Documentation / git.txton commit Merge branch 'il/rev-glob' (80eac92)
   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:v1.6.6.1/git.html[documentation for release 1.6.6.1]
  47
  48* release notes for
  49  link:RelNotes-1.6.6.1.txt[1.6.6.1],
  50  link:RelNotes-1.6.6.txt[1.6.6].
  51
  52* link:v1.6.5.8/git.html[documentation for release 1.6.5.8]
  53
  54* release notes for
  55  link:RelNotes-1.6.5.8.txt[1.6.5.8],
  56  link:RelNotes-1.6.5.7.txt[1.6.5.7],
  57  link:RelNotes-1.6.5.6.txt[1.6.5.6],
  58  link:RelNotes-1.6.5.5.txt[1.6.5.5],
  59  link:RelNotes-1.6.5.4.txt[1.6.5.4],
  60  link:RelNotes-1.6.5.3.txt[1.6.5.3],
  61  link:RelNotes-1.6.5.2.txt[1.6.5.2],
  62  link:RelNotes-1.6.5.1.txt[1.6.5.1],
  63  link:RelNotes-1.6.5.txt[1.6.5].
  64
  65* link:v1.6.4.4/git.html[documentation for release 1.6.4.4]
  66
  67* release notes for
  68  link:RelNotes-1.6.4.4.txt[1.6.4.4],
  69  link:RelNotes-1.6.4.3.txt[1.6.4.3],
  70  link:RelNotes-1.6.4.2.txt[1.6.4.2],
  71  link:RelNotes-1.6.4.1.txt[1.6.4.1],
  72  link:RelNotes-1.6.4.txt[1.6.4].
  73
  74* link:v1.6.3.4/git.html[documentation for release 1.6.3.4]
  75
  76* release notes for
  77  link:RelNotes-1.6.3.4.txt[1.6.3.4],
  78  link:RelNotes-1.6.3.3.txt[1.6.3.3],
  79  link:RelNotes-1.6.3.2.txt[1.6.3.2],
  80  link:RelNotes-1.6.3.1.txt[1.6.3.1],
  81  link:RelNotes-1.6.3.txt[1.6.3].
  82
  83* release notes for
  84  link:RelNotes-1.6.2.5.txt[1.6.2.5],
  85  link:RelNotes-1.6.2.4.txt[1.6.2.4],
  86  link:RelNotes-1.6.2.3.txt[1.6.2.3],
  87  link:RelNotes-1.6.2.2.txt[1.6.2.2],
  88  link:RelNotes-1.6.2.1.txt[1.6.2.1],
  89  link:RelNotes-1.6.2.txt[1.6.2].
  90
  91* link:v1.6.1.3/git.html[documentation for release 1.6.1.3]
  92
  93* release notes for
  94  link:RelNotes-1.6.1.3.txt[1.6.1.3],
  95  link:RelNotes-1.6.1.2.txt[1.6.1.2],
  96  link:RelNotes-1.6.1.1.txt[1.6.1.1],
  97  link:RelNotes-1.6.1.txt[1.6.1].
  98
  99* link:v1.6.0.6/git.html[documentation for release 1.6.0.6]
 100
 101* release notes for
 102  link:RelNotes-1.6.0.6.txt[1.6.0.6],
 103  link:RelNotes-1.6.0.5.txt[1.6.0.5],
 104  link:RelNotes-1.6.0.4.txt[1.6.0.4],
 105  link:RelNotes-1.6.0.3.txt[1.6.0.3],
 106  link:RelNotes-1.6.0.2.txt[1.6.0.2],
 107  link:RelNotes-1.6.0.1.txt[1.6.0.1],
 108  link:RelNotes-1.6.0.txt[1.6.0].
 109
 110* link:v1.5.6.6/git.html[documentation for release 1.5.6.6]
 111
 112* release notes for
 113  link:RelNotes-1.5.6.6.txt[1.5.6.6],
 114  link:RelNotes-1.5.6.5.txt[1.5.6.5],
 115  link:RelNotes-1.5.6.4.txt[1.5.6.4],
 116  link:RelNotes-1.5.6.3.txt[1.5.6.3],
 117  link:RelNotes-1.5.6.2.txt[1.5.6.2],
 118  link:RelNotes-1.5.6.1.txt[1.5.6.1],
 119  link:RelNotes-1.5.6.txt[1.5.6].
 120
 121* link:v1.5.5.6/git.html[documentation for release 1.5.5.6]
 122
 123* release notes for
 124  link:RelNotes-1.5.5.6.txt[1.5.5.6],
 125  link:RelNotes-1.5.5.5.txt[1.5.5.5],
 126  link:RelNotes-1.5.5.4.txt[1.5.5.4],
 127  link:RelNotes-1.5.5.3.txt[1.5.5.3],
 128  link:RelNotes-1.5.5.2.txt[1.5.5.2],
 129  link:RelNotes-1.5.5.1.txt[1.5.5.1],
 130  link:RelNotes-1.5.5.txt[1.5.5].
 131
 132* link:v1.5.4.7/git.html[documentation for release 1.5.4.7]
 133
 134* release notes for
 135  link:RelNotes-1.5.4.7.txt[1.5.4.7],
 136  link:RelNotes-1.5.4.6.txt[1.5.4.6],
 137  link:RelNotes-1.5.4.5.txt[1.5.4.5],
 138  link:RelNotes-1.5.4.4.txt[1.5.4.4],
 139  link:RelNotes-1.5.4.3.txt[1.5.4.3],
 140  link:RelNotes-1.5.4.2.txt[1.5.4.2],
 141  link:RelNotes-1.5.4.1.txt[1.5.4.1],
 142  link:RelNotes-1.5.4.txt[1.5.4].
 143
 144* link:v1.5.3.8/git.html[documentation for release 1.5.3.8]
 145
 146* release notes for
 147  link:RelNotes-1.5.3.8.txt[1.5.3.8],
 148  link:RelNotes-1.5.3.7.txt[1.5.3.7],
 149  link:RelNotes-1.5.3.6.txt[1.5.3.6],
 150  link:RelNotes-1.5.3.5.txt[1.5.3.5],
 151  link:RelNotes-1.5.3.4.txt[1.5.3.4],
 152  link:RelNotes-1.5.3.3.txt[1.5.3.3],
 153  link:RelNotes-1.5.3.2.txt[1.5.3.2],
 154  link:RelNotes-1.5.3.1.txt[1.5.3.1],
 155  link:RelNotes-1.5.3.txt[1.5.3].
 156
 157* link:v1.5.2.5/git.html[documentation for release 1.5.2.5]
 158
 159* release notes for
 160  link:RelNotes-1.5.2.5.txt[1.5.2.5],
 161  link:RelNotes-1.5.2.4.txt[1.5.2.4],
 162  link:RelNotes-1.5.2.3.txt[1.5.2.3],
 163  link:RelNotes-1.5.2.2.txt[1.5.2.2],
 164  link:RelNotes-1.5.2.1.txt[1.5.2.1],
 165  link:RelNotes-1.5.2.txt[1.5.2].
 166
 167* link:v1.5.1.6/git.html[documentation for release 1.5.1.6]
 168
 169* release notes for
 170  link:RelNotes-1.5.1.6.txt[1.5.1.6],
 171  link:RelNotes-1.5.1.5.txt[1.5.1.5],
 172  link:RelNotes-1.5.1.4.txt[1.5.1.4],
 173  link:RelNotes-1.5.1.3.txt[1.5.1.3],
 174  link:RelNotes-1.5.1.2.txt[1.5.1.2],
 175  link:RelNotes-1.5.1.1.txt[1.5.1.1],
 176  link:RelNotes-1.5.1.txt[1.5.1].
 177
 178* link:v1.5.0.7/git.html[documentation for release 1.5.0.7]
 179
 180* release notes for
 181  link:RelNotes-1.5.0.7.txt[1.5.0.7],
 182  link:RelNotes-1.5.0.6.txt[1.5.0.6],
 183  link:RelNotes-1.5.0.5.txt[1.5.0.5],
 184  link:RelNotes-1.5.0.3.txt[1.5.0.3],
 185  link:RelNotes-1.5.0.2.txt[1.5.0.2],
 186  link:RelNotes-1.5.0.1.txt[1.5.0.1],
 187  link:RelNotes-1.5.0.txt[1.5.0].
 188
 189* documentation for release link:v1.4.4.4/git.html[1.4.4.4],
 190  link:v1.3.3/git.html[1.3.3],
 191  link:v1.2.6/git.html[1.2.6],
 192  link:v1.0.13/git.html[1.0.13].
 193
 194============
 195
 196endif::stalenotes[]
 197
 198OPTIONS
 199-------
 200--version::
 201        Prints the git suite version that the 'git' program came from.
 202
 203--help::
 204        Prints the synopsis and a list of the most commonly used
 205        commands. If the option '--all' or '-a' is given then all
 206        available commands are printed. If a git command is named this
 207        option will bring up the manual page for that command.
 208+
 209Other options are available to control how the manual page is
 210displayed. See linkgit:git-help[1] for more information,
 211because `git --help ...` is converted internally into `git
 212help ...`.
 213
 214--exec-path::
 215        Path to wherever your core git programs are installed.
 216        This can also be controlled by setting the GIT_EXEC_PATH
 217        environment variable. If no path is given, 'git' will print
 218        the current setting and then exit.
 219
 220--html-path::
 221        Print the path to wherever your git HTML documentation is installed
 222        and exit.
 223
 224-p::
 225--paginate::
 226        Pipe all output into 'less' (or if set, $PAGER).
 227
 228--no-pager::
 229        Do not pipe git output into a pager.
 230
 231--git-dir=<path>::
 232        Set the path to the repository. This can also be controlled by
 233        setting the GIT_DIR environment variable. It can be an absolute
 234        path or relative path to current working directory.
 235
 236--work-tree=<path>::
 237        Set the path to the working tree.  The value will not be
 238        used in combination with repositories found automatically in
 239        a .git directory (i.e. $GIT_DIR is not set).
 240        This can also be controlled by setting the GIT_WORK_TREE
 241        environment variable and the core.worktree configuration
 242        variable. It can be an absolute path or relative path to
 243        the directory specified by --git-dir or GIT_DIR.
 244        Note: If --git-dir or GIT_DIR are specified but none of
 245        --work-tree, GIT_WORK_TREE and core.worktree is specified,
 246        the current working directory is regarded as the top directory
 247        of your working tree.
 248
 249--bare::
 250        Treat the repository as a bare repository.  If GIT_DIR
 251        environment is not set, it is set to the current working
 252        directory.
 253
 254--no-replace-objects::
 255        Do not use replacement refs to replace git objects. See
 256        linkgit:git-replace[1] for more information.
 257
 258
 259FURTHER DOCUMENTATION
 260---------------------
 261
 262See the references above to get started using git.  The following is
 263probably more detail than necessary for a first-time user.
 264
 265The link:user-manual.html#git-concepts[git concepts chapter of the
 266user-manual] and linkgit:gitcore-tutorial[7] both provide
 267introductions to the underlying git architecture.
 268
 269See linkgit:gitworkflows[7] for an overview of recommended workflows.
 270
 271See also the link:howto-index.html[howto] documents for some useful
 272examples.
 273
 274The internals are documented in the
 275link:technical/api-index.html[GIT API documentation].
 276
 277GIT COMMANDS
 278------------
 279
 280We divide git into high level ("porcelain") commands and low level
 281("plumbing") commands.
 282
 283High-level commands (porcelain)
 284-------------------------------
 285
 286We separate the porcelain commands into the main commands and some
 287ancillary user utilities.
 288
 289Main porcelain commands
 290~~~~~~~~~~~~~~~~~~~~~~~
 291
 292include::cmds-mainporcelain.txt[]
 293
 294Ancillary Commands
 295~~~~~~~~~~~~~~~~~~
 296Manipulators:
 297
 298include::cmds-ancillarymanipulators.txt[]
 299
 300Interrogators:
 301
 302include::cmds-ancillaryinterrogators.txt[]
 303
 304
 305Interacting with Others
 306~~~~~~~~~~~~~~~~~~~~~~~
 307
 308These commands are to interact with foreign SCM and with other
 309people via patch over e-mail.
 310
 311include::cmds-foreignscminterface.txt[]
 312
 313
 314Low-level commands (plumbing)
 315-----------------------------
 316
 317Although git includes its
 318own porcelain layer, its low-level commands are sufficient to support
 319development of alternative porcelains.  Developers of such porcelains
 320might start by reading about linkgit:git-update-index[1] and
 321linkgit:git-read-tree[1].
 322
 323The interface (input, output, set of options and the semantics)
 324to these low-level commands are meant to be a lot more stable
 325than Porcelain level commands, because these commands are
 326primarily for scripted use.  The interface to Porcelain commands
 327on the other hand are subject to change in order to improve the
 328end user experience.
 329
 330The following description divides
 331the low-level commands into commands that manipulate objects (in
 332the repository, index, and working tree), commands that interrogate and
 333compare objects, and commands that move objects and references between
 334repositories.
 335
 336
 337Manipulation commands
 338~~~~~~~~~~~~~~~~~~~~~
 339
 340include::cmds-plumbingmanipulators.txt[]
 341
 342
 343Interrogation commands
 344~~~~~~~~~~~~~~~~~~~~~~
 345
 346include::cmds-plumbinginterrogators.txt[]
 347
 348In general, the interrogate commands do not touch the files in
 349the working tree.
 350
 351
 352Synching repositories
 353~~~~~~~~~~~~~~~~~~~~~
 354
 355include::cmds-synchingrepositories.txt[]
 356
 357The following are helper commands used by the above; end users
 358typically do not use them directly.
 359
 360include::cmds-synchelpers.txt[]
 361
 362
 363Internal helper commands
 364~~~~~~~~~~~~~~~~~~~~~~~~
 365
 366These are internal helper commands used by other commands; end
 367users typically do not use them directly.
 368
 369include::cmds-purehelpers.txt[]
 370
 371
 372Configuration Mechanism
 373-----------------------
 374
 375Starting from 0.99.9 (actually mid 0.99.8.GIT), `.git/config` file
 376is used to hold per-repository configuration options.  It is a
 377simple text file modeled after `.ini` format familiar to some
 378people.  Here is an example:
 379
 380------------
 381#
 382# A '#' or ';' character indicates a comment.
 383#
 384
 385; core variables
 386[core]
 387        ; Don't trust file modes
 388        filemode = false
 389
 390; user identity
 391[user]
 392        name = "Junio C Hamano"
 393        email = "junkio@twinsun.com"
 394
 395------------
 396
 397Various commands read from the configuration file and adjust
 398their operation accordingly.
 399
 400
 401Identifier Terminology
 402----------------------
 403<object>::
 404        Indicates the object name for any type of object.
 405
 406<blob>::
 407        Indicates a blob object name.
 408
 409<tree>::
 410        Indicates a tree object name.
 411
 412<commit>::
 413        Indicates a commit object name.
 414
 415<tree-ish>::
 416        Indicates a tree, commit or tag object name.  A
 417        command that takes a <tree-ish> argument ultimately wants to
 418        operate on a <tree> object but automatically dereferences
 419        <commit> and <tag> objects that point at a <tree>.
 420
 421<commit-ish>::
 422        Indicates a commit or tag object name.  A
 423        command that takes a <commit-ish> argument ultimately wants to
 424        operate on a <commit> object but automatically dereferences
 425        <tag> objects that point at a <commit>.
 426
 427<type>::
 428        Indicates that an object type is required.
 429        Currently one of: `blob`, `tree`, `commit`, or `tag`.
 430
 431<file>::
 432        Indicates a filename - almost always relative to the
 433        root of the tree structure `GIT_INDEX_FILE` describes.
 434
 435Symbolic Identifiers
 436--------------------
 437Any git command accepting any <object> can also use the following
 438symbolic notation:
 439
 440HEAD::
 441        indicates the head of the current branch (i.e. the
 442        contents of `$GIT_DIR/HEAD`).
 443
 444<tag>::
 445        a valid tag 'name'
 446        (i.e. the contents of `$GIT_DIR/refs/tags/<tag>`).
 447
 448<head>::
 449        a valid head 'name'
 450        (i.e. the contents of `$GIT_DIR/refs/heads/<head>`).
 451
 452For a more complete list of ways to spell object names, see
 453"SPECIFYING REVISIONS" section in linkgit:git-rev-parse[1].
 454
 455
 456File/Directory Structure
 457------------------------
 458
 459Please see the linkgit:gitrepository-layout[5] document.
 460
 461Read linkgit:githooks[5] for more details about each hook.
 462
 463Higher level SCMs may provide and manage additional information in the
 464`$GIT_DIR`.
 465
 466
 467Terminology
 468-----------
 469Please see linkgit:gitglossary[7].
 470
 471
 472Environment Variables
 473---------------------
 474Various git commands use the following environment variables:
 475
 476The git Repository
 477~~~~~~~~~~~~~~~~~~
 478These environment variables apply to 'all' core git commands. Nb: it
 479is worth noting that they may be used/overridden by SCMS sitting above
 480git so take care if using Cogito etc.
 481
 482'GIT_INDEX_FILE'::
 483        This environment allows the specification of an alternate
 484        index file. If not specified, the default of `$GIT_DIR/index`
 485        is used.
 486
 487'GIT_OBJECT_DIRECTORY'::
 488        If the object storage directory is specified via this
 489        environment variable then the sha1 directories are created
 490        underneath - otherwise the default `$GIT_DIR/objects`
 491        directory is used.
 492
 493'GIT_ALTERNATE_OBJECT_DIRECTORIES'::
 494        Due to the immutable nature of git objects, old objects can be
 495        archived into shared, read-only directories. This variable
 496        specifies a ":" separated (on Windows ";" separated) list
 497        of git object directories which can be used to search for git
 498        objects. New objects will not be written to these directories.
 499
 500'GIT_DIR'::
 501        If the 'GIT_DIR' environment variable is set then it
 502        specifies a path to use instead of the default `.git`
 503        for the base of the repository.
 504
 505'GIT_WORK_TREE'::
 506        Set the path to the working tree.  The value will not be
 507        used in combination with repositories found automatically in
 508        a .git directory (i.e. $GIT_DIR is not set).
 509        This can also be controlled by the '--work-tree' command line
 510        option and the core.worktree configuration variable.
 511
 512'GIT_CEILING_DIRECTORIES'::
 513        This should be a colon-separated list of absolute paths.
 514        If set, it is a list of directories that git should not chdir
 515        up into while looking for a repository directory.
 516        It will not exclude the current working directory or
 517        a GIT_DIR set on the command line or in the environment.
 518        (Useful for excluding slow-loading network directories.)
 519
 520git Commits
 521~~~~~~~~~~~
 522'GIT_AUTHOR_NAME'::
 523'GIT_AUTHOR_EMAIL'::
 524'GIT_AUTHOR_DATE'::
 525'GIT_COMMITTER_NAME'::
 526'GIT_COMMITTER_EMAIL'::
 527'GIT_COMMITTER_DATE'::
 528'EMAIL'::
 529        see linkgit:git-commit-tree[1]
 530
 531git Diffs
 532~~~~~~~~~
 533'GIT_DIFF_OPTS'::
 534        Only valid setting is "--unified=??" or "-u??" to set the
 535        number of context lines shown when a unified diff is created.
 536        This takes precedence over any "-U" or "--unified" option
 537        value passed on the git diff command line.
 538
 539'GIT_EXTERNAL_DIFF'::
 540        When the environment variable 'GIT_EXTERNAL_DIFF' is set, the
 541        program named by it is called, instead of the diff invocation
 542        described above.  For a path that is added, removed, or modified,
 543        'GIT_EXTERNAL_DIFF' is called with 7 parameters:
 544
 545        path old-file old-hex old-mode new-file new-hex new-mode
 546+
 547where:
 548
 549        <old|new>-file:: are files GIT_EXTERNAL_DIFF can use to read the
 550                         contents of <old|new>,
 551        <old|new>-hex:: are the 40-hexdigit SHA1 hashes,
 552        <old|new>-mode:: are the octal representation of the file modes.
 553
 554+
 555The file parameters can point at the user's working file
 556(e.g. `new-file` in "git-diff-files"), `/dev/null` (e.g. `old-file`
 557when a new file is added), or a temporary file (e.g. `old-file` in the
 558index).  'GIT_EXTERNAL_DIFF' should not worry about unlinking the
 559temporary file --- it is removed when 'GIT_EXTERNAL_DIFF' exits.
 560+
 561For a path that is unmerged, 'GIT_EXTERNAL_DIFF' is called with 1
 562parameter, <path>.
 563
 564other
 565~~~~~
 566'GIT_MERGE_VERBOSITY'::
 567        A number controlling the amount of output shown by
 568        the recursive merge strategy.  Overrides merge.verbosity.
 569        See linkgit:git-merge[1]
 570
 571'GIT_PAGER'::
 572        This environment variable overrides `$PAGER`. If it is set
 573        to an empty string or to the value "cat", git will not launch
 574        a pager.  See also the `core.pager` option in
 575        linkgit:git-config[1].
 576
 577'GIT_SSH'::
 578        If this environment variable is set then 'git fetch'
 579        and 'git push' will use this command instead
 580        of 'ssh' when they need to connect to a remote system.
 581        The '$GIT_SSH' command will be given exactly two arguments:
 582        the 'username@host' (or just 'host') from the URL and the
 583        shell command to execute on that remote system.
 584+
 585To pass options to the program that you want to list in GIT_SSH
 586you will need to wrap the program and options into a shell script,
 587then set GIT_SSH to refer to the shell script.
 588+
 589Usually it is easier to configure any desired options through your
 590personal `.ssh/config` file.  Please consult your ssh documentation
 591for further details.
 592
 593'GIT_FLUSH'::
 594        If this environment variable is set to "1", then commands such
 595        as 'git blame' (in incremental mode), 'git rev-list', 'git log',
 596        and 'git whatchanged' will force a flush of the output stream
 597        after each commit-oriented record have been flushed.   If this
 598        variable is set to "0", the output of these commands will be done
 599        using completely buffered I/O.   If this environment variable is
 600        not set, git will choose buffered or record-oriented flushing
 601        based on whether stdout appears to be redirected to a file or not.
 602
 603'GIT_TRACE'::
 604        If this variable is set to "1", "2" or "true" (comparison
 605        is case insensitive), git will print `trace:` messages on
 606        stderr telling about alias expansion, built-in command
 607        execution and external command execution.
 608        If this variable is set to an integer value greater than 1
 609        and lower than 10 (strictly) then git will interpret this
 610        value as an open file descriptor and will try to write the
 611        trace messages into this file descriptor.
 612        Alternatively, if this variable is set to an absolute path
 613        (starting with a '/' character), git will interpret this
 614        as a file path and will try to write the trace messages
 615        into it.
 616
 617Discussion[[Discussion]]
 618------------------------
 619
 620More detail on the following is available from the
 621link:user-manual.html#git-concepts[git concepts chapter of the
 622user-manual] and linkgit:gitcore-tutorial[7].
 623
 624A git project normally consists of a working directory with a ".git"
 625subdirectory at the top level.  The .git directory contains, among other
 626things, a compressed object database representing the complete history
 627of the project, an "index" file which links that history to the current
 628contents of the working tree, and named pointers into that history such
 629as tags and branch heads.
 630
 631The object database contains objects of three main types: blobs, which
 632hold file data; trees, which point to blobs and other trees to build up
 633directory hierarchies; and commits, which each reference a single tree
 634and some number of parent commits.
 635
 636The commit, equivalent to what other systems call a "changeset" or
 637"version", represents a step in the project's history, and each parent
 638represents an immediately preceding step.  Commits with more than one
 639parent represent merges of independent lines of development.
 640
 641All objects are named by the SHA1 hash of their contents, normally
 642written as a string of 40 hex digits.  Such names are globally unique.
 643The entire history leading up to a commit can be vouched for by signing
 644just that commit.  A fourth object type, the tag, is provided for this
 645purpose.
 646
 647When first created, objects are stored in individual files, but for
 648efficiency may later be compressed together into "pack files".
 649
 650Named pointers called refs mark interesting points in history.  A ref
 651may contain the SHA1 name of an object or the name of another ref.  Refs
 652with names beginning `ref/head/` contain the SHA1 name of the most
 653recent commit (or "head") of a branch under development.  SHA1 names of
 654tags of interest are stored under `ref/tags/`.  A special ref named
 655`HEAD` contains the name of the currently checked-out branch.
 656
 657The index file is initialized with a list of all paths and, for each
 658path, a blob object and a set of attributes.  The blob object represents
 659the contents of the file as of the head of the current branch.  The
 660attributes (last modified time, size, etc.) are taken from the
 661corresponding file in the working tree.  Subsequent changes to the
 662working tree can be found by comparing these attributes.  The index may
 663be updated with new content, and new commits may be created from the
 664content stored in the index.
 665
 666The index is also capable of storing multiple entries (called "stages")
 667for a given pathname.  These stages are used to hold the various
 668unmerged version of a file when a merge is in progress.
 669
 670Authors
 671-------
 672* git's founding father is Linus Torvalds <torvalds@osdl.org>.
 673* The current git nurse is Junio C Hamano <gitster@pobox.com>.
 674* The git potty was written by Andreas Ericsson <ae@op5.se>.
 675* General upbringing is handled by the git-list <git@vger.kernel.org>.
 676
 677Documentation
 678--------------
 679The documentation for git suite was started by David Greaves
 680<david@dgreaves.com>, and later enhanced greatly by the
 681contributors on the git-list <git@vger.kernel.org>.
 682
 683SEE ALSO
 684--------
 685linkgit:gittutorial[7], linkgit:gittutorial-2[7],
 686link:everyday.html[Everyday Git], linkgit:gitcvs-migration[7],
 687linkgit:gitglossary[7], linkgit:gitcore-tutorial[7],
 688linkgit:gitcli[7], link:user-manual.html[The Git User's Manual],
 689linkgit:gitworkflows[7]
 690
 691GIT
 692---
 693Part of the linkgit:git[1] suite