Documentation / git.txton commit Allow passing of configuration parameters in the command line (8b1fa77)
   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    [-c name=value]
  16    [--help] COMMAND [ARGS]
  17
  18DESCRIPTION
  19-----------
  20Git is a fast, scalable, distributed revision control system with an
  21unusually rich command set that provides both high-level operations
  22and full access to internals.
  23
  24See linkgit:gittutorial[7] to get started, then see
  25link:everyday.html[Everyday Git] for a useful minimum set of commands, and
  26"man git-commandname" for documentation of each command.  CVS users may
  27also want to read linkgit:gitcvs-migration[7].  See
  28the link:user-manual.html[Git User's Manual] for a more in-depth
  29introduction.
  30
  31The COMMAND is either a name of a Git command (see below) or an alias
  32as defined in the configuration file (see linkgit:git-config[1]).
  33
  34Formatted and hyperlinked version of the latest git
  35documentation can be viewed at
  36`http://www.kernel.org/pub/software/scm/git/docs/`.
  37
  38ifdef::stalenotes[]
  39[NOTE]
  40============
  41
  42You are reading the documentation for the latest (possibly
  43unreleased) version of git, that is available from 'master'
  44branch of the `git.git` repository.
  45Documentation for older releases are available here:
  46
  47* link:v1.7.0.2/git.html[documentation for release 1.7.0.2]
  48
  49* release notes for
  50  link:RelNotes-1.7.0.2.txt[1.7.0.2],
  51  link:RelNotes-1.7.0.1.txt[1.7.0.1],
  52  link:RelNotes-1.7.0.txt[1.7.0].
  53
  54* link:v1.6.6.2/git.html[documentation for release 1.6.6.2]
  55
  56* release notes for
  57  link:RelNotes-1.6.6.2.txt[1.6.6.2],
  58  link:RelNotes-1.6.6.1.txt[1.6.6.1],
  59  link:RelNotes-1.6.6.txt[1.6.6].
  60
  61* link:v1.6.5.8/git.html[documentation for release 1.6.5.8]
  62
  63* release notes for
  64  link:RelNotes-1.6.5.8.txt[1.6.5.8],
  65  link:RelNotes-1.6.5.7.txt[1.6.5.7],
  66  link:RelNotes-1.6.5.6.txt[1.6.5.6],
  67  link:RelNotes-1.6.5.5.txt[1.6.5.5],
  68  link:RelNotes-1.6.5.4.txt[1.6.5.4],
  69  link:RelNotes-1.6.5.3.txt[1.6.5.3],
  70  link:RelNotes-1.6.5.2.txt[1.6.5.2],
  71  link:RelNotes-1.6.5.1.txt[1.6.5.1],
  72  link:RelNotes-1.6.5.txt[1.6.5].
  73
  74* link:v1.6.4.4/git.html[documentation for release 1.6.4.4]
  75
  76* release notes for
  77  link:RelNotes-1.6.4.4.txt[1.6.4.4],
  78  link:RelNotes-1.6.4.3.txt[1.6.4.3],
  79  link:RelNotes-1.6.4.2.txt[1.6.4.2],
  80  link:RelNotes-1.6.4.1.txt[1.6.4.1],
  81  link:RelNotes-1.6.4.txt[1.6.4].
  82
  83* link:v1.6.3.4/git.html[documentation for release 1.6.3.4]
  84
  85* release notes for
  86  link:RelNotes-1.6.3.4.txt[1.6.3.4],
  87  link:RelNotes-1.6.3.3.txt[1.6.3.3],
  88  link:RelNotes-1.6.3.2.txt[1.6.3.2],
  89  link:RelNotes-1.6.3.1.txt[1.6.3.1],
  90  link:RelNotes-1.6.3.txt[1.6.3].
  91
  92* release notes for
  93  link:RelNotes-1.6.2.5.txt[1.6.2.5],
  94  link:RelNotes-1.6.2.4.txt[1.6.2.4],
  95  link:RelNotes-1.6.2.3.txt[1.6.2.3],
  96  link:RelNotes-1.6.2.2.txt[1.6.2.2],
  97  link:RelNotes-1.6.2.1.txt[1.6.2.1],
  98  link:RelNotes-1.6.2.txt[1.6.2].
  99
 100* link:v1.6.1.3/git.html[documentation for release 1.6.1.3]
 101
 102* release notes for
 103  link:RelNotes-1.6.1.3.txt[1.6.1.3],
 104  link:RelNotes-1.6.1.2.txt[1.6.1.2],
 105  link:RelNotes-1.6.1.1.txt[1.6.1.1],
 106  link:RelNotes-1.6.1.txt[1.6.1].
 107
 108* link:v1.6.0.6/git.html[documentation for release 1.6.0.6]
 109
 110* release notes for
 111  link:RelNotes-1.6.0.6.txt[1.6.0.6],
 112  link:RelNotes-1.6.0.5.txt[1.6.0.5],
 113  link:RelNotes-1.6.0.4.txt[1.6.0.4],
 114  link:RelNotes-1.6.0.3.txt[1.6.0.3],
 115  link:RelNotes-1.6.0.2.txt[1.6.0.2],
 116  link:RelNotes-1.6.0.1.txt[1.6.0.1],
 117  link:RelNotes-1.6.0.txt[1.6.0].
 118
 119* link:v1.5.6.6/git.html[documentation for release 1.5.6.6]
 120
 121* release notes for
 122  link:RelNotes-1.5.6.6.txt[1.5.6.6],
 123  link:RelNotes-1.5.6.5.txt[1.5.6.5],
 124  link:RelNotes-1.5.6.4.txt[1.5.6.4],
 125  link:RelNotes-1.5.6.3.txt[1.5.6.3],
 126  link:RelNotes-1.5.6.2.txt[1.5.6.2],
 127  link:RelNotes-1.5.6.1.txt[1.5.6.1],
 128  link:RelNotes-1.5.6.txt[1.5.6].
 129
 130* link:v1.5.5.6/git.html[documentation for release 1.5.5.6]
 131
 132* release notes for
 133  link:RelNotes-1.5.5.6.txt[1.5.5.6],
 134  link:RelNotes-1.5.5.5.txt[1.5.5.5],
 135  link:RelNotes-1.5.5.4.txt[1.5.5.4],
 136  link:RelNotes-1.5.5.3.txt[1.5.5.3],
 137  link:RelNotes-1.5.5.2.txt[1.5.5.2],
 138  link:RelNotes-1.5.5.1.txt[1.5.5.1],
 139  link:RelNotes-1.5.5.txt[1.5.5].
 140
 141* link:v1.5.4.7/git.html[documentation for release 1.5.4.7]
 142
 143* release notes for
 144  link:RelNotes-1.5.4.7.txt[1.5.4.7],
 145  link:RelNotes-1.5.4.6.txt[1.5.4.6],
 146  link:RelNotes-1.5.4.5.txt[1.5.4.5],
 147  link:RelNotes-1.5.4.4.txt[1.5.4.4],
 148  link:RelNotes-1.5.4.3.txt[1.5.4.3],
 149  link:RelNotes-1.5.4.2.txt[1.5.4.2],
 150  link:RelNotes-1.5.4.1.txt[1.5.4.1],
 151  link:RelNotes-1.5.4.txt[1.5.4].
 152
 153* link:v1.5.3.8/git.html[documentation for release 1.5.3.8]
 154
 155* release notes for
 156  link:RelNotes-1.5.3.8.txt[1.5.3.8],
 157  link:RelNotes-1.5.3.7.txt[1.5.3.7],
 158  link:RelNotes-1.5.3.6.txt[1.5.3.6],
 159  link:RelNotes-1.5.3.5.txt[1.5.3.5],
 160  link:RelNotes-1.5.3.4.txt[1.5.3.4],
 161  link:RelNotes-1.5.3.3.txt[1.5.3.3],
 162  link:RelNotes-1.5.3.2.txt[1.5.3.2],
 163  link:RelNotes-1.5.3.1.txt[1.5.3.1],
 164  link:RelNotes-1.5.3.txt[1.5.3].
 165
 166* link:v1.5.2.5/git.html[documentation for release 1.5.2.5]
 167
 168* release notes for
 169  link:RelNotes-1.5.2.5.txt[1.5.2.5],
 170  link:RelNotes-1.5.2.4.txt[1.5.2.4],
 171  link:RelNotes-1.5.2.3.txt[1.5.2.3],
 172  link:RelNotes-1.5.2.2.txt[1.5.2.2],
 173  link:RelNotes-1.5.2.1.txt[1.5.2.1],
 174  link:RelNotes-1.5.2.txt[1.5.2].
 175
 176* link:v1.5.1.6/git.html[documentation for release 1.5.1.6]
 177
 178* release notes for
 179  link:RelNotes-1.5.1.6.txt[1.5.1.6],
 180  link:RelNotes-1.5.1.5.txt[1.5.1.5],
 181  link:RelNotes-1.5.1.4.txt[1.5.1.4],
 182  link:RelNotes-1.5.1.3.txt[1.5.1.3],
 183  link:RelNotes-1.5.1.2.txt[1.5.1.2],
 184  link:RelNotes-1.5.1.1.txt[1.5.1.1],
 185  link:RelNotes-1.5.1.txt[1.5.1].
 186
 187* link:v1.5.0.7/git.html[documentation for release 1.5.0.7]
 188
 189* release notes for
 190  link:RelNotes-1.5.0.7.txt[1.5.0.7],
 191  link:RelNotes-1.5.0.6.txt[1.5.0.6],
 192  link:RelNotes-1.5.0.5.txt[1.5.0.5],
 193  link:RelNotes-1.5.0.3.txt[1.5.0.3],
 194  link:RelNotes-1.5.0.2.txt[1.5.0.2],
 195  link:RelNotes-1.5.0.1.txt[1.5.0.1],
 196  link:RelNotes-1.5.0.txt[1.5.0].
 197
 198* documentation for release link:v1.4.4.4/git.html[1.4.4.4],
 199  link:v1.3.3/git.html[1.3.3],
 200  link:v1.2.6/git.html[1.2.6],
 201  link:v1.0.13/git.html[1.0.13].
 202
 203============
 204
 205endif::stalenotes[]
 206
 207OPTIONS
 208-------
 209--version::
 210        Prints the git suite version that the 'git' program came from.
 211
 212--help::
 213        Prints the synopsis and a list of the most commonly used
 214        commands. If the option '--all' or '-a' is given then all
 215        available commands are printed. If a git command is named this
 216        option will bring up the manual page for that command.
 217+
 218Other options are available to control how the manual page is
 219displayed. See linkgit:git-help[1] for more information,
 220because `git --help ...` is converted internally into `git
 221help ...`.
 222
 223-c <name>=<value>::
 224        Pass a configuration parameter to the command. The value
 225        given will override values from configuration files.
 226        The <name> is expected in the same format as listed by
 227        'git config' (subkeys separated by dots).
 228
 229--exec-path::
 230        Path to wherever your core git programs are installed.
 231        This can also be controlled by setting the GIT_EXEC_PATH
 232        environment variable. If no path is given, 'git' will print
 233        the current setting and then exit.
 234
 235--html-path::
 236        Print the path to wherever your git HTML documentation is installed
 237        and exit.
 238
 239-p::
 240--paginate::
 241        Pipe all output into 'less' (or if set, $PAGER) if standard
 242        output is a terminal.  This overrides the `pager.<cmd>`
 243        configuration options (see the "Configuration Mechanism" section
 244        below).
 245
 246--no-pager::
 247        Do not pipe git output into a pager.
 248
 249--git-dir=<path>::
 250        Set the path to the repository. This can also be controlled by
 251        setting the GIT_DIR environment variable. It can be an absolute
 252        path or relative path to current working directory.
 253
 254--work-tree=<path>::
 255        Set the path to the working tree.  The value will not be
 256        used in combination with repositories found automatically in
 257        a .git directory (i.e. $GIT_DIR is not set).
 258        This can also be controlled by setting the GIT_WORK_TREE
 259        environment variable and the core.worktree configuration
 260        variable. It can be an absolute path or relative path to
 261        the directory specified by --git-dir or GIT_DIR.
 262        Note: If --git-dir or GIT_DIR are specified but none of
 263        --work-tree, GIT_WORK_TREE and core.worktree is specified,
 264        the current working directory is regarded as the top directory
 265        of your working tree.
 266
 267--bare::
 268        Treat the repository as a bare repository.  If GIT_DIR
 269        environment is not set, it is set to the current working
 270        directory.
 271
 272--no-replace-objects::
 273        Do not use replacement refs to replace git objects. See
 274        linkgit:git-replace[1] for more information.
 275
 276
 277FURTHER DOCUMENTATION
 278---------------------
 279
 280See the references above to get started using git.  The following is
 281probably more detail than necessary for a first-time user.
 282
 283The link:user-manual.html#git-concepts[git concepts chapter of the
 284user-manual] and linkgit:gitcore-tutorial[7] both provide
 285introductions to the underlying git architecture.
 286
 287See linkgit:gitworkflows[7] for an overview of recommended workflows.
 288
 289See also the link:howto-index.html[howto] documents for some useful
 290examples.
 291
 292The internals are documented in the
 293link:technical/api-index.html[GIT API documentation].
 294
 295GIT COMMANDS
 296------------
 297
 298We divide git into high level ("porcelain") commands and low level
 299("plumbing") commands.
 300
 301High-level commands (porcelain)
 302-------------------------------
 303
 304We separate the porcelain commands into the main commands and some
 305ancillary user utilities.
 306
 307Main porcelain commands
 308~~~~~~~~~~~~~~~~~~~~~~~
 309
 310include::cmds-mainporcelain.txt[]
 311
 312Ancillary Commands
 313~~~~~~~~~~~~~~~~~~
 314Manipulators:
 315
 316include::cmds-ancillarymanipulators.txt[]
 317
 318Interrogators:
 319
 320include::cmds-ancillaryinterrogators.txt[]
 321
 322
 323Interacting with Others
 324~~~~~~~~~~~~~~~~~~~~~~~
 325
 326These commands are to interact with foreign SCM and with other
 327people via patch over e-mail.
 328
 329include::cmds-foreignscminterface.txt[]
 330
 331
 332Low-level commands (plumbing)
 333-----------------------------
 334
 335Although git includes its
 336own porcelain layer, its low-level commands are sufficient to support
 337development of alternative porcelains.  Developers of such porcelains
 338might start by reading about linkgit:git-update-index[1] and
 339linkgit:git-read-tree[1].
 340
 341The interface (input, output, set of options and the semantics)
 342to these low-level commands are meant to be a lot more stable
 343than Porcelain level commands, because these commands are
 344primarily for scripted use.  The interface to Porcelain commands
 345on the other hand are subject to change in order to improve the
 346end user experience.
 347
 348The following description divides
 349the low-level commands into commands that manipulate objects (in
 350the repository, index, and working tree), commands that interrogate and
 351compare objects, and commands that move objects and references between
 352repositories.
 353
 354
 355Manipulation commands
 356~~~~~~~~~~~~~~~~~~~~~
 357
 358include::cmds-plumbingmanipulators.txt[]
 359
 360
 361Interrogation commands
 362~~~~~~~~~~~~~~~~~~~~~~
 363
 364include::cmds-plumbinginterrogators.txt[]
 365
 366In general, the interrogate commands do not touch the files in
 367the working tree.
 368
 369
 370Synching repositories
 371~~~~~~~~~~~~~~~~~~~~~
 372
 373include::cmds-synchingrepositories.txt[]
 374
 375The following are helper commands used by the above; end users
 376typically do not use them directly.
 377
 378include::cmds-synchelpers.txt[]
 379
 380
 381Internal helper commands
 382~~~~~~~~~~~~~~~~~~~~~~~~
 383
 384These are internal helper commands used by other commands; end
 385users typically do not use them directly.
 386
 387include::cmds-purehelpers.txt[]
 388
 389
 390Configuration Mechanism
 391-----------------------
 392
 393Starting from 0.99.9 (actually mid 0.99.8.GIT), `.git/config` file
 394is used to hold per-repository configuration options.  It is a
 395simple text file modeled after `.ini` format familiar to some
 396people.  Here is an example:
 397
 398------------
 399#
 400# A '#' or ';' character indicates a comment.
 401#
 402
 403; core variables
 404[core]
 405        ; Don't trust file modes
 406        filemode = false
 407
 408; user identity
 409[user]
 410        name = "Junio C Hamano"
 411        email = "junkio@twinsun.com"
 412
 413------------
 414
 415Various commands read from the configuration file and adjust
 416their operation accordingly.  See linkgit:git-config[1] for a
 417list.
 418
 419
 420Identifier Terminology
 421----------------------
 422<object>::
 423        Indicates the object name for any type of object.
 424
 425<blob>::
 426        Indicates a blob object name.
 427
 428<tree>::
 429        Indicates a tree object name.
 430
 431<commit>::
 432        Indicates a commit object name.
 433
 434<tree-ish>::
 435        Indicates a tree, commit or tag object name.  A
 436        command that takes a <tree-ish> argument ultimately wants to
 437        operate on a <tree> object but automatically dereferences
 438        <commit> and <tag> objects that point at a <tree>.
 439
 440<commit-ish>::
 441        Indicates a commit or tag object name.  A
 442        command that takes a <commit-ish> argument ultimately wants to
 443        operate on a <commit> object but automatically dereferences
 444        <tag> objects that point at a <commit>.
 445
 446<type>::
 447        Indicates that an object type is required.
 448        Currently one of: `blob`, `tree`, `commit`, or `tag`.
 449
 450<file>::
 451        Indicates a filename - almost always relative to the
 452        root of the tree structure `GIT_INDEX_FILE` describes.
 453
 454Symbolic Identifiers
 455--------------------
 456Any git command accepting any <object> can also use the following
 457symbolic notation:
 458
 459HEAD::
 460        indicates the head of the current branch (i.e. the
 461        contents of `$GIT_DIR/HEAD`).
 462
 463<tag>::
 464        a valid tag 'name'
 465        (i.e. the contents of `$GIT_DIR/refs/tags/<tag>`).
 466
 467<head>::
 468        a valid head 'name'
 469        (i.e. the contents of `$GIT_DIR/refs/heads/<head>`).
 470
 471For a more complete list of ways to spell object names, see
 472"SPECIFYING REVISIONS" section in linkgit:git-rev-parse[1].
 473
 474
 475File/Directory Structure
 476------------------------
 477
 478Please see the linkgit:gitrepository-layout[5] document.
 479
 480Read linkgit:githooks[5] for more details about each hook.
 481
 482Higher level SCMs may provide and manage additional information in the
 483`$GIT_DIR`.
 484
 485
 486Terminology
 487-----------
 488Please see linkgit:gitglossary[7].
 489
 490
 491Environment Variables
 492---------------------
 493Various git commands use the following environment variables:
 494
 495The git Repository
 496~~~~~~~~~~~~~~~~~~
 497These environment variables apply to 'all' core git commands. Nb: it
 498is worth noting that they may be used/overridden by SCMS sitting above
 499git so take care if using Cogito etc.
 500
 501'GIT_INDEX_FILE'::
 502        This environment allows the specification of an alternate
 503        index file. If not specified, the default of `$GIT_DIR/index`
 504        is used.
 505
 506'GIT_OBJECT_DIRECTORY'::
 507        If the object storage directory is specified via this
 508        environment variable then the sha1 directories are created
 509        underneath - otherwise the default `$GIT_DIR/objects`
 510        directory is used.
 511
 512'GIT_ALTERNATE_OBJECT_DIRECTORIES'::
 513        Due to the immutable nature of git objects, old objects can be
 514        archived into shared, read-only directories. This variable
 515        specifies a ":" separated (on Windows ";" separated) list
 516        of git object directories which can be used to search for git
 517        objects. New objects will not be written to these directories.
 518
 519'GIT_DIR'::
 520        If the 'GIT_DIR' environment variable is set then it
 521        specifies a path to use instead of the default `.git`
 522        for the base of the repository.
 523
 524'GIT_WORK_TREE'::
 525        Set the path to the working tree.  The value will not be
 526        used in combination with repositories found automatically in
 527        a .git directory (i.e. $GIT_DIR is not set).
 528        This can also be controlled by the '--work-tree' command line
 529        option and the core.worktree configuration variable.
 530
 531'GIT_CEILING_DIRECTORIES'::
 532        This should be a colon-separated list of absolute paths.
 533        If set, it is a list of directories that git should not chdir
 534        up into while looking for a repository directory.
 535        It will not exclude the current working directory or
 536        a GIT_DIR set on the command line or in the environment.
 537        (Useful for excluding slow-loading network directories.)
 538
 539git Commits
 540~~~~~~~~~~~
 541'GIT_AUTHOR_NAME'::
 542'GIT_AUTHOR_EMAIL'::
 543'GIT_AUTHOR_DATE'::
 544'GIT_COMMITTER_NAME'::
 545'GIT_COMMITTER_EMAIL'::
 546'GIT_COMMITTER_DATE'::
 547'EMAIL'::
 548        see linkgit:git-commit-tree[1]
 549
 550git Diffs
 551~~~~~~~~~
 552'GIT_DIFF_OPTS'::
 553        Only valid setting is "--unified=??" or "-u??" to set the
 554        number of context lines shown when a unified diff is created.
 555        This takes precedence over any "-U" or "--unified" option
 556        value passed on the git diff command line.
 557
 558'GIT_EXTERNAL_DIFF'::
 559        When the environment variable 'GIT_EXTERNAL_DIFF' is set, the
 560        program named by it is called, instead of the diff invocation
 561        described above.  For a path that is added, removed, or modified,
 562        'GIT_EXTERNAL_DIFF' is called with 7 parameters:
 563
 564        path old-file old-hex old-mode new-file new-hex new-mode
 565+
 566where:
 567
 568        <old|new>-file:: are files GIT_EXTERNAL_DIFF can use to read the
 569                         contents of <old|new>,
 570        <old|new>-hex:: are the 40-hexdigit SHA1 hashes,
 571        <old|new>-mode:: are the octal representation of the file modes.
 572
 573+
 574The file parameters can point at the user's working file
 575(e.g. `new-file` in "git-diff-files"), `/dev/null` (e.g. `old-file`
 576when a new file is added), or a temporary file (e.g. `old-file` in the
 577index).  'GIT_EXTERNAL_DIFF' should not worry about unlinking the
 578temporary file --- it is removed when 'GIT_EXTERNAL_DIFF' exits.
 579+
 580For a path that is unmerged, 'GIT_EXTERNAL_DIFF' is called with 1
 581parameter, <path>.
 582
 583other
 584~~~~~
 585'GIT_MERGE_VERBOSITY'::
 586        A number controlling the amount of output shown by
 587        the recursive merge strategy.  Overrides merge.verbosity.
 588        See linkgit:git-merge[1]
 589
 590'GIT_PAGER'::
 591        This environment variable overrides `$PAGER`. If it is set
 592        to an empty string or to the value "cat", git will not launch
 593        a pager.  See also the `core.pager` option in
 594        linkgit:git-config[1].
 595
 596'GIT_SSH'::
 597        If this environment variable is set then 'git fetch'
 598        and 'git push' will use this command instead
 599        of 'ssh' when they need to connect to a remote system.
 600        The '$GIT_SSH' command will be given exactly two arguments:
 601        the 'username@host' (or just 'host') from the URL and the
 602        shell command to execute on that remote system.
 603+
 604To pass options to the program that you want to list in GIT_SSH
 605you will need to wrap the program and options into a shell script,
 606then set GIT_SSH to refer to the shell script.
 607+
 608Usually it is easier to configure any desired options through your
 609personal `.ssh/config` file.  Please consult your ssh documentation
 610for further details.
 611
 612'GIT_FLUSH'::
 613        If this environment variable is set to "1", then commands such
 614        as 'git blame' (in incremental mode), 'git rev-list', 'git log',
 615        and 'git whatchanged' will force a flush of the output stream
 616        after each commit-oriented record have been flushed.   If this
 617        variable is set to "0", the output of these commands will be done
 618        using completely buffered I/O.   If this environment variable is
 619        not set, git will choose buffered or record-oriented flushing
 620        based on whether stdout appears to be redirected to a file or not.
 621
 622'GIT_TRACE'::
 623        If this variable is set to "1", "2" or "true" (comparison
 624        is case insensitive), git will print `trace:` messages on
 625        stderr telling about alias expansion, built-in command
 626        execution and external command execution.
 627        If this variable is set to an integer value greater than 1
 628        and lower than 10 (strictly) then git will interpret this
 629        value as an open file descriptor and will try to write the
 630        trace messages into this file descriptor.
 631        Alternatively, if this variable is set to an absolute path
 632        (starting with a '/' character), git will interpret this
 633        as a file path and will try to write the trace messages
 634        into it.
 635
 636Discussion[[Discussion]]
 637------------------------
 638
 639More detail on the following is available from the
 640link:user-manual.html#git-concepts[git concepts chapter of the
 641user-manual] and linkgit:gitcore-tutorial[7].
 642
 643A git project normally consists of a working directory with a ".git"
 644subdirectory at the top level.  The .git directory contains, among other
 645things, a compressed object database representing the complete history
 646of the project, an "index" file which links that history to the current
 647contents of the working tree, and named pointers into that history such
 648as tags and branch heads.
 649
 650The object database contains objects of three main types: blobs, which
 651hold file data; trees, which point to blobs and other trees to build up
 652directory hierarchies; and commits, which each reference a single tree
 653and some number of parent commits.
 654
 655The commit, equivalent to what other systems call a "changeset" or
 656"version", represents a step in the project's history, and each parent
 657represents an immediately preceding step.  Commits with more than one
 658parent represent merges of independent lines of development.
 659
 660All objects are named by the SHA1 hash of their contents, normally
 661written as a string of 40 hex digits.  Such names are globally unique.
 662The entire history leading up to a commit can be vouched for by signing
 663just that commit.  A fourth object type, the tag, is provided for this
 664purpose.
 665
 666When first created, objects are stored in individual files, but for
 667efficiency may later be compressed together into "pack files".
 668
 669Named pointers called refs mark interesting points in history.  A ref
 670may contain the SHA1 name of an object or the name of another ref.  Refs
 671with names beginning `ref/head/` contain the SHA1 name of the most
 672recent commit (or "head") of a branch under development.  SHA1 names of
 673tags of interest are stored under `ref/tags/`.  A special ref named
 674`HEAD` contains the name of the currently checked-out branch.
 675
 676The index file is initialized with a list of all paths and, for each
 677path, a blob object and a set of attributes.  The blob object represents
 678the contents of the file as of the head of the current branch.  The
 679attributes (last modified time, size, etc.) are taken from the
 680corresponding file in the working tree.  Subsequent changes to the
 681working tree can be found by comparing these attributes.  The index may
 682be updated with new content, and new commits may be created from the
 683content stored in the index.
 684
 685The index is also capable of storing multiple entries (called "stages")
 686for a given pathname.  These stages are used to hold the various
 687unmerged version of a file when a merge is in progress.
 688
 689Authors
 690-------
 691* git's founding father is Linus Torvalds <torvalds@osdl.org>.
 692* The current git nurse is Junio C Hamano <gitster@pobox.com>.
 693* The git potty was written by Andreas Ericsson <ae@op5.se>.
 694* General upbringing is handled by the git-list <git@vger.kernel.org>.
 695
 696Documentation
 697--------------
 698The documentation for git suite was started by David Greaves
 699<david@dgreaves.com>, and later enhanced greatly by the
 700contributors on the git-list <git@vger.kernel.org>.
 701
 702SEE ALSO
 703--------
 704linkgit:gittutorial[7], linkgit:gittutorial-2[7],
 705link:everyday.html[Everyday Git], linkgit:gitcvs-migration[7],
 706linkgit:gitglossary[7], linkgit:gitcore-tutorial[7],
 707linkgit:gitcli[7], link:user-manual.html[The Git User's Manual],
 708linkgit:gitworkflows[7]
 709
 710GIT
 711---
 712Part of the linkgit:git[1] suite