Documentation / git.txton commit Merge branch 'js/filter-branch-prime' (f012d27)
   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:v1.6.6/git.html[documentation for release 1.6.6]
  47
  48* release notes for
  49  link:RelNotes-1.6.6.txt[1.6.6].
  50
  51* link:v1.6.5.7/git.html[documentation for release 1.6.5.7]
  52
  53* release notes for
  54  link:RelNotes-1.6.5.7.txt[1.6.5.7],
  55  link:RelNotes-1.6.5.6.txt[1.6.5.6],
  56  link:RelNotes-1.6.5.5.txt[1.6.5.5],
  57  link:RelNotes-1.6.5.4.txt[1.6.5.4],
  58  link:RelNotes-1.6.5.3.txt[1.6.5.3],
  59  link:RelNotes-1.6.5.2.txt[1.6.5.2],
  60  link:RelNotes-1.6.5.1.txt[1.6.5.1],
  61  link:RelNotes-1.6.5.txt[1.6.5].
  62
  63* link:v1.6.4.4/git.html[documentation for release 1.6.4.4]
  64
  65* release notes for
  66  link:RelNotes-1.6.4.4.txt[1.6.4.4],
  67  link:RelNotes-1.6.4.3.txt[1.6.4.3],
  68  link:RelNotes-1.6.4.2.txt[1.6.4.2],
  69  link:RelNotes-1.6.4.1.txt[1.6.4.1],
  70  link:RelNotes-1.6.4.txt[1.6.4].
  71
  72* link:v1.6.3.4/git.html[documentation for release 1.6.3.4]
  73
  74* release notes for
  75  link:RelNotes-1.6.3.4.txt[1.6.3.4],
  76  link:RelNotes-1.6.3.3.txt[1.6.3.3],
  77  link:RelNotes-1.6.3.2.txt[1.6.3.2],
  78  link:RelNotes-1.6.3.1.txt[1.6.3.1],
  79  link:RelNotes-1.6.3.txt[1.6.3].
  80
  81* release notes for
  82  link:RelNotes-1.6.2.5.txt[1.6.2.5],
  83  link:RelNotes-1.6.2.4.txt[1.6.2.4],
  84  link:RelNotes-1.6.2.3.txt[1.6.2.3],
  85  link:RelNotes-1.6.2.2.txt[1.6.2.2],
  86  link:RelNotes-1.6.2.1.txt[1.6.2.1],
  87  link:RelNotes-1.6.2.txt[1.6.2].
  88
  89* link:v1.6.1.3/git.html[documentation for release 1.6.1.3]
  90
  91* release notes for
  92  link:RelNotes-1.6.1.3.txt[1.6.1.3],
  93  link:RelNotes-1.6.1.2.txt[1.6.1.2],
  94  link:RelNotes-1.6.1.1.txt[1.6.1.1],
  95  link:RelNotes-1.6.1.txt[1.6.1].
  96
  97* link:v1.6.0.6/git.html[documentation for release 1.6.0.6]
  98
  99* release notes for
 100  link:RelNotes-1.6.0.6.txt[1.6.0.6],
 101  link:RelNotes-1.6.0.5.txt[1.6.0.5],
 102  link:RelNotes-1.6.0.4.txt[1.6.0.4],
 103  link:RelNotes-1.6.0.3.txt[1.6.0.3],
 104  link:RelNotes-1.6.0.2.txt[1.6.0.2],
 105  link:RelNotes-1.6.0.1.txt[1.6.0.1],
 106  link:RelNotes-1.6.0.txt[1.6.0].
 107
 108* link:v1.5.6.6/git.html[documentation for release 1.5.6.6]
 109
 110* release notes for
 111  link:RelNotes-1.5.6.6.txt[1.5.6.6],
 112  link:RelNotes-1.5.6.5.txt[1.5.6.5],
 113  link:RelNotes-1.5.6.4.txt[1.5.6.4],
 114  link:RelNotes-1.5.6.3.txt[1.5.6.3],
 115  link:RelNotes-1.5.6.2.txt[1.5.6.2],
 116  link:RelNotes-1.5.6.1.txt[1.5.6.1],
 117  link:RelNotes-1.5.6.txt[1.5.6].
 118
 119* link:v1.5.5.6/git.html[documentation for release 1.5.5.6]
 120
 121* release notes for
 122  link:RelNotes-1.5.5.6.txt[1.5.5.6],
 123  link:RelNotes-1.5.5.5.txt[1.5.5.5],
 124  link:RelNotes-1.5.5.4.txt[1.5.5.4],
 125  link:RelNotes-1.5.5.3.txt[1.5.5.3],
 126  link:RelNotes-1.5.5.2.txt[1.5.5.2],
 127  link:RelNotes-1.5.5.1.txt[1.5.5.1],
 128  link:RelNotes-1.5.5.txt[1.5.5].
 129
 130* link:v1.5.4.7/git.html[documentation for release 1.5.4.7]
 131
 132* release notes for
 133  link:RelNotes-1.5.4.7.txt[1.5.4.7],
 134  link:RelNotes-1.5.4.6.txt[1.5.4.6],
 135  link:RelNotes-1.5.4.5.txt[1.5.4.5],
 136  link:RelNotes-1.5.4.4.txt[1.5.4.4],
 137  link:RelNotes-1.5.4.3.txt[1.5.4.3],
 138  link:RelNotes-1.5.4.2.txt[1.5.4.2],
 139  link:RelNotes-1.5.4.1.txt[1.5.4.1],
 140  link:RelNotes-1.5.4.txt[1.5.4].
 141
 142* link:v1.5.3.8/git.html[documentation for release 1.5.3.8]
 143
 144* release notes for
 145  link:RelNotes-1.5.3.8.txt[1.5.3.8],
 146  link:RelNotes-1.5.3.7.txt[1.5.3.7],
 147  link:RelNotes-1.5.3.6.txt[1.5.3.6],
 148  link:RelNotes-1.5.3.5.txt[1.5.3.5],
 149  link:RelNotes-1.5.3.4.txt[1.5.3.4],
 150  link:RelNotes-1.5.3.3.txt[1.5.3.3],
 151  link:RelNotes-1.5.3.2.txt[1.5.3.2],
 152  link:RelNotes-1.5.3.1.txt[1.5.3.1],
 153  link:RelNotes-1.5.3.txt[1.5.3].
 154
 155* link:v1.5.2.5/git.html[documentation for release 1.5.2.5]
 156
 157* release notes for
 158  link:RelNotes-1.5.2.5.txt[1.5.2.5],
 159  link:RelNotes-1.5.2.4.txt[1.5.2.4],
 160  link:RelNotes-1.5.2.3.txt[1.5.2.3],
 161  link:RelNotes-1.5.2.2.txt[1.5.2.2],
 162  link:RelNotes-1.5.2.1.txt[1.5.2.1],
 163  link:RelNotes-1.5.2.txt[1.5.2].
 164
 165* link:v1.5.1.6/git.html[documentation for release 1.5.1.6]
 166
 167* release notes for
 168  link:RelNotes-1.5.1.6.txt[1.5.1.6],
 169  link:RelNotes-1.5.1.5.txt[1.5.1.5],
 170  link:RelNotes-1.5.1.4.txt[1.5.1.4],
 171  link:RelNotes-1.5.1.3.txt[1.5.1.3],
 172  link:RelNotes-1.5.1.2.txt[1.5.1.2],
 173  link:RelNotes-1.5.1.1.txt[1.5.1.1],
 174  link:RelNotes-1.5.1.txt[1.5.1].
 175
 176* link:v1.5.0.7/git.html[documentation for release 1.5.0.7]
 177
 178* release notes for
 179  link:RelNotes-1.5.0.7.txt[1.5.0.7],
 180  link:RelNotes-1.5.0.6.txt[1.5.0.6],
 181  link:RelNotes-1.5.0.5.txt[1.5.0.5],
 182  link:RelNotes-1.5.0.3.txt[1.5.0.3],
 183  link:RelNotes-1.5.0.2.txt[1.5.0.2],
 184  link:RelNotes-1.5.0.1.txt[1.5.0.1],
 185  link:RelNotes-1.5.0.txt[1.5.0].
 186
 187* documentation for release link:v1.4.4.4/git.html[1.4.4.4],
 188  link:v1.3.3/git.html[1.3.3],
 189  link:v1.2.6/git.html[1.2.6],
 190  link:v1.0.13/git.html[1.0.13].
 191
 192============
 193
 194endif::stalenotes[]
 195
 196OPTIONS
 197-------
 198--version::
 199        Prints the git suite version that the 'git' program came from.
 200
 201--help::
 202        Prints the synopsis and a list of the most commonly used
 203        commands. If the option '--all' or '-a' is given then all
 204        available commands are printed. If a git command is named this
 205        option will bring up the manual page for that command.
 206+
 207Other options are available to control how the manual page is
 208displayed. See linkgit:git-help[1] for more information,
 209because `git --help ...` is converted internally into `git
 210help ...`.
 211
 212--exec-path::
 213        Path to wherever your core git programs are installed.
 214        This can also be controlled by setting the GIT_EXEC_PATH
 215        environment variable. If no path is given, 'git' will print
 216        the current setting and then exit.
 217
 218--html-path::
 219        Print the path to wherever your git HTML documentation is installed
 220        and exit.
 221
 222-p::
 223--paginate::
 224        Pipe all output into 'less' (or if set, $PAGER).
 225
 226--no-pager::
 227        Do not pipe git output into a pager.
 228
 229--git-dir=<path>::
 230        Set the path to the repository. This can also be controlled by
 231        setting the GIT_DIR environment variable. It can be an absolute
 232        path or relative path to current working directory.
 233
 234--work-tree=<path>::
 235        Set the path to the working tree.  The value will not be
 236        used in combination with repositories found automatically in
 237        a .git directory (i.e. $GIT_DIR is not set).
 238        This can also be controlled by setting the GIT_WORK_TREE
 239        environment variable and the core.worktree configuration
 240        variable. It can be an absolute path or relative path to
 241        the directory specified by --git-dir or GIT_DIR.
 242        Note: If --git-dir or GIT_DIR are specified but none of
 243        --work-tree, GIT_WORK_TREE and core.worktree is specified,
 244        the current working directory is regarded as the top directory
 245        of your working tree.
 246
 247--bare::
 248        Treat the repository as a bare repository.  If GIT_DIR
 249        environment is not set, it is set to the current working
 250        directory.
 251
 252--no-replace-objects::
 253        Do not use replacement refs to replace git objects. See
 254        linkgit:git-replace[1] for more information.
 255
 256
 257FURTHER DOCUMENTATION
 258---------------------
 259
 260See the references above to get started using git.  The following is
 261probably more detail than necessary for a first-time user.
 262
 263The link:user-manual.html#git-concepts[git concepts chapter of the
 264user-manual] and linkgit:gitcore-tutorial[7] both provide
 265introductions to the underlying git architecture.
 266
 267See linkgit:gitworkflows[7] for an overview of recommended workflows.
 268
 269See also the link:howto-index.html[howto] documents for some useful
 270examples.
 271
 272The internals are documented in the
 273link:technical/api-index.html[GIT API documentation].
 274
 275GIT COMMANDS
 276------------
 277
 278We divide git into high level ("porcelain") commands and low level
 279("plumbing") commands.
 280
 281High-level commands (porcelain)
 282-------------------------------
 283
 284We separate the porcelain commands into the main commands and some
 285ancillary user utilities.
 286
 287Main porcelain commands
 288~~~~~~~~~~~~~~~~~~~~~~~
 289
 290include::cmds-mainporcelain.txt[]
 291
 292Ancillary Commands
 293~~~~~~~~~~~~~~~~~~
 294Manipulators:
 295
 296include::cmds-ancillarymanipulators.txt[]
 297
 298Interrogators:
 299
 300include::cmds-ancillaryinterrogators.txt[]
 301
 302
 303Interacting with Others
 304~~~~~~~~~~~~~~~~~~~~~~~
 305
 306These commands are to interact with foreign SCM and with other
 307people via patch over e-mail.
 308
 309include::cmds-foreignscminterface.txt[]
 310
 311
 312Low-level commands (plumbing)
 313-----------------------------
 314
 315Although git includes its
 316own porcelain layer, its low-level commands are sufficient to support
 317development of alternative porcelains.  Developers of such porcelains
 318might start by reading about linkgit:git-update-index[1] and
 319linkgit:git-read-tree[1].
 320
 321The interface (input, output, set of options and the semantics)
 322to these low-level commands are meant to be a lot more stable
 323than Porcelain level commands, because these commands are
 324primarily for scripted use.  The interface to Porcelain commands
 325on the other hand are subject to change in order to improve the
 326end user experience.
 327
 328The following description divides
 329the low-level commands into commands that manipulate objects (in
 330the repository, index, and working tree), commands that interrogate and
 331compare objects, and commands that move objects and references between
 332repositories.
 333
 334
 335Manipulation commands
 336~~~~~~~~~~~~~~~~~~~~~
 337
 338include::cmds-plumbingmanipulators.txt[]
 339
 340
 341Interrogation commands
 342~~~~~~~~~~~~~~~~~~~~~~
 343
 344include::cmds-plumbinginterrogators.txt[]
 345
 346In general, the interrogate commands do not touch the files in
 347the working tree.
 348
 349
 350Synching repositories
 351~~~~~~~~~~~~~~~~~~~~~
 352
 353include::cmds-synchingrepositories.txt[]
 354
 355The following are helper commands used by the above; end users
 356typically do not use them directly.
 357
 358include::cmds-synchelpers.txt[]
 359
 360
 361Internal helper commands
 362~~~~~~~~~~~~~~~~~~~~~~~~
 363
 364These are internal helper commands used by other commands; end
 365users typically do not use them directly.
 366
 367include::cmds-purehelpers.txt[]
 368
 369
 370Configuration Mechanism
 371-----------------------
 372
 373Starting from 0.99.9 (actually mid 0.99.8.GIT), `.git/config` file
 374is used to hold per-repository configuration options.  It is a
 375simple text file modeled after `.ini` format familiar to some
 376people.  Here is an example:
 377
 378------------
 379#
 380# A '#' or ';' character indicates a comment.
 381#
 382
 383; core variables
 384[core]
 385        ; Don't trust file modes
 386        filemode = false
 387
 388; user identity
 389[user]
 390        name = "Junio C Hamano"
 391        email = "junkio@twinsun.com"
 392
 393------------
 394
 395Various commands read from the configuration file and adjust
 396their operation accordingly.
 397
 398
 399Identifier Terminology
 400----------------------
 401<object>::
 402        Indicates the object name for any type of object.
 403
 404<blob>::
 405        Indicates a blob object name.
 406
 407<tree>::
 408        Indicates a tree object name.
 409
 410<commit>::
 411        Indicates a commit object name.
 412
 413<tree-ish>::
 414        Indicates a tree, commit or tag object name.  A
 415        command that takes a <tree-ish> argument ultimately wants to
 416        operate on a <tree> object but automatically dereferences
 417        <commit> and <tag> objects that point at a <tree>.
 418
 419<commit-ish>::
 420        Indicates a commit or tag object name.  A
 421        command that takes a <commit-ish> argument ultimately wants to
 422        operate on a <commit> object but automatically dereferences
 423        <tag> objects that point at a <commit>.
 424
 425<type>::
 426        Indicates that an object type is required.
 427        Currently one of: `blob`, `tree`, `commit`, or `tag`.
 428
 429<file>::
 430        Indicates a filename - almost always relative to the
 431        root of the tree structure `GIT_INDEX_FILE` describes.
 432
 433Symbolic Identifiers
 434--------------------
 435Any git command accepting any <object> can also use the following
 436symbolic notation:
 437
 438HEAD::
 439        indicates the head of the current branch (i.e. the
 440        contents of `$GIT_DIR/HEAD`).
 441
 442<tag>::
 443        a valid tag 'name'
 444        (i.e. the contents of `$GIT_DIR/refs/tags/<tag>`).
 445
 446<head>::
 447        a valid head 'name'
 448        (i.e. the contents of `$GIT_DIR/refs/heads/<head>`).
 449
 450For a more complete list of ways to spell object names, see
 451"SPECIFYING REVISIONS" section in linkgit:git-rev-parse[1].
 452
 453
 454File/Directory Structure
 455------------------------
 456
 457Please see the linkgit:gitrepository-layout[5] document.
 458
 459Read linkgit:githooks[5] for more details about each hook.
 460
 461Higher level SCMs may provide and manage additional information in the
 462`$GIT_DIR`.
 463
 464
 465Terminology
 466-----------
 467Please see linkgit:gitglossary[7].
 468
 469
 470Environment Variables
 471---------------------
 472Various git commands use the following environment variables:
 473
 474The git Repository
 475~~~~~~~~~~~~~~~~~~
 476These environment variables apply to 'all' core git commands. Nb: it
 477is worth noting that they may be used/overridden by SCMS sitting above
 478git so take care if using Cogito etc.
 479
 480'GIT_INDEX_FILE'::
 481        This environment allows the specification of an alternate
 482        index file. If not specified, the default of `$GIT_DIR/index`
 483        is used.
 484
 485'GIT_OBJECT_DIRECTORY'::
 486        If the object storage directory is specified via this
 487        environment variable then the sha1 directories are created
 488        underneath - otherwise the default `$GIT_DIR/objects`
 489        directory is used.
 490
 491'GIT_ALTERNATE_OBJECT_DIRECTORIES'::
 492        Due to the immutable nature of git objects, old objects can be
 493        archived into shared, read-only directories. This variable
 494        specifies a ":" separated (on Windows ";" separated) list
 495        of git object directories which can be used to search for git
 496        objects. New objects will not be written to these directories.
 497
 498'GIT_DIR'::
 499        If the 'GIT_DIR' environment variable is set then it
 500        specifies a path to use instead of the default `.git`
 501        for the base of the repository.
 502
 503'GIT_WORK_TREE'::
 504        Set the path to the working tree.  The value will not be
 505        used in combination with repositories found automatically in
 506        a .git directory (i.e. $GIT_DIR is not set).
 507        This can also be controlled by the '--work-tree' command line
 508        option and the core.worktree configuration variable.
 509
 510'GIT_CEILING_DIRECTORIES'::
 511        This should be a colon-separated list of absolute paths.
 512        If set, it is a list of directories that git should not chdir
 513        up into while looking for a repository directory.
 514        It will not exclude the current working directory or
 515        a GIT_DIR set on the command line or in the environment.
 516        (Useful for excluding slow-loading network directories.)
 517
 518git Commits
 519~~~~~~~~~~~
 520'GIT_AUTHOR_NAME'::
 521'GIT_AUTHOR_EMAIL'::
 522'GIT_AUTHOR_DATE'::
 523'GIT_COMMITTER_NAME'::
 524'GIT_COMMITTER_EMAIL'::
 525'GIT_COMMITTER_DATE'::
 526'EMAIL'::
 527        see linkgit:git-commit-tree[1]
 528
 529git Diffs
 530~~~~~~~~~
 531'GIT_DIFF_OPTS'::
 532        Only valid setting is "--unified=??" or "-u??" to set the
 533        number of context lines shown when a unified diff is created.
 534        This takes precedence over any "-U" or "--unified" option
 535        value passed on the git diff command line.
 536
 537'GIT_EXTERNAL_DIFF'::
 538        When the environment variable 'GIT_EXTERNAL_DIFF' is set, the
 539        program named by it is called, instead of the diff invocation
 540        described above.  For a path that is added, removed, or modified,
 541        'GIT_EXTERNAL_DIFF' is called with 7 parameters:
 542
 543        path old-file old-hex old-mode new-file new-hex new-mode
 544+
 545where:
 546
 547        <old|new>-file:: are files GIT_EXTERNAL_DIFF can use to read the
 548                         contents of <old|new>,
 549        <old|new>-hex:: are the 40-hexdigit SHA1 hashes,
 550        <old|new>-mode:: are the octal representation of the file modes.
 551
 552+
 553The file parameters can point at the user's working file
 554(e.g. `new-file` in "git-diff-files"), `/dev/null` (e.g. `old-file`
 555when a new file is added), or a temporary file (e.g. `old-file` in the
 556index).  'GIT_EXTERNAL_DIFF' should not worry about unlinking the
 557temporary file --- it is removed when 'GIT_EXTERNAL_DIFF' exits.
 558+
 559For a path that is unmerged, 'GIT_EXTERNAL_DIFF' is called with 1
 560parameter, <path>.
 561
 562other
 563~~~~~
 564'GIT_MERGE_VERBOSITY'::
 565        A number controlling the amount of output shown by
 566        the recursive merge strategy.  Overrides merge.verbosity.
 567        See linkgit:git-merge[1]
 568
 569'GIT_PAGER'::
 570        This environment variable overrides `$PAGER`. If it is set
 571        to an empty string or to the value "cat", git will not launch
 572        a pager.  See also the `core.pager` option in
 573        linkgit:git-config[1].
 574
 575'GIT_SSH'::
 576        If this environment variable is set then 'git-fetch'
 577        and 'git-push' will use this command instead
 578        of 'ssh' when they need to connect to a remote system.
 579        The '$GIT_SSH' command will be given exactly two arguments:
 580        the 'username@host' (or just 'host') from the URL and the
 581        shell command to execute on that remote system.
 582+
 583To pass options to the program that you want to list in GIT_SSH
 584you will need to wrap the program and options into a shell script,
 585then set GIT_SSH to refer to the shell script.
 586+
 587Usually it is easier to configure any desired options through your
 588personal `.ssh/config` file.  Please consult your ssh documentation
 589for further details.
 590
 591'GIT_FLUSH'::
 592        If this environment variable is set to "1", then commands such
 593        as 'git-blame' (in incremental mode), 'git-rev-list', 'git-log',
 594        and 'git-whatchanged' will force a flush of the output stream
 595        after each commit-oriented record have been flushed.   If this
 596        variable is set to "0", the output of these commands will be done
 597        using completely buffered I/O.   If this environment variable is
 598        not set, git will choose buffered or record-oriented flushing
 599        based on whether stdout appears to be redirected to a file or not.
 600
 601'GIT_TRACE'::
 602        If this variable is set to "1", "2" or "true" (comparison
 603        is case insensitive), git will print `trace:` messages on
 604        stderr telling about alias expansion, built-in command
 605        execution and external command execution.
 606        If this variable is set to an integer value greater than 1
 607        and lower than 10 (strictly) then git will interpret this
 608        value as an open file descriptor and will try to write the
 609        trace messages into this file descriptor.
 610        Alternatively, if this variable is set to an absolute path
 611        (starting with a '/' character), git will interpret this
 612        as a file path and will try to write the trace messages
 613        into it.
 614
 615Discussion[[Discussion]]
 616------------------------
 617
 618More detail on the following is available from the
 619link:user-manual.html#git-concepts[git concepts chapter of the
 620user-manual] and linkgit:gitcore-tutorial[7].
 621
 622A git project normally consists of a working directory with a ".git"
 623subdirectory at the top level.  The .git directory contains, among other
 624things, a compressed object database representing the complete history
 625of the project, an "index" file which links that history to the current
 626contents of the working tree, and named pointers into that history such
 627as tags and branch heads.
 628
 629The object database contains objects of three main types: blobs, which
 630hold file data; trees, which point to blobs and other trees to build up
 631directory hierarchies; and commits, which each reference a single tree
 632and some number of parent commits.
 633
 634The commit, equivalent to what other systems call a "changeset" or
 635"version", represents a step in the project's history, and each parent
 636represents an immediately preceding step.  Commits with more than one
 637parent represent merges of independent lines of development.
 638
 639All objects are named by the SHA1 hash of their contents, normally
 640written as a string of 40 hex digits.  Such names are globally unique.
 641The entire history leading up to a commit can be vouched for by signing
 642just that commit.  A fourth object type, the tag, is provided for this
 643purpose.
 644
 645When first created, objects are stored in individual files, but for
 646efficiency may later be compressed together into "pack files".
 647
 648Named pointers called refs mark interesting points in history.  A ref
 649may contain the SHA1 name of an object or the name of another ref.  Refs
 650with names beginning `ref/head/` contain the SHA1 name of the most
 651recent commit (or "head") of a branch under development.  SHA1 names of
 652tags of interest are stored under `ref/tags/`.  A special ref named
 653`HEAD` contains the name of the currently checked-out branch.
 654
 655The index file is initialized with a list of all paths and, for each
 656path, a blob object and a set of attributes.  The blob object represents
 657the contents of the file as of the head of the current branch.  The
 658attributes (last modified time, size, etc.) are taken from the
 659corresponding file in the working tree.  Subsequent changes to the
 660working tree can be found by comparing these attributes.  The index may
 661be updated with new content, and new commits may be created from the
 662content stored in the index.
 663
 664The index is also capable of storing multiple entries (called "stages")
 665for a given pathname.  These stages are used to hold the various
 666unmerged version of a file when a merge is in progress.
 667
 668Authors
 669-------
 670* git's founding father is Linus Torvalds <torvalds@osdl.org>.
 671* The current git nurse is Junio C Hamano <gitster@pobox.com>.
 672* The git potty was written by Andreas Ericsson <ae@op5.se>.
 673* General upbringing is handled by the git-list <git@vger.kernel.org>.
 674
 675Documentation
 676--------------
 677The documentation for git suite was started by David Greaves
 678<david@dgreaves.com>, and later enhanced greatly by the
 679contributors on the git-list <git@vger.kernel.org>.
 680
 681SEE ALSO
 682--------
 683linkgit:gittutorial[7], linkgit:gittutorial-2[7],
 684link:everyday.html[Everyday Git], linkgit:gitcvs-migration[7],
 685linkgit:gitglossary[7], linkgit:gitcore-tutorial[7],
 686linkgit:gitcli[7], link:user-manual.html[The Git User's Manual],
 687linkgit:gitworkflows[7]
 688
 689GIT
 690---
 691Part of the linkgit:git[1] suite