Documentation / git.txton commit Merge branch 'rs/work-around-grep-opt-insanity' into maint (957f5db)
   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]
  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:v1.6.5.4/git.html[documentation for release 1.6.5.4]
  47
  48* release notes for
  49  link:RelNotes-1.6.5.4.txt[1.6.5.4],
  50  link:RelNotes-1.6.5.3.txt[1.6.5.3],
  51  link:RelNotes-1.6.5.2.txt[1.6.5.2],
  52  link:RelNotes-1.6.5.1.txt[1.6.5.1],
  53  link:RelNotes-1.6.5.txt[1.6.5].
  54
  55* link:v1.6.4.4/git.html[documentation for release 1.6.4.4]
  56
  57* release notes for
  58  link:RelNotes-1.6.4.4.txt[1.6.4.4],
  59  link:RelNotes-1.6.4.3.txt[1.6.4.3],
  60  link:RelNotes-1.6.4.2.txt[1.6.4.2],
  61  link:RelNotes-1.6.4.1.txt[1.6.4.1],
  62  link:RelNotes-1.6.4.txt[1.6.4].
  63
  64* link:v1.6.3.4/git.html[documentation for release 1.6.3.4]
  65
  66* release notes for
  67  link:RelNotes-1.6.3.4.txt[1.6.3.4],
  68  link:RelNotes-1.6.3.3.txt[1.6.3.3],
  69  link:RelNotes-1.6.3.2.txt[1.6.3.2],
  70  link:RelNotes-1.6.3.1.txt[1.6.3.1],
  71  link:RelNotes-1.6.3.txt[1.6.3].
  72
  73* release notes for
  74  link:RelNotes-1.6.2.5.txt[1.6.2.5],
  75  link:RelNotes-1.6.2.4.txt[1.6.2.4],
  76  link:RelNotes-1.6.2.3.txt[1.6.2.3],
  77  link:RelNotes-1.6.2.2.txt[1.6.2.2],
  78  link:RelNotes-1.6.2.1.txt[1.6.2.1],
  79  link:RelNotes-1.6.2.txt[1.6.2].
  80
  81* link:v1.6.1.3/git.html[documentation for release 1.6.1.3]
  82
  83* release notes for
  84  link:RelNotes-1.6.1.3.txt[1.6.1.3],
  85  link:RelNotes-1.6.1.2.txt[1.6.1.2],
  86  link:RelNotes-1.6.1.1.txt[1.6.1.1],
  87  link:RelNotes-1.6.1.txt[1.6.1].
  88
  89* link:v1.6.0.6/git.html[documentation for release 1.6.0.6]
  90
  91* release notes for
  92  link:RelNotes-1.6.0.6.txt[1.6.0.6],
  93  link:RelNotes-1.6.0.5.txt[1.6.0.5],
  94  link:RelNotes-1.6.0.4.txt[1.6.0.4],
  95  link:RelNotes-1.6.0.3.txt[1.6.0.3],
  96  link:RelNotes-1.6.0.2.txt[1.6.0.2],
  97  link:RelNotes-1.6.0.1.txt[1.6.0.1],
  98  link:RelNotes-1.6.0.txt[1.6.0].
  99
 100* link:v1.5.6.6/git.html[documentation for release 1.5.6.6]
 101
 102* release notes for
 103  link:RelNotes-1.5.6.6.txt[1.5.6.6],
 104  link:RelNotes-1.5.6.5.txt[1.5.6.5],
 105  link:RelNotes-1.5.6.4.txt[1.5.6.4],
 106  link:RelNotes-1.5.6.3.txt[1.5.6.3],
 107  link:RelNotes-1.5.6.2.txt[1.5.6.2],
 108  link:RelNotes-1.5.6.1.txt[1.5.6.1],
 109  link:RelNotes-1.5.6.txt[1.5.6].
 110
 111* link:v1.5.5.6/git.html[documentation for release 1.5.5.6]
 112
 113* release notes for
 114  link:RelNotes-1.5.5.6.txt[1.5.5.6],
 115  link:RelNotes-1.5.5.5.txt[1.5.5.5],
 116  link:RelNotes-1.5.5.4.txt[1.5.5.4],
 117  link:RelNotes-1.5.5.3.txt[1.5.5.3],
 118  link:RelNotes-1.5.5.2.txt[1.5.5.2],
 119  link:RelNotes-1.5.5.1.txt[1.5.5.1],
 120  link:RelNotes-1.5.5.txt[1.5.5].
 121
 122* link:v1.5.4.7/git.html[documentation for release 1.5.4.7]
 123
 124* release notes for
 125  link:RelNotes-1.5.4.7.txt[1.5.4.7],
 126  link:RelNotes-1.5.4.6.txt[1.5.4.6],
 127  link:RelNotes-1.5.4.5.txt[1.5.4.5],
 128  link:RelNotes-1.5.4.4.txt[1.5.4.4],
 129  link:RelNotes-1.5.4.3.txt[1.5.4.3],
 130  link:RelNotes-1.5.4.2.txt[1.5.4.2],
 131  link:RelNotes-1.5.4.1.txt[1.5.4.1],
 132  link:RelNotes-1.5.4.txt[1.5.4].
 133
 134* link:v1.5.3.8/git.html[documentation for release 1.5.3.8]
 135
 136* release notes for
 137  link:RelNotes-1.5.3.8.txt[1.5.3.8],
 138  link:RelNotes-1.5.3.7.txt[1.5.3.7],
 139  link:RelNotes-1.5.3.6.txt[1.5.3.6],
 140  link:RelNotes-1.5.3.5.txt[1.5.3.5],
 141  link:RelNotes-1.5.3.4.txt[1.5.3.4],
 142  link:RelNotes-1.5.3.3.txt[1.5.3.3],
 143  link:RelNotes-1.5.3.2.txt[1.5.3.2],
 144  link:RelNotes-1.5.3.1.txt[1.5.3.1],
 145  link:RelNotes-1.5.3.txt[1.5.3].
 146
 147* link:v1.5.2.5/git.html[documentation for release 1.5.2.5]
 148
 149* release notes for
 150  link:RelNotes-1.5.2.5.txt[1.5.2.5],
 151  link:RelNotes-1.5.2.4.txt[1.5.2.4],
 152  link:RelNotes-1.5.2.3.txt[1.5.2.3],
 153  link:RelNotes-1.5.2.2.txt[1.5.2.2],
 154  link:RelNotes-1.5.2.1.txt[1.5.2.1],
 155  link:RelNotes-1.5.2.txt[1.5.2].
 156
 157* link:v1.5.1.6/git.html[documentation for release 1.5.1.6]
 158
 159* release notes for
 160  link:RelNotes-1.5.1.6.txt[1.5.1.6],
 161  link:RelNotes-1.5.1.5.txt[1.5.1.5],
 162  link:RelNotes-1.5.1.4.txt[1.5.1.4],
 163  link:RelNotes-1.5.1.3.txt[1.5.1.3],
 164  link:RelNotes-1.5.1.2.txt[1.5.1.2],
 165  link:RelNotes-1.5.1.1.txt[1.5.1.1],
 166  link:RelNotes-1.5.1.txt[1.5.1].
 167
 168* link:v1.5.0.7/git.html[documentation for release 1.5.0.7]
 169
 170* release notes for
 171  link:RelNotes-1.5.0.7.txt[1.5.0.7],
 172  link:RelNotes-1.5.0.6.txt[1.5.0.6],
 173  link:RelNotes-1.5.0.5.txt[1.5.0.5],
 174  link:RelNotes-1.5.0.3.txt[1.5.0.3],
 175  link:RelNotes-1.5.0.2.txt[1.5.0.2],
 176  link:RelNotes-1.5.0.1.txt[1.5.0.1],
 177  link:RelNotes-1.5.0.txt[1.5.0].
 178
 179* documentation for release link:v1.4.4.4/git.html[1.4.4.4],
 180  link:v1.3.3/git.html[1.3.3],
 181  link:v1.2.6/git.html[1.2.6],
 182  link:v1.0.13/git.html[1.0.13].
 183
 184============
 185
 186endif::stalenotes[]
 187
 188OPTIONS
 189-------
 190--version::
 191        Prints the git suite version that the 'git' program came from.
 192
 193--help::
 194        Prints the synopsis and a list of the most commonly used
 195        commands. If the option '--all' or '-a' is given then all
 196        available commands are printed. If a git command is named this
 197        option will bring up the manual page for that command.
 198+
 199Other options are available to control how the manual page is
 200displayed. See linkgit:git-help[1] for more information,
 201because `git --help ...` is converted internally into `git
 202help ...`.
 203
 204--exec-path::
 205        Path to wherever your core git programs are installed.
 206        This can also be controlled by setting the GIT_EXEC_PATH
 207        environment variable. If no path is given, 'git' will print
 208        the current setting and then exit.
 209
 210--html-path::
 211        Print the path to wherever your git HTML documentation is installed
 212        and exit.
 213
 214-p::
 215--paginate::
 216        Pipe all output into 'less' (or if set, $PAGER).
 217
 218--no-pager::
 219        Do not pipe git output into a pager.
 220
 221--git-dir=<path>::
 222        Set the path to the repository. This can also be controlled by
 223        setting the GIT_DIR environment variable. It can be an absolute
 224        path or relative path to current working directory.
 225
 226--work-tree=<path>::
 227        Set the path to the working tree.  The value will not be
 228        used in combination with repositories found automatically in
 229        a .git directory (i.e. $GIT_DIR is not set).
 230        This can also be controlled by setting the GIT_WORK_TREE
 231        environment variable and the core.worktree configuration
 232        variable. It can be an absolute path or relative path to
 233        the directory specified by --git-dir or GIT_DIR.
 234        Note: If --git-dir or GIT_DIR are specified but none of
 235        --work-tree, GIT_WORK_TREE and core.worktree is specified,
 236        the current working directory is regarded as the top directory
 237        of your working tree.
 238
 239--bare::
 240        Treat the repository as a bare repository.  If GIT_DIR
 241        environment is not set, it is set to the current working
 242        directory.
 243
 244
 245FURTHER DOCUMENTATION
 246---------------------
 247
 248See the references above to get started using git.  The following is
 249probably more detail than necessary for a first-time user.
 250
 251The link:user-manual.html#git-concepts[git concepts chapter of the
 252user-manual] and linkgit:gitcore-tutorial[7] both provide
 253introductions to the underlying git architecture.
 254
 255See linkgit:gitworkflows[7] for an overview of recommended workflows.
 256
 257See also the link:howto-index.html[howto] documents for some useful
 258examples.
 259
 260The internals are documented in the
 261link:technical/api-index.html[GIT API documentation].
 262
 263GIT COMMANDS
 264------------
 265
 266We divide git into high level ("porcelain") commands and low level
 267("plumbing") commands.
 268
 269High-level commands (porcelain)
 270-------------------------------
 271
 272We separate the porcelain commands into the main commands and some
 273ancillary user utilities.
 274
 275Main porcelain commands
 276~~~~~~~~~~~~~~~~~~~~~~~
 277
 278include::cmds-mainporcelain.txt[]
 279
 280Ancillary Commands
 281~~~~~~~~~~~~~~~~~~
 282Manipulators:
 283
 284include::cmds-ancillarymanipulators.txt[]
 285
 286Interrogators:
 287
 288include::cmds-ancillaryinterrogators.txt[]
 289
 290
 291Interacting with Others
 292~~~~~~~~~~~~~~~~~~~~~~~
 293
 294These commands are to interact with foreign SCM and with other
 295people via patch over e-mail.
 296
 297include::cmds-foreignscminterface.txt[]
 298
 299
 300Low-level commands (plumbing)
 301-----------------------------
 302
 303Although git includes its
 304own porcelain layer, its low-level commands are sufficient to support
 305development of alternative porcelains.  Developers of such porcelains
 306might start by reading about linkgit:git-update-index[1] and
 307linkgit:git-read-tree[1].
 308
 309The interface (input, output, set of options and the semantics)
 310to these low-level commands are meant to be a lot more stable
 311than Porcelain level commands, because these commands are
 312primarily for scripted use.  The interface to Porcelain commands
 313on the other hand are subject to change in order to improve the
 314end user experience.
 315
 316The following description divides
 317the low-level commands into commands that manipulate objects (in
 318the repository, index, and working tree), commands that interrogate and
 319compare objects, and commands that move objects and references between
 320repositories.
 321
 322
 323Manipulation commands
 324~~~~~~~~~~~~~~~~~~~~~
 325
 326include::cmds-plumbingmanipulators.txt[]
 327
 328
 329Interrogation commands
 330~~~~~~~~~~~~~~~~~~~~~~
 331
 332include::cmds-plumbinginterrogators.txt[]
 333
 334In general, the interrogate commands do not touch the files in
 335the working tree.
 336
 337
 338Synching repositories
 339~~~~~~~~~~~~~~~~~~~~~
 340
 341include::cmds-synchingrepositories.txt[]
 342
 343The following are helper commands used by the above; end users
 344typically do not use them directly.
 345
 346include::cmds-synchelpers.txt[]
 347
 348
 349Internal helper commands
 350~~~~~~~~~~~~~~~~~~~~~~~~
 351
 352These are internal helper commands used by other commands; end
 353users typically do not use them directly.
 354
 355include::cmds-purehelpers.txt[]
 356
 357
 358Configuration Mechanism
 359-----------------------
 360
 361Starting from 0.99.9 (actually mid 0.99.8.GIT), `.git/config` file
 362is used to hold per-repository configuration options.  It is a
 363simple text file modeled after `.ini` format familiar to some
 364people.  Here is an example:
 365
 366------------
 367#
 368# A '#' or ';' character indicates a comment.
 369#
 370
 371; core variables
 372[core]
 373        ; Don't trust file modes
 374        filemode = false
 375
 376; user identity
 377[user]
 378        name = "Junio C Hamano"
 379        email = "junkio@twinsun.com"
 380
 381------------
 382
 383Various commands read from the configuration file and adjust
 384their operation accordingly.
 385
 386
 387Identifier Terminology
 388----------------------
 389<object>::
 390        Indicates the object name for any type of object.
 391
 392<blob>::
 393        Indicates a blob object name.
 394
 395<tree>::
 396        Indicates a tree object name.
 397
 398<commit>::
 399        Indicates a commit object name.
 400
 401<tree-ish>::
 402        Indicates a tree, commit or tag object name.  A
 403        command that takes a <tree-ish> argument ultimately wants to
 404        operate on a <tree> object but automatically dereferences
 405        <commit> and <tag> objects that point at a <tree>.
 406
 407<commit-ish>::
 408        Indicates a commit or tag object name.  A
 409        command that takes a <commit-ish> argument ultimately wants to
 410        operate on a <commit> object but automatically dereferences
 411        <tag> objects that point at a <commit>.
 412
 413<type>::
 414        Indicates that an object type is required.
 415        Currently one of: `blob`, `tree`, `commit`, or `tag`.
 416
 417<file>::
 418        Indicates a filename - almost always relative to the
 419        root of the tree structure `GIT_INDEX_FILE` describes.
 420
 421Symbolic Identifiers
 422--------------------
 423Any git command accepting any <object> can also use the following
 424symbolic notation:
 425
 426HEAD::
 427        indicates the head of the current branch (i.e. the
 428        contents of `$GIT_DIR/HEAD`).
 429
 430<tag>::
 431        a valid tag 'name'
 432        (i.e. the contents of `$GIT_DIR/refs/tags/<tag>`).
 433
 434<head>::
 435        a valid head 'name'
 436        (i.e. the contents of `$GIT_DIR/refs/heads/<head>`).
 437
 438For a more complete list of ways to spell object names, see
 439"SPECIFYING REVISIONS" section in linkgit:git-rev-parse[1].
 440
 441
 442File/Directory Structure
 443------------------------
 444
 445Please see the linkgit:gitrepository-layout[5] document.
 446
 447Read linkgit:githooks[5] for more details about each hook.
 448
 449Higher level SCMs may provide and manage additional information in the
 450`$GIT_DIR`.
 451
 452
 453Terminology
 454-----------
 455Please see linkgit:gitglossary[7].
 456
 457
 458Environment Variables
 459---------------------
 460Various git commands use the following environment variables:
 461
 462The git Repository
 463~~~~~~~~~~~~~~~~~~
 464These environment variables apply to 'all' core git commands. Nb: it
 465is worth noting that they may be used/overridden by SCMS sitting above
 466git so take care if using Cogito etc.
 467
 468'GIT_INDEX_FILE'::
 469        This environment allows the specification of an alternate
 470        index file. If not specified, the default of `$GIT_DIR/index`
 471        is used.
 472
 473'GIT_OBJECT_DIRECTORY'::
 474        If the object storage directory is specified via this
 475        environment variable then the sha1 directories are created
 476        underneath - otherwise the default `$GIT_DIR/objects`
 477        directory is used.
 478
 479'GIT_ALTERNATE_OBJECT_DIRECTORIES'::
 480        Due to the immutable nature of git objects, old objects can be
 481        archived into shared, read-only directories. This variable
 482        specifies a ":" separated (on Windows ";" separated) list
 483        of git object directories which can be used to search for git
 484        objects. New objects will not be written to these directories.
 485
 486'GIT_DIR'::
 487        If the 'GIT_DIR' environment variable is set then it
 488        specifies a path to use instead of the default `.git`
 489        for the base of the repository.
 490
 491'GIT_WORK_TREE'::
 492        Set the path to the working tree.  The value will not be
 493        used in combination with repositories found automatically in
 494        a .git directory (i.e. $GIT_DIR is not set).
 495        This can also be controlled by the '--work-tree' command line
 496        option and the core.worktree configuration variable.
 497
 498'GIT_CEILING_DIRECTORIES'::
 499        This should be a colon-separated list of absolute paths.
 500        If set, it is a list of directories that git should not chdir
 501        up into while looking for a repository directory.
 502        It will not exclude the current working directory or
 503        a GIT_DIR set on the command line or in the environment.
 504        (Useful for excluding slow-loading network directories.)
 505
 506git Commits
 507~~~~~~~~~~~
 508'GIT_AUTHOR_NAME'::
 509'GIT_AUTHOR_EMAIL'::
 510'GIT_AUTHOR_DATE'::
 511'GIT_COMMITTER_NAME'::
 512'GIT_COMMITTER_EMAIL'::
 513'GIT_COMMITTER_DATE'::
 514'EMAIL'::
 515        see linkgit:git-commit-tree[1]
 516
 517git Diffs
 518~~~~~~~~~
 519'GIT_DIFF_OPTS'::
 520        Only valid setting is "--unified=??" or "-u??" to set the
 521        number of context lines shown when a unified diff is created.
 522        This takes precedence over any "-U" or "--unified" option
 523        value passed on the git diff command line.
 524
 525'GIT_EXTERNAL_DIFF'::
 526        When the environment variable 'GIT_EXTERNAL_DIFF' is set, the
 527        program named by it is called, instead of the diff invocation
 528        described above.  For a path that is added, removed, or modified,
 529        'GIT_EXTERNAL_DIFF' is called with 7 parameters:
 530
 531        path old-file old-hex old-mode new-file new-hex new-mode
 532+
 533where:
 534
 535        <old|new>-file:: are files GIT_EXTERNAL_DIFF can use to read the
 536                         contents of <old|new>,
 537        <old|new>-hex:: are the 40-hexdigit SHA1 hashes,
 538        <old|new>-mode:: are the octal representation of the file modes.
 539
 540+
 541The file parameters can point at the user's working file
 542(e.g. `new-file` in "git-diff-files"), `/dev/null` (e.g. `old-file`
 543when a new file is added), or a temporary file (e.g. `old-file` in the
 544index).  'GIT_EXTERNAL_DIFF' should not worry about unlinking the
 545temporary file --- it is removed when 'GIT_EXTERNAL_DIFF' exits.
 546+
 547For a path that is unmerged, 'GIT_EXTERNAL_DIFF' is called with 1
 548parameter, <path>.
 549
 550other
 551~~~~~
 552'GIT_MERGE_VERBOSITY'::
 553        A number controlling the amount of output shown by
 554        the recursive merge strategy.  Overrides merge.verbosity.
 555        See linkgit:git-merge[1]
 556
 557'GIT_PAGER'::
 558        This environment variable overrides `$PAGER`. If it is set
 559        to an empty string or to the value "cat", git will not launch
 560        a pager.  See also the `core.pager` option in
 561        linkgit:git-config[1].
 562
 563'GIT_SSH'::
 564        If this environment variable is set then 'git-fetch'
 565        and 'git-push' will use this command instead
 566        of 'ssh' when they need to connect to a remote system.
 567        The '$GIT_SSH' command will be given exactly two arguments:
 568        the 'username@host' (or just 'host') from the URL and the
 569        shell command to execute on that remote system.
 570+
 571To pass options to the program that you want to list in GIT_SSH
 572you will need to wrap the program and options into a shell script,
 573then set GIT_SSH to refer to the shell script.
 574+
 575Usually it is easier to configure any desired options through your
 576personal `.ssh/config` file.  Please consult your ssh documentation
 577for further details.
 578
 579'GIT_FLUSH'::
 580        If this environment variable is set to "1", then commands such
 581        as 'git-blame' (in incremental mode), 'git-rev-list', 'git-log',
 582        and 'git-whatchanged' will force a flush of the output stream
 583        after each commit-oriented record have been flushed.   If this
 584        variable is set to "0", the output of these commands will be done
 585        using completely buffered I/O.   If this environment variable is
 586        not set, git will choose buffered or record-oriented flushing
 587        based on whether stdout appears to be redirected to a file or not.
 588
 589'GIT_TRACE'::
 590        If this variable is set to "1", "2" or "true" (comparison
 591        is case insensitive), git will print `trace:` messages on
 592        stderr telling about alias expansion, built-in command
 593        execution and external command execution.
 594        If this variable is set to an integer value greater than 1
 595        and lower than 10 (strictly) then git will interpret this
 596        value as an open file descriptor and will try to write the
 597        trace messages into this file descriptor.
 598        Alternatively, if this variable is set to an absolute path
 599        (starting with a '/' character), git will interpret this
 600        as a file path and will try to write the trace messages
 601        into it.
 602
 603Discussion[[Discussion]]
 604------------------------
 605
 606More detail on the following is available from the
 607link:user-manual.html#git-concepts[git concepts chapter of the
 608user-manual] and linkgit:gitcore-tutorial[7].
 609
 610A git project normally consists of a working directory with a ".git"
 611subdirectory at the top level.  The .git directory contains, among other
 612things, a compressed object database representing the complete history
 613of the project, an "index" file which links that history to the current
 614contents of the working tree, and named pointers into that history such
 615as tags and branch heads.
 616
 617The object database contains objects of three main types: blobs, which
 618hold file data; trees, which point to blobs and other trees to build up
 619directory hierarchies; and commits, which each reference a single tree
 620and some number of parent commits.
 621
 622The commit, equivalent to what other systems call a "changeset" or
 623"version", represents a step in the project's history, and each parent
 624represents an immediately preceding step.  Commits with more than one
 625parent represent merges of independent lines of development.
 626
 627All objects are named by the SHA1 hash of their contents, normally
 628written as a string of 40 hex digits.  Such names are globally unique.
 629The entire history leading up to a commit can be vouched for by signing
 630just that commit.  A fourth object type, the tag, is provided for this
 631purpose.
 632
 633When first created, objects are stored in individual files, but for
 634efficiency may later be compressed together into "pack files".
 635
 636Named pointers called refs mark interesting points in history.  A ref
 637may contain the SHA1 name of an object or the name of another ref.  Refs
 638with names beginning `ref/head/` contain the SHA1 name of the most
 639recent commit (or "head") of a branch under development.  SHA1 names of
 640tags of interest are stored under `ref/tags/`.  A special ref named
 641`HEAD` contains the name of the currently checked-out branch.
 642
 643The index file is initialized with a list of all paths and, for each
 644path, a blob object and a set of attributes.  The blob object represents
 645the contents of the file as of the head of the current branch.  The
 646attributes (last modified time, size, etc.) are taken from the
 647corresponding file in the working tree.  Subsequent changes to the
 648working tree can be found by comparing these attributes.  The index may
 649be updated with new content, and new commits may be created from the
 650content stored in the index.
 651
 652The index is also capable of storing multiple entries (called "stages")
 653for a given pathname.  These stages are used to hold the various
 654unmerged version of a file when a merge is in progress.
 655
 656Authors
 657-------
 658* git's founding father is Linus Torvalds <torvalds@osdl.org>.
 659* The current git nurse is Junio C Hamano <gitster@pobox.com>.
 660* The git potty was written by Andreas Ericsson <ae@op5.se>.
 661* General upbringing is handled by the git-list <git@vger.kernel.org>.
 662
 663Documentation
 664--------------
 665The documentation for git suite was started by David Greaves
 666<david@dgreaves.com>, and later enhanced greatly by the
 667contributors on the git-list <git@vger.kernel.org>.
 668
 669SEE ALSO
 670--------
 671linkgit:gittutorial[7], linkgit:gittutorial-2[7],
 672link:everyday.html[Everyday Git], linkgit:gitcvs-migration[7],
 673linkgit:gitglossary[7], linkgit:gitcore-tutorial[7],
 674linkgit:gitcli[7], link:user-manual.html[The Git User's Manual],
 675linkgit:gitworkflows[7]
 676
 677GIT
 678---
 679Part of the linkgit:git[1] suite