],
  98  link:RelNotes-1.6.2.txt[1.6.2].
  99
 100* link:v1.6.1.3/git.html[documentation for release 1.6.1.3]
 101
 102* release notes for
 103  link:RelNotes-1.6.1.3.txt[1.6.1.3],
 104  link:RelNotes-1.6.1.2.txt[1.6.1.2],
 105  link:RelNotes-1.6.1.1.txt[1.6.1.1],
 106  link:RelNotes-1.6.1.txt[1.6.1].
 107
 108* link:v1.6.0.6/git.html[documentation for release 1.6.0.6]
 109
 110* release notes for
 111  link:RelNotes-1.6.0.6.txt[1.6.0.6],
 112  link:RelNotes-1.6.0.5.txt[1.6.0.5],
 113  link:RelNotes-1.6.0.4.txt[1.6.0.4],
 114  link:RelNotes-1.6.0.3.txt[1.6.0.3],
 115  link:RelNotes-1.6.0.2.txt[1.6.0.2],
 116  link:RelNotes-1.6.0.1.txt[1.6.0.1],
 117  link:RelNotes-1.6.0.txt[1.6.0].
 118
 119* link:v1.5.6.6/git.html[documentation for release 1.5.6.6]
 120
 121* release notes for
 122  link:RelNotes-1.5.6.6.txt[1.5.6.6],
 123  link:RelNotes-1.5.6.5.txt[1.5.6.5],
 124  link:RelNotes-1.5.6.4.txt[1.5.6.4],
 125  link:RelNotes-1.5.6.3.txt[1.5.6.3],
 126  link:RelNotes-1.5.6.2.txt[1.5.6.2],
 127  link:RelNotes-1.5.6.1.txt[1.5.6.1],
 128  link:RelNotes-1.5.6.txt[1.5.6].
 129
 130* link:v1.5.5.6/git.html[documentation for release 1.5.5.6]
 131
 132* release notes for
 133  link:RelNotes-1.5.5.6.txt[1.5.5.6],
 134  link:RelNotes-1.5.5.5.txt[1.5.5.5],
 135  link:RelNotes-1.5.5.4.txt[1.5.5.4],
 136  link:RelNotes-1.5.5.3.txt[1.5.5.3],
 137  link:RelNotes-1.5.5.2.txt[1.5.5.2],
 138  link:RelNotes-1.5.5.1.txt[1.5.5.1],
 139  link:RelNotes-1.5.5.txt[1.5.5].
 140
 141* link:v1.5.4.7/git.html[documentation for release 1.5.4.7]
 142
 143* release notes for
 144  link:RelNotes-1.5.4.7.txt[1.5.4.7],
 145  link:RelNotes-1.5.4.6.txt[1.5.4.6],
 146  link:RelNotes-1.5.4.5.txt[1.5.4.5],
 147  link:RelNotes-1.5.4.4.txt[1.5.4.4],
 148  link:RelNotes-1.5.4.3.txt[1.5.4.3],
 149  link:RelNotes-1.5.4.2.txt[1.5.4.2],
 150  link:RelNotes-1.5.4.1.txt[1.5.4.1],
 151  link:RelNotes-1.5.4.txt[1.5.4].
 152
 153* link:v1.5.3.8/git.html[documentation for release 1.5.3.8]
 154
 155* release notes for
 156  link:RelNotes-1.5.3.8.txt[1.5.3.8],
 157  link:RelNotes-1.5.3.7.txt[1.5.3.7],
 158  link:RelNotes-1.5.3.6.txt[1.5.3.6],
 159  link:RelNotes-1.5.3.5.txt[1.5.3.5],
 160  link:RelNotes-1.5.3.4.txt[1.5.3.4],
 161  link:RelNotes-1.5.3.3.txt[1.5.3.3],
 162  link:RelNotes-1.5.3.2.txt[1.5.3.2],
 163  link:RelNotes-1.5.3.1.txt[1.5.3.1],
 164  link:RelNotes-1.5.3.txt[1.5.3].
 165
 166* link:v1.5.2.5/git.html[documentation for release 1.5.2.5]
 167
 168* release notes for
 169  link:RelNotes-1.5.2.5.txt[1.5.2.5],
 170  link:RelNotes-1.5.2.4.txt[1.5.2.4],
 171  link:RelNotes-1.5.2.3.txt[1.5.2.3],
 172  link:RelNotes-1.5.2.2.txt[1.5.2.2],
 173  link:RelNotes-1.5.2.1.txt[1.5.2.1],
 174  link:RelNotes-1.5.2.txt[1.5.2].
 175
 176* link:v1.5.1.6/git.html[documentation for release 1.5.1.6]
 177
 178* release notes for
 179  link:RelNotes-1.5.1.6.txt[1.5.1.6],
 180  link:RelNotes-1.5.1.5.txt[1.5.1.5],
 181  link:RelNotes-1.5.1.4.txt[1.5.1.4],
 182  link:RelNotes-1.5.1.3.txt[1.5.1.3],
 183  link:RelNotes-1.5.1.2.txt[1.5.1.2],
 184  link:RelNotes-1.5.1.1.txt[1.5.1.1],
 185  link:RelNotes-1.5.1.txt[1.5.1].
 186
 187* link:v1.5.0.7/git.html[documentation for release 1.5.0.7]
 188
 189* release notes for
 190  link:RelNotes-1.5.0.7.txt[1.5.0.7],
 191  link:RelNotes-1.5.0.6.txt[1.5.0.6],
 192  link:RelNotes-1.5.0.5.txt[1.5.0.5],
 193  link:RelNotes-1.5.0.3.txt[1.5.0.3],
 194  link:RelNotes-1.5.0.2.txt[1.5.0.2],
 195  link:RelNotes-1.5.0.1.txt[1.5.0.1],
 196  link:RelNotes-1.5.0.txt[1.5.0].
 197
 198* documentation for release link:v1.4.4.4/git.html[1.4.4.4],
 199  link:v1.3.3/git.html[1.3.3],
 200  link:v1.2.6/git.html[1.2.6],
 201  link:v1.0.13/git.html[1.0.13].
 202
 203============
 204
 205endif::stalenotes[]
 206
 207OPTIONS
 208-------
 209--version::
 210        Prints the git suite version that the 'git' program came from.
 211
 212--help::
 213        Prints the synopsis and a list of the most commonly used
 214        commands. If the option '--all' or '-a' is given then all
 215        available commands are printed. If a git command is named this
 216        option will bring up the manual page for that command.
 217+
 218Other options are available to control how the manual page is
 219displayed. See linkgit:git-help[1] for more information,
 220because `git --help ...` is converted internally into `git
 221help ...`.
 222
 223--exec-path::
 224        Path to wherever your core git programs are installed.
 225        This can also be controlled by setting the GIT_EXEC_PATH
 226        environment variable. If no path is given, 'git' will print
 227        the current setting and then exit.
 228
 229--html-path::
 230        Print the path to wherever your git HTML documentation is installed
 231        and exit.
 232
 233-p::
 234--paginate::
 235        Pipe all output into 'less' (or if set, $PAGER) if standard
 236        output is a terminal.  This overrides the `pager.<cmd>`
 237        configuration options (see the "Configuration Mechanism" section
 238        below).
 239
 240--no-pager::
 241        Do not pipe git output into a pager.
 242
 243--git-dir=<path>::
 244        Set the path to the repository. This can also be controlled by
 245        setting the GIT_DIR environment variable. It can be an absolute
 246        path or relative path to current working directory.
 247
 248--work-tree=<path>::
 249        Set the path to the working tree.  The value will not be
 250        used in combination with repositories found automatically in
 251        a .git directory (i.e. $GIT_DIR is not set).
 252        This can also be controlled by setting the GIT_WORK_TREE
 253        environment variable and the core.worktree configuration
 254        variable. It can be an absolute path or relative path to
 255        the directory specified by --git-dir or GIT_DIR.
 256        Note: If --git-dir or GIT_DIR are specified but none of
 257        --work-tree, GIT_WORK_TREE and core.worktree is specified,
 258        the current working directory is regarded as the top directory
 259        of your working tree.
 260
 261--bare::
 262        Treat the repository as a bare repository.  If GIT_DIR
 263        environment is not set, it is set to the current working
 264        directory.
 265
 266--no-replace-objects::
 267        Do not use replacement refs to replace git objects. See
 268        linkgit:git-replace[1] for more information.
 269
 270
 271FURTHER DOCUMENTATION
 272---------------------
 273
 274See the references above to get started using git.  The following is
 275probably more detail than necessary for a first-time user.
 276
 277The link:user-manual.html#git-concepts[git concepts chapter of the
 278user-manual] and linkgit:gitcore-tutorial[7] both provide
 279introductions to the underlying git architecture.
 280
 281See linkgit:gitworkflows[7] for an overview of recommended workflows.
 282
 283See also the link:howto-index.html[howto] documents for some useful
 284examples.
 285
 286The internals are documented in the
 287link:technical/api-index.html[GIT API documentation].
 288
 289GIT COMMANDS
 290------------
 291
 292We divide git into high level ("porcelain") commands and low level
 293("plumbing") commands.
 294
 295High-level commands (porcelain)
 296-------------------------------
 297
 298We separate the porcelain commands into the main commands and some
 299ancillary user utilities.
 300
 301Main porcelain commands
 302~~~~~~~~~~~~~~~~~~~~~~~
 303
 304include::cmds-mainporcelain.txt[]
 305
 306Ancillary Commands
 307~~~~~~~~~~~~~~~~~~
 308Manipulators:
 309
 310include::cmds-ancillarymanipulators.txt[]
 311
 312Interrogators:
 313
 314include::cmds-ancillaryinterrogators.txt[]
 315
 316
 317Interacting with Others
 318~~~~~~~~~~~~~~~~~~~~~~~
 319
 320These commands are to interact with foreign SCM and with other
 321people via patch over e-mail.
 322
 323include::cmds-foreignscminterface.txt[]
 324
 325
 326Low-level commands (plumbing)
 327-----------------------------
 328
 329Although git includes its
 330own porcelain layer, its low-level commands are sufficient to support
 331development of alternative porcelains.  Developers of such porcelains
 332might start by reading about linkgit:git-update-index[1] and
 333linkgit:git-read-tree[1].
 334
 335The interface (input, output, set of options and the semantics)
 336to these low-level commands are meant to be a lot more stable
 337than Porcelain level commands, because these commands are
 338primarily for scripted use.  The interface to Porcelain commands
 339on the other hand are subject to change in order to improve the
 340end user experience.
 341
 342The following description divides
 343the low-level commands into commands that manipulate objects (in
 344the repository, index, and working tree), commands that interrogate and
 345compare objects, and commands that move objects and references between
 346repositories.
 347
 348
 349Manipulation commands
 350~~~~~~~~~~~~~~~~~~~~~
 351
 352include::cmds-plumbingmanipulators.txt[]
 353
 354
 355Interrogation commands
 356~~~~~~~~~~~~~~~~~~~~~~
 357
 358include::cmds-plumbinginterrogators.txt[]
 359
 360In general, the interrogate commands do not touch the files in
 361the working tree.
 362
 363
 364Synching repositories
 365~~~~~~~~~~~~~~~~~~~~~
 366
 367include::cmds-synchingrepositories.txt[]
 368
 369The following are helper commands used by the above; end users
 370typically do not use them directly.
 371
 372include::cmds-synchelpers.txt[]
 373
 374
 375Internal helper commands
 376~~~~~~~~~~~~~~~~~~~~~~~~
 377
 378These are internal helper commands used by other commands; end
 379users typically do not use them directly.
 380
 381include::cmds-purehelpers.txt[]
 382
 383
 384Configuration Mechanism
 385-----------------------
 386
 387Starting from 0.99.9 (actually mid 0.99.8.GIT), `.git/config` file
 388is used to hold per-repository configuration options.  It is a
 389simple text file modeled after `.ini` format familiar to some
 390people.  Here is an example:
 391
 392------------
 393#
 394# A '#' or ';' character indicates a comment.
 395#
 396
 397; core variables
 398[core]
 399        ; Don't trust file modes
 400        filemode = false
 401
 402; user identity
 403[user]
 404        name = "Junio C Hamano"
 405        email = "junkio@twinsun.com"
 406
 407------------
 408
 409Various commands read from the configuration file and adjust
 410their operation accordingly.  See linkgit:git-config[1] for a
 411list.
 412
 413
 414Identifier Terminology
 415----------------------
 416<object>::
 417        Indicates the object name for any type of object.
 418
 419<blob>::
 420        Indicates a blob object name.
 421
 422<tree>::
 423        Indicates a tree object name.
 424
 425<commit>::
 426        Indicates a commit object name.
 427
 428<tree-ish>::
 429        Indicates a tree, commit or tag object name.  A
 430        command that takes a <tree-ish> argument ultimately wants to
 431        operate on a <tree> object but automatically dereferences
 432        <commit> and <tag> objects that point at a <tree>.
 433
 434<commit-ish>::
 435        Indicates a commit or tag object name.  A
 436        command that takes a <commit-ish> argument ultimately wants to
 437        operate on a <commit> object but automatically dereferences
 438        <tag> objects that point at a <commit>.
 439
 440<type>::
 441        Indicates that an object type is required.
 442        Currently one of: `blob`, `tree`, `commit`, or `tag`.
 443
 444<file>::
 445        Indicates a filename - almost always relative to the
 446        root of the tree structure `GIT_INDEX_FILE` describes.
 447
 448Symbolic Identifiers
 449--------------------
 450Any git command accepting any <object> can also use the following
 451symbolic notation:
 452
 453HEAD::
 454        indicates the head of the current branch (i.e. the
 455        contents of `$GIT_DIR/HEAD`).
 456
 457<tag>::
 458        a valid tag 'name'
 459        (i.e. the contents of `$GIT_DIR/refs/tags/<tag>`).
 460
 461<head>::
 462        a valid head 'name'
 463        (i.e. the contents of `$GIT_DIR/refs/heads/<head>`).
 464
 465For a more complete list of ways to spell object names, see
 466"SPECIFYING REVISIONS" section in linkgit:git-rev-parse[1].
 467
 468
 469File/Directory Structure
 470------------------------
 471
 472Please see the linkgit:gitrepository-layout[5] document.
 473
 474Read linkgit:githooks[5] for more details about each hook.
 475
 476Higher level SCMs may provide and manage additional information in the
 477`$GIT_DIR`.
 478
 479
 480Terminology
 481-----------
 482Please see linkgit:gitglossary[7].
 483
 484
 485Environment Variables
 486---------------------
 487Various git commands use the following environment variables:
 488
 489The git Repository
 490~~~~~~~~~~~~~~~~~~
 491These environment variables apply to 'all' core git commands. Nb: it
 492is worth noting that they may be used/overridden by SCMS sitting above
 493git so take care if using Cogito etc.
 494
 495'GIT_INDEX_FILE'::
 496        This environment allows the specification of an alternate
 497        index file. If not specified, the default of `$GIT_DIR/index`
 498        is used.
 499
 500'GIT_OBJECT_DIRECTORY'::
 501        If the object storage directory is specified via this
 502        environment variable then the sha1 directories are created
 503        underneath - otherwise the default `$GIT_DIR/objects`
 504        directory is used.
 505
 506'GIT_ALTERNATE_OBJECT_DIRECTORIES'::
 507        Due to the immutable nature of git objects, old objects can be
 508        archived into shared, read-only directories. This variable
 509        specifies a ":" separated (on Windows ";" separated) list
 510        of git object directories which can be used to search for git
 511        objects. New objects will not be written to these directories.
 512
 513'GIT_DIR'::
 514        If the 'GIT_DIR' environment variable is set then it
 515        specifies a path to use instead of the default `.git`
 516        for the base of the repository.
 517
 518'GIT_WORK_TREE'::
 519        Set the path to the working tree.  The value will not be
 520        used in combination with repositories found automatically in
 521        a .git directory (i.e. $GIT_DIR is not set).
 522        This can also be controlled by the '--work-tree' command line
 523        option and the core.worktree configuration variable.
 524
 525'GIT_CEILING_DIRECTORIES'::
 526        This should be a colon-separated list of absolute paths.
 527        If set, it is a list of directories that git should not chdir
 528        up into while looking for a repository directory.
 529        It will not exclude the current working directory or
 530        a GIT_DIR set on the command line or in the environment.
 531        (Useful for excluding slow-loading network directories.)
 532
 533git Commits
 534~~~~~~~~~~~
 535'GIT_AUTHOR_NAME'::
 536'GIT_AUTHOR_EMAIL'::
 537'GIT_AUTHOR_DATE'::
 538'GIT_COMMITTER_NAME'::
 539'GIT_COMMITTER_EMAIL'::
 540'GIT_COMMITTER_DATE'::
 541'EMAIL'::
 542        see linkgit:git-commit-tree[1]
 543
 544git Diffs
 545~~~~~~~~~
 546'GIT_DIFF_OPTS'::
 547        Only valid setting is "--unified=??" or "-u??" to set the
 548        number of context lines shown when a unified diff is created.
 549        This takes precedence over any "-U" or "--unified" option
 550        value passed on the git diff command line.
 551
 552'GIT_EXTERNAL_DIFF'::
 553        When the environment variable 'GIT_EXTERNAL_DIFF' is set, the
 554        program named by it is called, instead of the diff invocation
 555        described above.  For a path that is added, removed, or modified,
 556        'GIT_EXTERNAL_DIFF' is called with 7 parameters:
 557
 558        path old-file old-hex old-mode new-file new-hex new-mode
 559+
 560where:
 561
 562        <old|new>-file:: are files GIT_EXTERNAL_DIFF can use to read the
 563                         contents of <old|new>,
 564        <old|new>-hex:: are the 40-hexdigit SHA1 hashes,
 565        <old|new>-mode:: are the octal representation of the file modes.
 566
 567+
 568The file parameters can point at the user's working file
 569(e.g. `new-file` in "git-diff-files"), `/dev/null` (e.g. `old-file`
 570when a new file is added), or a temporary file (e.g. `old-file` in the
 571index).  'GIT_EXTERNAL_DIFF' should not worry about unlinking the
 572temporary file --- it is removed when 'GIT_EXTERNAL_DIFF' exits.
 573+
 574For a path that is unmerged, 'GIT_EXTERNAL_DIFF' is called with 1
 575parameter, <path>.
 576
 577other
 578~~~~~
 579'GIT_MERGE_VERBOSITY'::
 580        A number controlling the amount of output shown by
 581        the recursive merge strategy.  Overrides merge.verbosity.
 582        See linkgit:git-merge[1]
 583
 584'GIT_PAGER'::
 585        This environment variable overrides `$PAGER`. If it is set
 586        to an empty string or to the value "cat", git will not launch
 587        a pager.  See also the `core.pager` option in
 588        linkgit:git-config[1].
 589
 590'GIT_SSH'::
 591        If this environment variable is set then 'git fetch'
 592        and 'git push' will use this command instead
 593        of 'ssh' when they need to connect to a remote system.
 594        The '$GIT_SSH' command will be given exactly two arguments:
 595        the 'username@host' (or just 'host') from the URL and the
 596        shell command to execute on that remote system.
 597+
 598To pass options to the program that you want to list in GIT_SSH
 599you will need to wrap the program and options into a shell script,
 600then set GIT_SSH to refer to the shell script.
 601+
 602Usually it is easier to configure any desired options through your
 603personal `.ssh/config` file.  Please consult your ssh documentation
 604for further details.
 605
 606'GIT_FLUSH'::
 607        If this environment variable is set to "1", then commands such
 608        as 'git blame' (in incremental mode), 'git rev-list', 'git log',
 609        and 'git whatchanged' will force a flush of the output stream
 610        after each commit-oriented record have been flushed.   If this
 611        variable is set to "0", the output of these commands will be done
 612        using completely buffered I/O.   If this environment variable is
 613        not set, git will choose buffered or record-oriented flushing
 614        based on whether stdout appears to be redirected to a file or not.
 615
 616'GIT_TRACE'::
 617        If this variable is set to "1", "2" or "true" (comparison
 618        is case insensitive), git will print `trace:` messages on
 619        stderr telling about alias expansion, built-in command
 620        execution and external command execution.
 621        If this variable is set to an integer value greater than 1
 622        and lower than 10 (strictly) then git will interpret this
 623        value as an open file descriptor and will try to write the
 624        trace messages into this file descriptor.
 625        Alternatively, if this variable is set to an absolute path
 626        (starting with a '/' character), git will interpret this
 627        as a file path and will try to write the trace messages
 628        into it.
 629
 630Discussion[[Discussion]]
 631------------------------
 632
 633More detail on the following is available from the
 634link:user-manual.html#git-concepts[git concepts chapter of the
 635user-manual] and linkgit:gitcore-tutorial[7].
 636
 637A git project normally consists of a working directory with a ".git"
 638subdirectory at the top level.  The .git directory contains, among other
 639things, a compressed object database representing the complete history
 640of the project, an "index" file which links that history to the current
 641contents of the working tree, and named pointers into that history such
 642as tags and branch heads.
 643
 644The object database contains objects of three main types: blobs, which
 645hold file data; trees, which point to blobs and other trees to build up
 646directory hierarchies; and commits, which each reference a single tree
 647and some number of parent commits.
 648
 649The commit, equivalent to what other systems call a "changeset" or
 650"version", represents a step in the project's history, and each parent
 651represents an immediately preceding step.  Commits with more than one
 652parent represent merges of independent lines of development.
 653
 654All objects are named by the SHA1 hash of their contents, normally
 655written as a string of 40 hex digits.  Such names are globally unique.
 656The entire history leading up to a commit can be vouched for by signing
 657just that commit.  A fourth object type, the tag, is provided for this
 658purpose.
 659
 660When first created, objects are stored in individual files, but for
 661efficiency may later be compressed together into "pack files".
 662
 663Named pointers called refs mark interesting points in history.  A ref
 664may contain the SHA1 name of an object or the name of another ref.  Refs
 665with names beginning `ref/head/` contain the SHA1 name of the most
 666recent commit (or "head") of a branch under development.  SHA1 names of
 667tags of interest are stored under `ref/tags/`.  A special ref named
 668`HEAD` contains the name of the currently checked-out branch.
 669
 670The index file is initialized with a list of all paths and, for each
 671path, a blob object and a set of attributes.  The blob object represents
 672the contents of the file as of the head of the current branch.  The
 673attributes (last modified time, size, etc.) are taken from the
 674corresponding file in the working tree.  Subsequent changes to the
 675working tree can be found by comparing these attributes.  The index may
 676be updated with new content, and new commits may be created from the
 677content stored in the index.
 678
 679The index is also capable of storing multiple entries (called "stages")
 680for a given pathname.  These stages are used to hold the various
 681unmerged version of a file when a merge is in progress.
 682
 683Authors
 684-------
 685* git's founding father is Linus Torvalds <torvalds@osdl.org>.
 686* The current git nurse is Junio C Hamano <gitster@pobox.com>.
 687* The git potty was written by Andreas Ericsson <ae@op5.se>.
 688* General upbringing is handled by the git-list <git@vger.kernel.org>.
 689
 690Documentation
 691--------------
 692The documentation for git suite was started by David Greaves
 693<david@dgreaves.com>, and later enhanced greatly by the
 694contributors on the git-list <git@vger.kernel.org>.
 695
 696SEE ALSO
 697--------
 698linkgit:gittutorial[7], linkgit:gittutorial-2[7],
 699link:everyday.html[Everyday Git], linkgit:gitcvs-migration[7],
 700linkgit:gitglossary[7], linkgit:gitcore-tutorial[7],
 701linkgit:gitcli[7], link:user-manual.html[The Git User's Manual],
 702linkgit:gitworkflows[7]
 703
 704GIT
 705---
 706Part of the linkgit:git[1] suite