Documentation / git.txton commit Merge branch 'maint' to sync with 1.6.5.7 (a1bb8f4)
   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:v1.6.5.7/git.html[documentation for release 1.6.5.7]
  47
  48* release notes for
  49  link:RelNotes-1.6.5.7.txt[1.6.5.7],
  50  link:RelNotes-1.6.5.6.txt[1.6.5.6],
  51  link:RelNotes-1.6.5.5.txt[1.6.5.5],
  52  link:RelNotes-1.6.5.4.txt[1.6.5.4],
  53  link:RelNotes-1.6.5.3.txt[1.6.5.3],
  54  link:RelNotes-1.6.5.2.txt[1.6.5.2],
  55  link:RelNotes-1.6.5.1.txt[1.6.5.1],
  56  link:RelNotes-1.6.5.txt[1.6.5].
  57
  58* link:v1.6.4.4/git.html[documentation for release 1.6.4.4]
  59
  60* release notes for
  61  link:RelNotes-1.6.4.4.txt[1.6.4.4],
  62  link:RelNotes-1.6.4.3.txt[1.6.4.3],
  63  link:RelNotes-1.6.4.2.txt[1.6.4.2],
  64  link:RelNotes-1.6.4.1.txt[1.6.4.1],
  65  link:RelNotes-1.6.4.txt[1.6.4].
  66
  67* link:v1.6.3.4/git.html[documentation for release 1.6.3.4]
  68
  69* release notes for
  70  link:RelNotes-1.6.3.4.txt[1.6.3.4],
  71  link:RelNotes-1.6.3.3.txt[1.6.3.3],
  72  link:RelNotes-1.6.3.2.txt[1.6.3.2],
  73  link:RelNotes-1.6.3.1.txt[1.6.3.1],
  74  link:RelNotes-1.6.3.txt[1.6.3].
  75
  76* release notes for
  77  link:RelNotes-1.6.2.5.txt[1.6.2.5],
  78  link:RelNotes-1.6.2.4.txt[1.6.2.4],
  79  link:RelNotes-1.6.2.3.txt[1.6.2.3],
  80  link:RelNotes-1.6.2.2.txt[1.6.2.2],
  81  link:RelNotes-1.6.2.1.txt[1.6.2.1],
  82  link:RelNotes-1.6.2.txt[1.6.2].
  83
  84* link:v1.6.1.3/git.html[documentation for release 1.6.1.3]
  85
  86* release notes for
  87  link:RelNotes-1.6.1.3.txt[1.6.1.3],
  88  link:RelNotes-1.6.1.2.txt[1.6.1.2],
  89  link:RelNotes-1.6.1.1.txt[1.6.1.1],
  90  link:RelNotes-1.6.1.txt[1.6.1].
  91
  92* link:v1.6.0.6/git.html[documentation for release 1.6.0.6]
  93
  94* release notes for
  95  link:RelNotes-1.6.0.6.txt[1.6.0.6],
  96  link:RelNotes-1.6.0.5.txt[1.6.0.5],
  97  link:RelNotes-1.6.0.4.txt[1.6.0.4],
  98  link:RelNotes-1.6.0.3.txt[1.6.0.3],
  99  link:RelNotes-1.6.0.2.txt[1.6.0.2],
 100  link:RelNotes-1.6.0.1.txt[1.6.0.1],
 101  link:RelNotes-1.6.0.txt[1.6.0].
 102
 103* link:v1.5.6.6/git.html[documentation for release 1.5.6.6]
 104
 105* release notes for
 106  link:RelNotes-1.5.6.6.txt[1.5.6.6],
 107  link:RelNotes-1.5.6.5.txt[1.5.6.5],
 108  link:RelNotes-1.5.6.4.txt[1.5.6.4],
 109  link:RelNotes-1.5.6.3.txt[1.5.6.3],
 110  link:RelNotes-1.5.6.2.txt[1.5.6.2],
 111  link:RelNotes-1.5.6.1.txt[1.5.6.1],
 112  link:RelNotes-1.5.6.txt[1.5.6].
 113
 114* link:v1.5.5.6/git.html[documentation for release 1.5.5.6]
 115
 116* release notes for
 117  link:RelNotes-1.5.5.6.txt[1.5.5.6],
 118  link:RelNotes-1.5.5.5.txt[1.5.5.5],
 119  link:RelNotes-1.5.5.4.txt[1.5.5.4],
 120  link:RelNotes-1.5.5.3.txt[1.5.5.3],
 121  link:RelNotes-1.5.5.2.txt[1.5.5.2],
 122  link:RelNotes-1.5.5.1.txt[1.5.5.1],
 123  link:RelNotes-1.5.5.txt[1.5.5].
 124
 125* link:v1.5.4.7/git.html[documentation for release 1.5.4.7]
 126
 127* release notes for
 128  link:RelNotes-1.5.4.7.txt[1.5.4.7],
 129  link:RelNotes-1.5.4.6.txt[1.5.4.6],
 130  link:RelNotes-1.5.4.5.txt[1.5.4.5],
 131  link:RelNotes-1.5.4.4.txt[1.5.4.4],
 132  link:RelNotes-1.5.4.3.txt[1.5.4.3],
 133  link:RelNotes-1.5.4.2.txt[1.5.4.2],
 134  link:RelNotes-1.5.4.1.txt[1.5.4.1],
 135  link:RelNotes-1.5.4.txt[1.5.4].
 136
 137* link:v1.5.3.8/git.html[documentation for release 1.5.3.8]
 138
 139* release notes for
 140  link:RelNotes-1.5.3.8.txt[1.5.3.8],
 141  link:RelNotes-1.5.3.7.txt[1.5.3.7],
 142  link:RelNotes-1.5.3.6.txt[1.5.3.6],
 143  link:RelNotes-1.5.3.5.txt[1.5.3.5],
 144  link:RelNotes-1.5.3.4.txt[1.5.3.4],
 145  link:RelNotes-1.5.3.3.txt[1.5.3.3],
 146  link:RelNotes-1.5.3.2.txt[1.5.3.2],
 147  link:RelNotes-1.5.3.1.txt[1.5.3.1],
 148  link:RelNotes-1.5.3.txt[1.5.3].
 149
 150* link:v1.5.2.5/git.html[documentation for release 1.5.2.5]
 151
 152* release notes for
 153  link:RelNotes-1.5.2.5.txt[1.5.2.5],
 154  link:RelNotes-1.5.2.4.txt[1.5.2.4],
 155  link:RelNotes-1.5.2.3.txt[1.5.2.3],
 156  link:RelNotes-1.5.2.2.txt[1.5.2.2],
 157  link:RelNotes-1.5.2.1.txt[1.5.2.1],
 158  link:RelNotes-1.5.2.txt[1.5.2].
 159
 160* link:v1.5.1.6/git.html[documentation for release 1.5.1.6]
 161
 162* release notes for
 163  link:RelNotes-1.5.1.6.txt[1.5.1.6],
 164  link:RelNotes-1.5.1.5.txt[1.5.1.5],
 165  link:RelNotes-1.5.1.4.txt[1.5.1.4],
 166  link:RelNotes-1.5.1.3.txt[1.5.1.3],
 167  link:RelNotes-1.5.1.2.txt[1.5.1.2],
 168  link:RelNotes-1.5.1.1.txt[1.5.1.1],
 169  link:RelNotes-1.5.1.txt[1.5.1].
 170
 171* link:v1.5.0.7/git.html[documentation for release 1.5.0.7]
 172
 173* release notes for
 174  link:RelNotes-1.5.0.7.txt[1.5.0.7],
 175  link:RelNotes-1.5.0.6.txt[1.5.0.6],
 176  link:RelNotes-1.5.0.5.txt[1.5.0.5],
 177  link:RelNotes-1.5.0.3.txt[1.5.0.3],
 178  link:RelNotes-1.5.0.2.txt[1.5.0.2],
 179  link:RelNotes-1.5.0.1.txt[1.5.0.1],
 180  link:RelNotes-1.5.0.txt[1.5.0].
 181
 182* documentation for release link:v1.4.4.4/git.html[1.4.4.4],
 183  link:v1.3.3/git.html[1.3.3],
 184  link:v1.2.6/git.html[1.2.6],
 185  link:v1.0.13/git.html[1.0.13].
 186
 187============
 188
 189endif::stalenotes[]
 190
 191OPTIONS
 192-------
 193--version::
 194        Prints the git suite version that the 'git' program came from.
 195
 196--help::
 197        Prints the synopsis and a list of the most commonly used
 198        commands. If the option '--all' or '-a' is given then all
 199        available commands are printed. If a git command is named this
 200        option will bring up the manual page for that command.
 201+
 202Other options are available to control how the manual page is
 203displayed. See linkgit:git-help[1] for more information,
 204because `git --help ...` is converted internally into `git
 205help ...`.
 206
 207--exec-path::
 208        Path to wherever your core git programs are installed.
 209        This can also be controlled by setting the GIT_EXEC_PATH
 210        environment variable. If no path is given, 'git' will print
 211        the current setting and then exit.
 212
 213--html-path::
 214        Print the path to wherever your git HTML documentation is installed
 215        and exit.
 216
 217-p::
 218--paginate::
 219        Pipe all output into 'less' (or if set, $PAGER).
 220
 221--no-pager::
 222        Do not pipe git output into a pager.
 223
 224--git-dir=<path>::
 225        Set the path to the repository. This can also be controlled by
 226        setting the GIT_DIR environment variable. It can be an absolute
 227        path or relative path to current working directory.
 228
 229--work-tree=<path>::
 230        Set the path to the working tree.  The value will not be
 231        used in combination with repositories found automatically in
 232        a .git directory (i.e. $GIT_DIR is not set).
 233        This can also be controlled by setting the GIT_WORK_TREE
 234        environment variable and the core.worktree configuration
 235        variable. It can be an absolute path or relative path to
 236        the directory specified by --git-dir or GIT_DIR.
 237        Note: If --git-dir or GIT_DIR are specified but none of
 238        --work-tree, GIT_WORK_TREE and core.worktree is specified,
 239        the current working directory is regarded as the top directory
 240        of your working tree.
 241
 242--bare::
 243        Treat the repository as a bare repository.  If GIT_DIR
 244        environment is not set, it is set to the current working
 245        directory.
 246
 247--no-replace-objects::
 248        Do not use replacement refs to replace git objects. See
 249        linkgit:git-replace[1] for more information.
 250
 251
 252FURTHER DOCUMENTATION
 253---------------------
 254
 255See the references above to get started using git.  The following is
 256probably more detail than necessary for a first-time user.
 257
 258The link:user-manual.html#git-concepts[git concepts chapter of the
 259user-manual] and linkgit:gitcore-tutorial[7] both provide
 260introductions to the underlying git architecture.
 261
 262See linkgit:gitworkflows[7] for an overview of recommended workflows.
 263
 264See also the link:howto-index.html[howto] documents for some useful
 265examples.
 266
 267The internals are documented in the
 268link:technical/api-index.html[GIT API documentation].
 269
 270GIT COMMANDS
 271------------
 272
 273We divide git into high level ("porcelain") commands and low level
 274("plumbing") commands.
 275
 276High-level commands (porcelain)
 277-------------------------------
 278
 279We separate the porcelain commands into the main commands and some
 280ancillary user utilities.
 281
 282Main porcelain commands
 283~~~~~~~~~~~~~~~~~~~~~~~
 284
 285include::cmds-mainporcelain.txt[]
 286
 287Ancillary Commands
 288~~~~~~~~~~~~~~~~~~
 289Manipulators:
 290
 291include::cmds-ancillarymanipulators.txt[]
 292
 293Interrogators:
 294
 295include::cmds-ancillaryinterrogators.txt[]
 296
 297
 298Interacting with Others
 299~~~~~~~~~~~~~~~~~~~~~~~
 300
 301These commands are to interact with foreign SCM and with other
 302people via patch over e-mail.
 303
 304include::cmds-foreignscminterface.txt[]
 305
 306
 307Low-level commands (plumbing)
 308-----------------------------
 309
 310Although git includes its
 311own porcelain layer, its low-level commands are sufficient to support
 312development of alternative porcelains.  Developers of such porcelains
 313might start by reading about linkgit:git-update-index[1] and
 314linkgit:git-read-tree[1].
 315
 316The interface (input, output, set of options and the semantics)
 317to these low-level commands are meant to be a lot more stable
 318than Porcelain level commands, because these commands are
 319primarily for scripted use.  The interface to Porcelain commands
 320on the other hand are subject to change in order to improve the
 321end user experience.
 322
 323The following description divides
 324the low-level commands into commands that manipulate objects (in
 325the repository, index, and working tree), commands that interrogate and
 326compare objects, and commands that move objects and references between
 327repositories.
 328
 329
 330Manipulation commands
 331~~~~~~~~~~~~~~~~~~~~~
 332
 333include::cmds-plumbingmanipulators.txt[]
 334
 335
 336Interrogation commands
 337~~~~~~~~~~~~~~~~~~~~~~
 338
 339include::cmds-plumbinginterrogators.txt[]
 340
 341In general, the interrogate commands do not touch the files in
 342the working tree.
 343
 344
 345Synching repositories
 346~~~~~~~~~~~~~~~~~~~~~
 347
 348include::cmds-synchingrepositories.txt[]
 349
 350The following are helper commands used by the above; end users
 351typically do not use them directly.
 352
 353include::cmds-synchelpers.txt[]
 354
 355
 356Internal helper commands
 357~~~~~~~~~~~~~~~~~~~~~~~~
 358
 359These are internal helper commands used by other commands; end
 360users typically do not use them directly.
 361
 362include::cmds-purehelpers.txt[]
 363
 364
 365Configuration Mechanism
 366-----------------------
 367
 368Starting from 0.99.9 (actually mid 0.99.8.GIT), `.git/config` file
 369is used to hold per-repository configuration options.  It is a
 370simple text file modeled after `.ini` format familiar to some
 371people.  Here is an example:
 372
 373------------
 374#
 375# A '#' or ';' character indicates a comment.
 376#
 377
 378; core variables
 379[core]
 380        ; Don't trust file modes
 381        filemode = false
 382
 383; user identity
 384[user]
 385        name = "Junio C Hamano"
 386        email = "junkio@twinsun.com"
 387
 388------------
 389
 390Various commands read from the configuration file and adjust
 391their operation accordingly.
 392
 393
 394Identifier Terminology
 395----------------------
 396<object>::
 397        Indicates the object name for any type of object.
 398
 399<blob>::
 400        Indicates a blob object name.
 401
 402<tree>::
 403        Indicates a tree object name.
 404
 405<commit>::
 406        Indicates a commit object name.
 407
 408<tree-ish>::
 409        Indicates a tree, commit or tag object name.  A
 410        command that takes a <tree-ish> argument ultimately wants to
 411        operate on a <tree> object but automatically dereferences
 412        <commit> and <tag> objects that point at a <tree>.
 413
 414<commit-ish>::
 415        Indicates a commit or tag object name.  A
 416        command that takes a <commit-ish> argument ultimately wants to
 417        operate on a <commit> object but automatically dereferences
 418        <tag> objects that point at a <commit>.
 419
 420<type>::
 421        Indicates that an object type is required.
 422        Currently one of: `blob`, `tree`, `commit`, or `tag`.
 423
 424<file>::
 425        Indicates a filename - almost always relative to the
 426        root of the tree structure `GIT_INDEX_FILE` describes.
 427
 428Symbolic Identifiers
 429--------------------
 430Any git command accepting any <object> can also use the following
 431symbolic notation:
 432
 433HEAD::
 434        indicates the head of the current branch (i.e. the
 435        contents of `$GIT_DIR/HEAD`).
 436
 437<tag>::
 438        a valid tag 'name'
 439        (i.e. the contents of `$GIT_DIR/refs/tags/<tag>`).
 440
 441<head>::
 442        a valid head 'name'
 443        (i.e. the contents of `$GIT_DIR/refs/heads/<head>`).
 444
 445For a more complete list of ways to spell object names, see
 446"SPECIFYING REVISIONS" section in linkgit:git-rev-parse[1].
 447
 448
 449File/Directory Structure
 450------------------------
 451
 452Please see the linkgit:gitrepository-layout[5] document.
 453
 454Read linkgit:githooks[5] for more details about each hook.
 455
 456Higher level SCMs may provide and manage additional information in the
 457`$GIT_DIR`.
 458
 459
 460Terminology
 461-----------
 462Please see linkgit:gitglossary[7].
 463
 464
 465Environment Variables
 466---------------------
 467Various git commands use the following environment variables:
 468
 469The git Repository
 470~~~~~~~~~~~~~~~~~~
 471These environment variables apply to 'all' core git commands. Nb: it
 472is worth noting that they may be used/overridden by SCMS sitting above
 473git so take care if using Cogito etc.
 474
 475'GIT_INDEX_FILE'::
 476        This environment allows the specification of an alternate
 477        index file. If not specified, the default of `$GIT_DIR/index`
 478        is used.
 479
 480'GIT_OBJECT_DIRECTORY'::
 481        If the object storage directory is specified via this
 482        environment variable then the sha1 directories are created
 483        underneath - otherwise the default `$GIT_DIR/objects`
 484        directory is used.
 485
 486'GIT_ALTERNATE_OBJECT_DIRECTORIES'::
 487        Due to the immutable nature of git objects, old objects can be
 488        archived into shared, read-only directories. This variable
 489        specifies a ":" separated (on Windows ";" separated) list
 490        of git object directories which can be used to search for git
 491        objects. New objects will not be written to these directories.
 492
 493'GIT_DIR'::
 494        If the 'GIT_DIR' environment variable is set then it
 495        specifies a path to use instead of the default `.git`
 496        for the base of the repository.
 497
 498'GIT_WORK_TREE'::
 499        Set the path to the working tree.  The value will not be
 500        used in combination with repositories found automatically in
 501        a .git directory (i.e. $GIT_DIR is not set).
 502        This can also be controlled by the '--work-tree' command line
 503        option and the core.worktree configuration variable.
 504
 505'GIT_CEILING_DIRECTORIES'::
 506        This should be a colon-separated list of absolute paths.
 507        If set, it is a list of directories that git should not chdir
 508        up into while looking for a repository directory.
 509        It will not exclude the current working directory or
 510        a GIT_DIR set on the command line or in the environment.
 511        (Useful for excluding slow-loading network directories.)
 512
 513git Commits
 514~~~~~~~~~~~
 515'GIT_AUTHOR_NAME'::
 516'GIT_AUTHOR_EMAIL'::
 517'GIT_AUTHOR_DATE'::
 518'GIT_COMMITTER_NAME'::
 519'GIT_COMMITTER_EMAIL'::
 520'GIT_COMMITTER_DATE'::
 521'EMAIL'::
 522        see linkgit:git-commit-tree[1]
 523
 524git Diffs
 525~~~~~~~~~
 526'GIT_DIFF_OPTS'::
 527        Only valid setting is "--unified=??" or "-u??" to set the
 528        number of context lines shown when a unified diff is created.
 529        This takes precedence over any "-U" or "--unified" option
 530        value passed on the git diff command line.
 531
 532'GIT_EXTERNAL_DIFF'::
 533        When the environment variable 'GIT_EXTERNAL_DIFF' is set, the
 534        program named by it is called, instead of the diff invocation
 535        described above.  For a path that is added, removed, or modified,
 536        'GIT_EXTERNAL_DIFF' is called with 7 parameters:
 537
 538        path old-file old-hex old-mode new-file new-hex new-mode
 539+
 540where:
 541
 542        <old|new>-file:: are files GIT_EXTERNAL_DIFF can use to read the
 543                         contents of <old|new>,
 544        <old|new>-hex:: are the 40-hexdigit SHA1 hashes,
 545        <old|new>-mode:: are the octal representation of the file modes.
 546
 547+
 548The file parameters can point at the user's working file
 549(e.g. `new-file` in "git-diff-files"), `/dev/null` (e.g. `old-file`
 550when a new file is added), or a temporary file (e.g. `old-file` in the
 551index).  'GIT_EXTERNAL_DIFF' should not worry about unlinking the
 552temporary file --- it is removed when 'GIT_EXTERNAL_DIFF' exits.
 553+
 554For a path that is unmerged, 'GIT_EXTERNAL_DIFF' is called with 1
 555parameter, <path>.
 556
 557other
 558~~~~~
 559'GIT_MERGE_VERBOSITY'::
 560        A number controlling the amount of output shown by
 561        the recursive merge strategy.  Overrides merge.verbosity.
 562        See linkgit:git-merge[1]
 563
 564'GIT_PAGER'::
 565        This environment variable overrides `$PAGER`. If it is set
 566        to an empty string or to the value "cat", git will not launch
 567        a pager.  See also the `core.pager` option in
 568        linkgit:git-config[1].
 569
 570'GIT_SSH'::
 571        If this environment variable is set then 'git-fetch'
 572        and 'git-push' will use this command instead
 573        of 'ssh' when they need to connect to a remote system.
 574        The '$GIT_SSH' command will be given exactly two arguments:
 575        the 'username@host' (or just 'host') from the URL and the
 576        shell command to execute on that remote system.
 577+
 578To pass options to the program that you want to list in GIT_SSH
 579you will need to wrap the program and options into a shell script,
 580then set GIT_SSH to refer to the shell script.
 581+
 582Usually it is easier to configure any desired options through your
 583personal `.ssh/config` file.  Please consult your ssh documentation
 584for further details.
 585
 586'GIT_FLUSH'::
 587        If this environment variable is set to "1", then commands such
 588        as 'git-blame' (in incremental mode), 'git-rev-list', 'git-log',
 589        and 'git-whatchanged' will force a flush of the output stream
 590        after each commit-oriented record have been flushed.   If this
 591        variable is set to "0", the output of these commands will be done
 592        using completely buffered I/O.   If this environment variable is
 593        not set, git will choose buffered or record-oriented flushing
 594        based on whether stdout appears to be redirected to a file or not.
 595
 596'GIT_TRACE'::
 597        If this variable is set to "1", "2" or "true" (comparison
 598        is case insensitive), git will print `trace:` messages on
 599        stderr telling about alias expansion, built-in command
 600        execution and external command execution.
 601        If this variable is set to an integer value greater than 1
 602        and lower than 10 (strictly) then git will interpret this
 603        value as an open file descriptor and will try to write the
 604        trace messages into this file descriptor.
 605        Alternatively, if this variable is set to an absolute path
 606        (starting with a '/' character), git will interpret this
 607        as a file path and will try to write the trace messages
 608        into it.
 609
 610Discussion[[Discussion]]
 611------------------------
 612
 613More detail on the following is available from the
 614link:user-manual.html#git-concepts[git concepts chapter of the
 615user-manual] and linkgit:gitcore-tutorial[7].
 616
 617A git project normally consists of a working directory with a ".git"
 618subdirectory at the top level.  The .git directory contains, among other
 619things, a compressed object database representing the complete history
 620of the project, an "index" file which links that history to the current
 621contents of the working tree, and named pointers into that history such
 622as tags and branch heads.
 623
 624The object database contains objects of three main types: blobs, which
 625hold file data; trees, which point to blobs and other trees to build up
 626directory hierarchies; and commits, which each reference a single tree
 627and some number of parent commits.
 628
 629The commit, equivalent to what other systems call a "changeset" or
 630"version", represents a step in the project's history, and each parent
 631represents an immediately preceding step.  Commits with more than one
 632parent represent merges of independent lines of development.
 633
 634All objects are named by the SHA1 hash of their contents, normally
 635written as a string of 40 hex digits.  Such names are globally unique.
 636The entire history leading up to a commit can be vouched for by signing
 637just that commit.  A fourth object type, the tag, is provided for this
 638purpose.
 639
 640When first created, objects are stored in individual files, but for
 641efficiency may later be compressed together into "pack files".
 642
 643Named pointers called refs mark interesting points in history.  A ref
 644may contain the SHA1 name of an object or the name of another ref.  Refs
 645with names beginning `ref/head/` contain the SHA1 name of the most
 646recent commit (or "head") of a branch under development.  SHA1 names of
 647tags of interest are stored under `ref/tags/`.  A special ref named
 648`HEAD` contains the name of the currently checked-out branch.
 649
 650The index file is initialized with a list of all paths and, for each
 651path, a blob object and a set of attributes.  The blob object represents
 652the contents of the file as of the head of the current branch.  The
 653attributes (last modified time, size, etc.) are taken from the
 654corresponding file in the working tree.  Subsequent changes to the
 655working tree can be found by comparing these attributes.  The index may
 656be updated with new content, and new commits may be created from the
 657content stored in the index.
 658
 659The index is also capable of storing multiple entries (called "stages")
 660for a given pathname.  These stages are used to hold the various
 661unmerged version of a file when a merge is in progress.
 662
 663Authors
 664-------
 665* git's founding father is Linus Torvalds <torvalds@osdl.org>.
 666* The current git nurse is Junio C Hamano <gitster@pobox.com>.
 667* The git potty was written by Andreas Ericsson <ae@op5.se>.
 668* General upbringing is handled by the git-list <git@vger.kernel.org>.
 669
 670Documentation
 671--------------
 672The documentation for git suite was started by David Greaves
 673<david@dgreaves.com>, and later enhanced greatly by the
 674contributors on the git-list <git@vger.kernel.org>.
 675
 676SEE ALSO
 677--------
 678linkgit:gittutorial[7], linkgit:gittutorial-2[7],
 679link:everyday.html[Everyday Git], linkgit:gitcvs-migration[7],
 680linkgit:gitglossary[7], linkgit:gitcore-tutorial[7],
 681linkgit:gitcli[7], link:user-manual.html[The Git User's Manual],
 682linkgit:gitworkflows[7]
 683
 684GIT
 685---
 686Part of the linkgit:git[1] suite