Documentation / git.txton commit Update jk/maint-strbuf-missing-init to builtin/ rename (03f94ae)
   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/git.html[documentation for release 1.7.0]
  47
  48* release notes for
  49  link:RelNotes-1.7.0.txt[1.7.0].
  50
  51* link:v1.6.6.2/git.html[documentation for release 1.6.6.2]
  52
  53* release notes for
  54  link:RelNotes-1.6.6.2.txt[1.6.6.2],
  55  link:RelNotes-1.6.6.1.txt[1.6.6.1],
  56  link:RelNotes-1.6.6.txt[1.6.6].
  57
  58* link:v1.6.5.8/git.html[documentation for release 1.6.5.8]
  59
  60* release notes for
  61  link:RelNotes-1.6.5.8.txt[1.6.5.8],
  62  link:RelNotes-1.6.5.7.txt[1.6.5.7],
  63  link:RelNotes-1.6.5.6.txt[1.6.5.6],
  64  link:RelNotes-1.6.5.5.txt[1.6.5.5],
  65  link:RelNotes-1.6.5.4.txt[1.6.5.4],
  66  link:RelNotes-1.6.5.3.txt[1.6.5.3],
  67  link:RelNotes-1.6.5.2.txt[1.6.5.2],
  68  link:RelNotes-1.6.5.1.txt[1.6.5.1],
  69  link:RelNotes-1.6.5.txt[1.6.5].
  70
  71* link:v1.6.4.4/git.html[documentation for release 1.6.4.4]
  72
  73* release notes for
  74  link:RelNotes-1.6.4.4.txt[1.6.4.4],
  75  link:RelNotes-1.6.4.3.txt[1.6.4.3],
  76  link:RelNotes-1.6.4.2.txt[1.6.4.2],
  77  link:RelNotes-1.6.4.1.txt[1.6.4.1],
  78  link:RelNotes-1.6.4.txt[1.6.4].
  79
  80* link:v1.6.3.4/git.html[documentation for release 1.6.3.4]
  81
  82* release notes for
  83  link:RelNotes-1.6.3.4.txt[1.6.3.4],
  84  link:RelNotes-1.6.3.3.txt[1.6.3.3],
  85  link:RelNotes-1.6.3.2.txt[1.6.3.2],
  86  link:RelNotes-1.6.3.1.txt[1.6.3.1],
  87  link:RelNotes-1.6.3.txt[1.6.3].
  88
  89* release notes for
  90  link:RelNotes-1.6.2.5.txt[1.6.2.5],
  91  link:RelNotes-1.6.2.4.txt[1.6.2.4],
  92  link:RelNotes-1.6.2.3.txt[1.6.2.3],
  93  link:RelNotes-1.6.2.2.txt[1.6.2.2],
  94  link:RelNotes-1.6.2.1.txt[1.6.2.1],
  95  link:RelNotes-1.6.2.txt[1.6.2].
  96
  97* link:v1.6.1.3/git.html[documentation for release 1.6.1.3]
  98
  99* release notes for
 100  link:RelNotes-1.6.1.3.txt[1.6.1.3],
 101  link:RelNotes-1.6.1.2.txt[1.6.1.2],
 102  link:RelNotes-1.6.1.1.txt[1.6.1.1],
 103  link:RelNotes-1.6.1.txt[1.6.1].
 104
 105* link:v1.6.0.6/git.html[documentation for release 1.6.0.6]
 106
 107* release notes for
 108  link:RelNotes-1.6.0.6.txt[1.6.0.6],
 109  link:RelNotes-1.6.0.5.txt[1.6.0.5],
 110  link:RelNotes-1.6.0.4.txt[1.6.0.4],
 111  link:RelNotes-1.6.0.3.txt[1.6.0.3],
 112  link:RelNotes-1.6.0.2.txt[1.6.0.2],
 113  link:RelNotes-1.6.0.1.txt[1.6.0.1],
 114  link:RelNotes-1.6.0.txt[1.6.0].
 115
 116* link:v1.5.6.6/git.html[documentation for release 1.5.6.6]
 117
 118* release notes for
 119  link:RelNotes-1.5.6.6.txt[1.5.6.6],
 120  link:RelNotes-1.5.6.5.txt[1.5.6.5],
 121  link:RelNotes-1.5.6.4.txt[1.5.6.4],
 122  link:RelNotes-1.5.6.3.txt[1.5.6.3],
 123  link:RelNotes-1.5.6.2.txt[1.5.6.2],
 124  link:RelNotes-1.5.6.1.txt[1.5.6.1],
 125  link:RelNotes-1.5.6.txt[1.5.6].
 126
 127* link:v1.5.5.6/git.html[documentation for release 1.5.5.6]
 128
 129* release notes for
 130  link:RelNotes-1.5.5.6.txt[1.5.5.6],
 131  link:RelNotes-1.5.5.5.txt[1.5.5.5],
 132  link:RelNotes-1.5.5.4.txt[1.5.5.4],
 133  link:RelNotes-1.5.5.3.txt[1.5.5.3],
 134  link:RelNotes-1.5.5.2.txt[1.5.5.2],
 135  link:RelNotes-1.5.5.1.txt[1.5.5.1],
 136  link:RelNotes-1.5.5.txt[1.5.5].
 137
 138* link:v1.5.4.7/git.html[documentation for release 1.5.4.7]
 139
 140* release notes for
 141  link:RelNotes-1.5.4.7.txt[1.5.4.7],
 142  link:RelNotes-1.5.4.6.txt[1.5.4.6],
 143  link:RelNotes-1.5.4.5.txt[1.5.4.5],
 144  link:RelNotes-1.5.4.4.txt[1.5.4.4],
 145  link:RelNotes-1.5.4.3.txt[1.5.4.3],
 146  link:RelNotes-1.5.4.2.txt[1.5.4.2],
 147  link:RelNotes-1.5.4.1.txt[1.5.4.1],
 148  link:RelNotes-1.5.4.txt[1.5.4].
 149
 150* link:v1.5.3.8/git.html[documentation for release 1.5.3.8]
 151
 152* release notes for
 153  link:RelNotes-1.5.3.8.txt[1.5.3.8],
 154  link:RelNotes-1.5.3.7.txt[1.5.3.7],
 155  link:RelNotes-1.5.3.6.txt[1.5.3.6],
 156  link:RelNotes-1.5.3.5.txt[1.5.3.5],
 157  link:RelNotes-1.5.3.4.txt[1.5.3.4],
 158  link:RelNotes-1.5.3.3.txt[1.5.3.3],
 159  link:RelNotes-1.5.3.2.txt[1.5.3.2],
 160  link:RelNotes-1.5.3.1.txt[1.5.3.1],
 161  link:RelNotes-1.5.3.txt[1.5.3].
 162
 163* link:v1.5.2.5/git.html[documentation for release 1.5.2.5]
 164
 165* release notes for
 166  link:RelNotes-1.5.2.5.txt[1.5.2.5],
 167  link:RelNotes-1.5.2.4.txt[1.5.2.4],
 168  link:RelNotes-1.5.2.3.txt[1.5.2.3],
 169  link:RelNotes-1.5.2.2.txt[1.5.2.2],
 170  link:RelNotes-1.5.2.1.txt[1.5.2.1],
 171  link:RelNotes-1.5.2.txt[1.5.2].
 172
 173* link:v1.5.1.6/git.html[documentation for release 1.5.1.6]
 174
 175* release notes for
 176  link:RelNotes-1.5.1.6.txt[1.5.1.6],
 177  link:RelNotes-1.5.1.5.txt[1.5.1.5],
 178  link:RelNotes-1.5.1.4.txt[1.5.1.4],
 179  link:RelNotes-1.5.1.3.txt[1.5.1.3],
 180  link:RelNotes-1.5.1.2.txt[1.5.1.2],
 181  link:RelNotes-1.5.1.1.txt[1.5.1.1],
 182  link:RelNotes-1.5.1.txt[1.5.1].
 183
 184* link:v1.5.0.7/git.html[documentation for release 1.5.0.7]
 185
 186* release notes for
 187  link:RelNotes-1.5.0.7.txt[1.5.0.7],
 188  link:RelNotes-1.5.0.6.txt[1.5.0.6],
 189  link:RelNotes-1.5.0.5.txt[1.5.0.5],
 190  link:RelNotes-1.5.0.3.txt[1.5.0.3],
 191  link:RelNotes-1.5.0.2.txt[1.5.0.2],
 192  link:RelNotes-1.5.0.1.txt[1.5.0.1],
 193  link:RelNotes-1.5.0.txt[1.5.0].
 194
 195* documentation for release link:v1.4.4.4/git.html[1.4.4.4],
 196  link:v1.3.3/git.html[1.3.3],
 197  link:v1.2.6/git.html[1.2.6],
 198  link:v1.0.13/git.html[1.0.13].
 199
 200============
 201
 202endif::stalenotes[]
 203
 204OPTIONS
 205-------
 206--version::
 207        Prints the git suite version that the 'git' program came from.
 208
 209--help::
 210        Prints the synopsis and a list of the most commonly used
 211        commands. If the option '--all' or '-a' is given then all
 212        available commands are printed. If a git command is named this
 213        option will bring up the manual page for that command.
 214+
 215Other options are available to control how the manual page is
 216displayed. See linkgit:git-help[1] for more information,
 217because `git --help ...` is converted internally into `git
 218help ...`.
 219
 220--exec-path::
 221        Path to wherever your core git programs are installed.
 222        This can also be controlled by setting the GIT_EXEC_PATH
 223        environment variable. If no path is given, 'git' will print
 224        the current setting and then exit.
 225
 226--html-path::
 227        Print the path to wherever your git HTML documentation is installed
 228        and exit.
 229
 230-p::
 231--paginate::
 232        Pipe all output into 'less' (or if set, $PAGER).
 233
 234--no-pager::
 235        Do not pipe git output into a pager.
 236
 237--git-dir=<path>::
 238        Set the path to the repository. This can also be controlled by
 239        setting the GIT_DIR environment variable. It can be an absolute
 240        path or relative path to current working directory.
 241
 242--work-tree=<path>::
 243        Set the path to the working tree.  The value will not be
 244        used in combination with repositories found automatically in
 245        a .git directory (i.e. $GIT_DIR is not set).
 246        This can also be controlled by setting the GIT_WORK_TREE
 247        environment variable and the core.worktree configuration
 248        variable. It can be an absolute path or relative path to
 249        the directory specified by --git-dir or GIT_DIR.
 250        Note: If --git-dir or GIT_DIR are specified but none of
 251        --work-tree, GIT_WORK_TREE and core.worktree is specified,
 252        the current working directory is regarded as the top directory
 253        of your working tree.
 254
 255--bare::
 256        Treat the repository as a bare repository.  If GIT_DIR
 257        environment is not set, it is set to the current working
 258        directory.
 259
 260--no-replace-objects::
 261        Do not use replacement refs to replace git objects. See
 262        linkgit:git-replace[1] for more information.
 263
 264
 265FURTHER DOCUMENTATION
 266---------------------
 267
 268See the references above to get started using git.  The following is
 269probably more detail than necessary for a first-time user.
 270
 271The link:user-manual.html#git-concepts[git concepts chapter of the
 272user-manual] and linkgit:gitcore-tutorial[7] both provide
 273introductions to the underlying git architecture.
 274
 275See linkgit:gitworkflows[7] for an overview of recommended workflows.
 276
 277See also the link:howto-index.html[howto] documents for some useful
 278examples.
 279
 280The internals are documented in the
 281link:technical/api-index.html[GIT API documentation].
 282
 283GIT COMMANDS
 284------------
 285
 286We divide git into high level ("porcelain") commands and low level
 287("plumbing") commands.
 288
 289High-level commands (porcelain)
 290-------------------------------
 291
 292We separate the porcelain commands into the main commands and some
 293ancillary user utilities.
 294
 295Main porcelain commands
 296~~~~~~~~~~~~~~~~~~~~~~~
 297
 298include::cmds-mainporcelain.txt[]
 299
 300Ancillary Commands
 301~~~~~~~~~~~~~~~~~~
 302Manipulators:
 303
 304include::cmds-ancillarymanipulators.txt[]
 305
 306Interrogators:
 307
 308include::cmds-ancillaryinterrogators.txt[]
 309
 310
 311Interacting with Others
 312~~~~~~~~~~~~~~~~~~~~~~~
 313
 314These commands are to interact with foreign SCM and with other
 315people via patch over e-mail.
 316
 317include::cmds-foreignscminterface.txt[]
 318
 319
 320Low-level commands (plumbing)
 321-----------------------------
 322
 323Although git includes its
 324own porcelain layer, its low-level commands are sufficient to support
 325development of alternative porcelains.  Developers of such porcelains
 326might start by reading about linkgit:git-update-index[1] and
 327linkgit:git-read-tree[1].
 328
 329The interface (input, output, set of options and the semantics)
 330to these low-level commands are meant to be a lot more stable
 331than Porcelain level commands, because these commands are
 332primarily for scripted use.  The interface to Porcelain commands
 333on the other hand are subject to change in order to improve the
 334end user experience.
 335
 336The following description divides
 337the low-level commands into commands that manipulate objects (in
 338the repository, index, and working tree), commands that interrogate and
 339compare objects, and commands that move objects and references between
 340repositories.
 341
 342
 343Manipulation commands
 344~~~~~~~~~~~~~~~~~~~~~
 345
 346include::cmds-plumbingmanipulators.txt[]
 347
 348
 349Interrogation commands
 350~~~~~~~~~~~~~~~~~~~~~~
 351
 352include::cmds-plumbinginterrogators.txt[]
 353
 354In general, the interrogate commands do not touch the files in
 355the working tree.
 356
 357
 358Synching repositories
 359~~~~~~~~~~~~~~~~~~~~~
 360
 361include::cmds-synchingrepositories.txt[]
 362
 363The following are helper commands used by the above; end users
 364typically do not use them directly.
 365
 366include::cmds-synchelpers.txt[]
 367
 368
 369Internal helper commands
 370~~~~~~~~~~~~~~~~~~~~~~~~
 371
 372These are internal helper commands used by other commands; end
 373users typically do not use them directly.
 374
 375include::cmds-purehelpers.txt[]
 376
 377
 378Configuration Mechanism
 379-----------------------
 380
 381Starting from 0.99.9 (actually mid 0.99.8.GIT), `.git/config` file
 382is used to hold per-repository configuration options.  It is a
 383simple text file modeled after `.ini` format familiar to some
 384people.  Here is an example:
 385
 386------------
 387#
 388# A '#' or ';' character indicates a comment.
 389#
 390
 391; core variables
 392[core]
 393        ; Don't trust file modes
 394        filemode = false
 395
 396; user identity
 397[user]
 398        name = "Junio C Hamano"
 399        email = "junkio@twinsun.com"
 400
 401------------
 402
 403Various commands read from the configuration file and adjust
 404their operation accordingly.
 405
 406
 407Identifier Terminology
 408----------------------
 409<object>::
 410        Indicates the object name for any type of object.
 411
 412<blob>::
 413        Indicates a blob object name.
 414
 415<tree>::
 416        Indicates a tree object name.
 417
 418<commit>::
 419        Indicates a commit object name.
 420
 421<tree-ish>::
 422        Indicates a tree, commit or tag object name.  A
 423        command that takes a <tree-ish> argument ultimately wants to
 424        operate on a <tree> object but automatically dereferences
 425        <commit> and <tag> objects that point at a <tree>.
 426
 427<commit-ish>::
 428        Indicates a commit or tag object name.  A
 429        command that takes a <commit-ish> argument ultimately wants to
 430        operate on a <commit> object but automatically dereferences
 431        <tag> objects that point at a <commit>.
 432
 433<type>::
 434        Indicates that an object type is required.
 435        Currently one of: `blob`, `tree`, `commit`, or `tag`.
 436
 437<file>::
 438        Indicates a filename - almost always relative to the
 439        root of the tree structure `GIT_INDEX_FILE` describes.
 440
 441Symbolic Identifiers
 442--------------------
 443Any git command accepting any <object> can also use the following
 444symbolic notation:
 445
 446HEAD::
 447        indicates the head of the current branch (i.e. the
 448        contents of `$GIT_DIR/HEAD`).
 449
 450<tag>::
 451        a valid tag 'name'
 452        (i.e. the contents of `$GIT_DIR/refs/tags/<tag>`).
 453
 454<head>::
 455        a valid head 'name'
 456        (i.e. the contents of `$GIT_DIR/refs/heads/<head>`).
 457
 458For a more complete list of ways to spell object names, see
 459"SPECIFYING REVISIONS" section in linkgit:git-rev-parse[1].
 460
 461
 462File/Directory Structure
 463------------------------
 464
 465Please see the linkgit:gitrepository-layout[5] document.
 466
 467Read linkgit:githooks[5] for more details about each hook.
 468
 469Higher level SCMs may provide and manage additional information in the
 470`$GIT_DIR`.
 471
 472
 473Terminology
 474-----------
 475Please see linkgit:gitglossary[7].
 476
 477
 478Environment Variables
 479---------------------
 480Various git commands use the following environment variables:
 481
 482The git Repository
 483~~~~~~~~~~~~~~~~~~
 484These environment variables apply to 'all' core git commands. Nb: it
 485is worth noting that they may be used/overridden by SCMS sitting above
 486git so take care if using Cogito etc.
 487
 488'GIT_INDEX_FILE'::
 489        This environment allows the specification of an alternate
 490        index file. If not specified, the default of `$GIT_DIR/index`
 491        is used.
 492
 493'GIT_OBJECT_DIRECTORY'::
 494        If the object storage directory is specified via this
 495        environment variable then the sha1 directories are created
 496        underneath - otherwise the default `$GIT_DIR/objects`
 497        directory is used.
 498
 499'GIT_ALTERNATE_OBJECT_DIRECTORIES'::
 500        Due to the immutable nature of git objects, old objects can be
 501        archived into shared, read-only directories. This variable
 502        specifies a ":" separated (on Windows ";" separated) list
 503        of git object directories which can be used to search for git
 504        objects. New objects will not be written to these directories.
 505
 506'GIT_DIR'::
 507        If the 'GIT_DIR' environment variable is set then it
 508        specifies a path to use instead of the default `.git`
 509        for the base of the repository.
 510
 511'GIT_WORK_TREE'::
 512        Set the path to the working tree.  The value will not be
 513        used in combination with repositories found automatically in
 514        a .git directory (i.e. $GIT_DIR is not set).
 515        This can also be controlled by the '--work-tree' command line
 516        option and the core.worktree configuration variable.
 517
 518'GIT_CEILING_DIRECTORIES'::
 519        This should be a colon-separated list of absolute paths.
 520        If set, it is a list of directories that git should not chdir
 521        up into while looking for a repository directory.
 522        It will not exclude the current working directory or
 523        a GIT_DIR set on the command line or in the environment.
 524        (Useful for excluding slow-loading network directories.)
 525
 526git Commits
 527~~~~~~~~~~~
 528'GIT_AUTHOR_NAME'::
 529'GIT_AUTHOR_EMAIL'::
 530'GIT_AUTHOR_DATE'::
 531'GIT_COMMITTER_NAME'::
 532'GIT_COMMITTER_EMAIL'::
 533'GIT_COMMITTER_DATE'::
 534'EMAIL'::
 535        see linkgit:git-commit-tree[1]
 536
 537git Diffs
 538~~~~~~~~~
 539'GIT_DIFF_OPTS'::
 540        Only valid setting is "--unified=??" or "-u??" to set the
 541        number of context lines shown when a unified diff is created.
 542        This takes precedence over any "-U" or "--unified" option
 543        value passed on the git diff command line.
 544
 545'GIT_EXTERNAL_DIFF'::
 546        When the environment variable 'GIT_EXTERNAL_DIFF' is set, the
 547        program named by it is called, instead of the diff invocation
 548        described above.  For a path that is added, removed, or modified,
 549        'GIT_EXTERNAL_DIFF' is called with 7 parameters:
 550
 551        path old-file old-hex old-mode new-file new-hex new-mode
 552+
 553where:
 554
 555        <old|new>-file:: are files GIT_EXTERNAL_DIFF can use to read the
 556                         contents of <old|new>,
 557        <old|new>-hex:: are the 40-hexdigit SHA1 hashes,
 558        <old|new>-mode:: are the octal representation of the file modes.
 559
 560+
 561The file parameters can point at the user's working file
 562(e.g. `new-file` in "git-diff-files"), `/dev/null` (e.g. `old-file`
 563when a new file is added), or a temporary file (e.g. `old-file` in the
 564index).  'GIT_EXTERNAL_DIFF' should not worry about unlinking the
 565temporary file --- it is removed when 'GIT_EXTERNAL_DIFF' exits.
 566+
 567For a path that is unmerged, 'GIT_EXTERNAL_DIFF' is called with 1
 568parameter, <path>.
 569
 570other
 571~~~~~
 572'GIT_MERGE_VERBOSITY'::
 573        A number controlling the amount of output shown by
 574        the recursive merge strategy.  Overrides merge.verbosity.
 575        See linkgit:git-merge[1]
 576
 577'GIT_PAGER'::
 578        This environment variable overrides `$PAGER`. If it is set
 579        to an empty string or to the value "cat", git will not launch
 580        a pager.  See also the `core.pager` option in
 581        linkgit:git-config[1].
 582
 583'GIT_SSH'::
 584        If this environment variable is set then 'git fetch'
 585        and 'git push' will use this command instead
 586        of 'ssh' when they need to connect to a remote system.
 587        The '$GIT_SSH' command will be given exactly two arguments:
 588        the 'username@host' (or just 'host') from the URL and the
 589        shell command to execute on that remote system.
 590+
 591To pass options to the program that you want to list in GIT_SSH
 592you will need to wrap the program and options into a shell script,
 593then set GIT_SSH to refer to the shell script.
 594+
 595Usually it is easier to configure any desired options through your
 596personal `.ssh/config` file.  Please consult your ssh documentation
 597for further details.
 598
 599'GIT_FLUSH'::
 600        If this environment variable is set to "1", then commands such
 601        as 'git blame' (in incremental mode), 'git rev-list', 'git log',
 602        and 'git whatchanged' will force a flush of the output stream
 603        after each commit-oriented record have been flushed.   If this
 604        variable is set to "0", the output of these commands will be done
 605        using completely buffered I/O.   If this environment variable is
 606        not set, git will choose buffered or record-oriented flushing
 607        based on whether stdout appears to be redirected to a file or not.
 608
 609'GIT_TRACE'::
 610        If this variable is set to "1", "2" or "true" (comparison
 611        is case insensitive), git will print `trace:` messages on
 612        stderr telling about alias expansion, built-in command
 613        execution and external command execution.
 614        If this variable is set to an integer value greater than 1
 615        and lower than 10 (strictly) then git will interpret this
 616        value as an open file descriptor and will try to write the
 617        trace messages into this file descriptor.
 618        Alternatively, if this variable is set to an absolute path
 619        (starting with a '/' character), git will interpret this
 620        as a file path and will try to write the trace messages
 621        into it.
 622
 623Discussion[[Discussion]]
 624------------------------
 625
 626More detail on the following is available from the
 627link:user-manual.html#git-concepts[git concepts chapter of the
 628user-manual] and linkgit:gitcore-tutorial[7].
 629
 630A git project normally consists of a working directory with a ".git"
 631subdirectory at the top level.  The .git directory contains, among other
 632things, a compressed object database representing the complete history
 633of the project, an "index" file which links that history to the current
 634contents of the working tree, and named pointers into that history such
 635as tags and branch heads.
 636
 637The object database contains objects of three main types: blobs, which
 638hold file data; trees, which point to blobs and other trees to build up
 639directory hierarchies; and commits, which each reference a single tree
 640and some number of parent commits.
 641
 642The commit, equivalent to what other systems call a "changeset" or
 643"version", represents a step in the project's history, and each parent
 644represents an immediately preceding step.  Commits with more than one
 645parent represent merges of independent lines of development.
 646
 647All objects are named by the SHA1 hash of their contents, normally
 648written as a string of 40 hex digits.  Such names are globally unique.
 649The entire history leading up to a commit can be vouched for by signing
 650just that commit.  A fourth object type, the tag, is provided for this
 651purpose.
 652
 653When first created, objects are stored in individual files, but for
 654efficiency may later be compressed together into "pack files".
 655
 656Named pointers called refs mark interesting points in history.  A ref
 657may contain the SHA1 name of an object or the name of another ref.  Refs
 658with names beginning `ref/head/` contain the SHA1 name of the most
 659recent commit (or "head") of a branch under development.  SHA1 names of
 660tags of interest are stored under `ref/tags/`.  A special ref named
 661`HEAD` contains the name of the currently checked-out branch.
 662
 663The index file is initialized with a list of all paths and, for each
 664path, a blob object and a set of attributes.  The blob object represents
 665the contents of the file as of the head of the current branch.  The
 666attributes (last modified time, size, etc.) are taken from the
 667corresponding file in the working tree.  Subsequent changes to the
 668working tree can be found by comparing these attributes.  The index may
 669be updated with new content, and new commits may be created from the
 670content stored in the index.
 671
 672The index is also capable of storing multiple entries (called "stages")
 673for a given pathname.  These stages are used to hold the various
 674unmerged version of a file when a merge is in progress.
 675
 676Authors
 677-------
 678* git's founding father is Linus Torvalds <torvalds@osdl.org>.
 679* The current git nurse is Junio C Hamano <gitster@pobox.com>.
 680* The git potty was written by Andreas Ericsson <ae@op5.se>.
 681* General upbringing is handled by the git-list <git@vger.kernel.org>.
 682
 683Documentation
 684--------------
 685The documentation for git suite was started by David Greaves
 686<david@dgreaves.com>, and later enhanced greatly by the
 687contributors on the git-list <git@vger.kernel.org>.
 688
 689SEE ALSO
 690--------
 691linkgit:gittutorial[7], linkgit:gittutorial-2[7],
 692link:everyday.html[Everyday Git], linkgit:gitcvs-migration[7],
 693linkgit:gitglossary[7], linkgit:gitcore-tutorial[7],
 694linkgit:gitcli[7], link:user-manual.html[The Git User's Manual],
 695linkgit:gitworkflows[7]
 696
 697GIT
 698---
 699Part of the linkgit:git[1] suite