abbd9848e44b69904e0446dba46b694d118c366e
   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
  47* link:v1.7.1/git.html[documentation for release 1.7.1]
  48
  49* release notes for
  50  link:RelNotes-1.7.1.txt[1.7.1].
  51
  52* link:v1.7.0.7/git.html[documentation for release 1.7.0.7]
  53
  54* release notes for
  55  link:RelNotes-1.7.0.7.txt[1.7.0.7],
  56  link:RelNotes-1.7.0.6.txt[1.7.0.6],
  57  link:RelNotes-1.7.0.5.txt[1.7.0.5],
  58  link:RelNotes-1.7.0.4.txt[1.7.0.4],
  59  link:RelNotes-1.7.0.3.txt[1.7.0.3],
  60  link:RelNotes-1.7.0.2.txt[1.7.0.2],
  61  link:RelNotes-1.7.0.1.txt[1.7.0.1],
  62  link:RelNotes-1.7.0.txt[1.7.0].
  63
  64* link:v1.6.6.2/git.html[documentation for release 1.6.6.2]
  65
  66* release notes for
  67  link:RelNotes-1.6.6.2.txt[1.6.6.2],
  68  link:RelNotes-1.6.6.1.txt[1.6.6.1],
  69  link:RelNotes-1.6.6.txt[1.6.6].
  70
  71* link:v1.6.5.8/git.html[documentation for release 1.6.5.8]
  72
  73* release notes for
  74  link:RelNotes-1.6.5.8.txt[1.6.5.8],
  75  link:RelNotes-1.6.5.7.txt[1.6.5.7],
  76  link:RelNotes-1.6.5.6.txt[1.6.5.6],
  77  link:RelNotes-1.6.5.5.txt[1.6.5.5],
  78  link:RelNotes-1.6.5.4.txt[1.6.5.4],
  79  link:RelNotes-1.6.5.3.txt[1.6.5.3],
  80  link:RelNotes-1.6.5.2.txt[1.6.5.2],
  81  link:RelNotes-1.6.5.1.txt[1.6.5.1],
  82  link:RelNotes-1.6.5.txt[1.6.5].
  83
  84* link:v1.6.4.4/git.html[documentation for release 1.6.4.4]
  85
  86* release notes for
  87  link:RelNotes-1.6.4.4.txt[1.6.4.4],
  88  link:RelNotes-1.6.4.3.txt[1.6.4.3],
  89  link:RelNotes-1.6.4.2.txt[1.6.4.2],
  90  link:RelNotes-1.6.4.1.txt[1.6.4.1],
  91  link:RelNotes-1.6.4.txt[1.6.4].
  92
  93* link:v1.6.3.4/git.html[documentation for release 1.6.3.4]
  94
  95* release notes for
  96  link:RelNotes-1.6.3.4.txt[1.6.3.4],
  97  link:RelNotes-1.6.3.3.txt[1.6.3.3],
  98  link:RelNotes-1.6.3.2.txt[1.6.3.2],
  99  link:RelNotes-1.6.3.1.txt[1.6.3.1],
 100  link:RelNotes-1.6.3.txt[1.6.3].
 101
 102* release notes for
 103  link:RelNotes-1.6.2.5.txt[1.6.2.5],
 104  link:RelNotes-1.6.2.4.txt[1.6.2.4],
 105  link:RelNotes-1.6.2.3.txt[1.6.2.3],
 106  link:RelNotes-1.6.2.2.txt[1.6.2.2],
 107  link:RelNotes-1.6.2.1.txt[1.6.2.1],
 108  link:RelNotes-1.6.2.txt[1.6.2].
 109
 110* link:v1.6.1.3/git.html[documentation for release 1.6.1.3]
 111
 112* release notes for
 113  link:RelNotes-1.6.1.3.txt[1.6.1.3],
 114  link:RelNotes-1.6.1.2.txt[1.6.1.2],
 115  link:RelNotes-1.6.1.1.txt[1.6.1.1],
 116  link:RelNotes-1.6.1.txt[1.6.1].
 117
 118* link:v1.6.0.6/git.html[documentation for release 1.6.0.6]
 119
 120* release notes for
 121  link:RelNotes-1.6.0.6.txt[1.6.0.6],
 122  link:RelNotes-1.6.0.5.txt[1.6.0.5],
 123  link:RelNotes-1.6.0.4.txt[1.6.0.4],
 124  link:RelNotes-1.6.0.3.txt[1.6.0.3],
 125  link:RelNotes-1.6.0.2.txt[1.6.0.2],
 126  link:RelNotes-1.6.0.1.txt[1.6.0.1],
 127  link:RelNotes-1.6.0.txt[1.6.0].
 128
 129* link:v1.5.6.6/git.html[documentation for release 1.5.6.6]
 130
 131* release notes for
 132  link:RelNotes-1.5.6.6.txt[1.5.6.6],
 133  link:RelNotes-1.5.6.5.txt[1.5.6.5],
 134  link:RelNotes-1.5.6.4.txt[1.5.6.4],
 135  link:RelNotes-1.5.6.3.txt[1.5.6.3],
 136  link:RelNotes-1.5.6.2.txt[1.5.6.2],
 137  link:RelNotes-1.5.6.1.txt[1.5.6.1],
 138  link:RelNotes-1.5.6.txt[1.5.6].
 139
 140* link:v1.5.5.6/git.html[documentation for release 1.5.5.6]
 141
 142* release notes for
 143  link:RelNotes-1.5.5.6.txt[1.5.5.6],
 144  link:RelNotes-1.5.5.5.txt[1.5.5.5],
 145  link:RelNotes-1.5.5.4.txt[1.5.5.4],
 146  link:RelNotes-1.5.5.3.txt[1.5.5.3],
 147  link:RelNotes-1.5.5.2.txt[1.5.5.2],
 148  link:RelNotes-1.5.5.1.txt[1.5.5.1],
 149  link:RelNotes-1.5.5.txt[1.5.5].
 150
 151* link:v1.5.4.7/git.html[documentation for release 1.5.4.7]
 152
 153* release notes for
 154  link:RelNotes-1.5.4.7.txt[1.5.4.7],
 155  link:RelNotes-1.5.4.6.txt[1.5.4.6],
 156  link:RelNotes-1.5.4.5.txt[1.5.4.5],
 157  link:RelNotes-1.5.4.4.txt[1.5.4.4],
 158  link:RelNotes-1.5.4.3.txt[1.5.4.3],
 159  link:RelNotes-1.5.4.2.txt[1.5.4.2],
 160  link:RelNotes-1.5.4.1.txt[1.5.4.1],
 161  link:RelNotes-1.5.4.txt[1.5.4].
 162
 163* link:v1.5.3.8/git.html[documentation for release 1.5.3.8]
 164
 165* release notes for
 166  link:RelNotes-1.5.3.8.txt[1.5.3.8],
 167  link:RelNotes-1.5.3.7.txt[1.5.3.7],
 168  link:RelNotes-1.5.3.6.txt[1.5.3.6],
 169  link:RelNotes-1.5.3.5.txt[1.5.3.5],
 170  link:RelNotes-1.5.3.4.txt[1.5.3.4],
 171  link:RelNotes-1.5.3.3.txt[1.5.3.3],
 172  link:RelNotes-1.5.3.2.txt[1.5.3.2],
 173  link:RelNotes-1.5.3.1.txt[1.5.3.1],
 174  link:RelNotes-1.5.3.txt[1.5.3].
 175
 176* link:v1.5.2.5/git.html[documentation for release 1.5.2.5]
 177
 178* release notes for
 179  link:RelNotes-1.5.2.5.txt[1.5.2.5],
 180  link:RelNotes-1.5.2.4.txt[1.5.2.4],
 181  link:RelNotes-1.5.2.3.txt[1.5.2.3],
 182  link:RelNotes-1.5.2.2.txt[1.5.2.2],
 183  link:RelNotes-1.5.2.1.txt[1.5.2.1],
 184  link:RelNotes-1.5.2.txt[1.5.2].
 185
 186* link:v1.5.1.6/git.html[documentation for release 1.5.1.6]
 187
 188* release notes for
 189  link:RelNotes-1.5.1.6.txt[1.5.1.6],
 190  link:RelNotes-1.5.1.5.txt[1.5.1.5],
 191  link:RelNotes-1.5.1.4.txt[1.5.1.4],
 192  link:RelNotes-1.5.1.3.txt[1.5.1.3],
 193  link:RelNotes-1.5.1.2.txt[1.5.1.2],
 194  link:RelNotes-1.5.1.1.txt[1.5.1.1],
 195  link:RelNotes-1.5.1.txt[1.5.1].
 196
 197* link:v1.5.0.7/git.html[documentation for release 1.5.0.7]
 198
 199* release notes for
 200  link:RelNotes-1.5.0.7.txt[1.5.0.7],
 201  link:RelNotes-1.5.0.6.txt[1.5.0.6],
 202  link:RelNotes-1.5.0.5.txt[1.5.0.5],
 203  link:RelNotes-1.5.0.3.txt[1.5.0.3],
 204  link:RelNotes-1.5.0.2.txt[1.5.0.2],
 205  link:RelNotes-1.5.0.1.txt[1.5.0.1],
 206  link:RelNotes-1.5.0.txt[1.5.0].
 207
 208* documentation for release link:v1.4.4.4/git.html[1.4.4.4],
 209  link:v1.3.3/git.html[1.3.3],
 210  link:v1.2.6/git.html[1.2.6],
 211  link:v1.0.13/git.html[1.0.13].
 212
 213============
 214
 215endif::stalenotes[]
 216
 217OPTIONS
 218-------
 219--version::
 220        Prints the git suite version that the 'git' program came from.
 221
 222--help::
 223        Prints the synopsis and a list of the most commonly used
 224        commands. If the option '--all' or '-a' is given then all
 225        available commands are printed. If a git command is named this
 226        option will bring up the manual page for that command.
 227+
 228Other options are available to control how the manual page is
 229displayed. See linkgit:git-help[1] for more information,
 230because `git --help ...` is converted internally into `git
 231help ...`.
 232
 233--exec-path::
 234        Path to wherever your core git programs are installed.
 235        This can also be controlled by setting the GIT_EXEC_PATH
 236        environment variable. If no path is given, 'git' will print
 237        the current setting and then exit.
 238
 239--html-path::
 240        Print the path to wherever your git HTML documentation is installed
 241        and exit.
 242
 243-p::
 244--paginate::
 245        Pipe all output into 'less' (or if set, $PAGER) if standard
 246        output is a terminal.  This overrides the `pager.<cmd>`
 247        configuration options (see the "Configuration Mechanism" section
 248        below).
 249
 250--no-pager::
 251        Do not pipe git output into a pager.
 252
 253--git-dir=<path>::
 254        Set the path to the repository. This can also be controlled by
 255        setting the GIT_DIR environment variable. It can be an absolute
 256        path or relative path to current working directory.
 257
 258--work-tree=<path>::
 259        Set the path to the working tree.  The value will not be
 260        used in combination with repositories found automatically in
 261        a .git directory (i.e. $GIT_DIR is not set).
 262        This can also be controlled by setting the GIT_WORK_TREE
 263        environment variable and the core.worktree configuration
 264        variable. It can be an absolute path or relative path to
 265        the directory specified by --git-dir or GIT_DIR.
 266        Note: If --git-dir or GIT_DIR are specified but none of
 267        --work-tree, GIT_WORK_TREE and core.worktree is specified,
 268        the current working directory is regarded as the top directory
 269        of your working tree.
 270
 271--bare::
 272        Treat the repository as a bare repository.  If GIT_DIR
 273        environment is not set, it is set to the current working
 274        directory.
 275
 276--no-replace-objects::
 277        Do not use replacement refs to replace git objects. See
 278        linkgit:git-replace[1] for more information.
 279
 280
 281FURTHER DOCUMENTATION
 282---------------------
 283
 284See the references above to get started using git.  The following is
 285probably more detail than necessary for a first-time user.
 286
 287The link:user-manual.html#git-concepts[git concepts chapter of the
 288user-manual] and linkgit:gitcore-tutorial[7] both provide
 289introductions to the underlying git architecture.
 290
 291See linkgit:gitworkflows[7] for an overview of recommended workflows.
 292
 293See also the link:howto-index.html[howto] documents for some useful
 294examples.
 295
 296The internals are documented in the
 297link:technical/api-index.html[GIT API documentation].
 298
 299GIT COMMANDS
 300------------
 301
 302We divide git into high level ("porcelain") commands and low level
 303("plumbing") commands.
 304
 305High-level commands (porcelain)
 306-------------------------------
 307
 308We separate the porcelain commands into the main commands and some
 309ancillary user utilities.
 310
 311Main porcelain commands
 312~~~~~~~~~~~~~~~~~~~~~~~
 313
 314include::cmds-mainporcelain.txt[]
 315
 316Ancillary Commands
 317~~~~~~~~~~~~~~~~~~
 318Manipulators:
 319
 320include::cmds-ancillarymanipulators.txt[]
 321
 322Interrogators:
 323
 324include::cmds-ancillaryinterrogators.txt[]
 325
 326
 327Interacting with Others
 328~~~~~~~~~~~~~~~~~~~~~~~
 329
 330These commands are to interact with foreign SCM and with other
 331people via patch over e-mail.
 332
 333include::cmds-foreignscminterface.txt[]
 334
 335
 336Low-level commands (plumbing)
 337-----------------------------
 338
 339Although git includes its
 340own porcelain layer, its low-level commands are sufficient to support
 341development of alternative porcelains.  Developers of such porcelains
 342might start by reading about linkgit:git-update-index[1] and
 343linkgit:git-read-tree[1].
 344
 345The interface (input, output, set of options and the semantics)
 346to these low-level commands are meant to be a lot more stable
 347than Porcelain level commands, because these commands are
 348primarily for scripted use.  The interface to Porcelain commands
 349on the other hand are subject to change in order to improve the
 350end user experience.
 351
 352The following description divides
 353the low-level commands into commands that manipulate objects (in
 354the repository, index, and working tree), commands that interrogate and
 355compare objects, and commands that move objects and references between
 356repositories.
 357
 358
 359Manipulation commands
 360~~~~~~~~~~~~~~~~~~~~~
 361
 362include::cmds-plumbingmanipulators.txt[]
 363
 364
 365Interrogation commands
 366~~~~~~~~~~~~~~~~~~~~~~
 367
 368include::cmds-plumbinginterrogators.txt[]
 369
 370In general, the interrogate commands do not touch the files in
 371the working tree.
 372
 373
 374Synching repositories
 375~~~~~~~~~~~~~~~~~~~~~
 376
 377include::cmds-synchingrepositories.txt[]
 378
 379The following are helper commands used by the above; end users
 380typically do not use them directly.
 381
 382include::cmds-synchelpers.txt[]
 383
 384
 385Internal helper commands
 386~~~~~~~~~~~~~~~~~~~~~~~~
 387
 388These are internal helper commands used by other commands; end
 389users typically do not use them directly.
 390
 391include::cmds-purehelpers.txt[]
 392
 393
 394Configuration Mechanism
 395-----------------------
 396
 397Starting from 0.99.9 (actually mid 0.99.8.GIT), `.git/config` file
 398is used to hold per-repository configuration options.  It is a
 399simple text file modeled after `.ini` format familiar to some
 400people.  Here is an example:
 401
 402------------
 403#
 404# A '#' or ';' character indicates a comment.
 405#
 406
 407; core variables
 408[core]
 409        ; Don't trust file modes
 410        filemode = false
 411
 412; user identity
 413[user]
 414        name = "Junio C Hamano"
 415        email = "junkio@twinsun.com"
 416
 417------------
 418
 419Various commands read from the configuration file and adjust
 420their operation accordingly.  See linkgit:git-config[1] for a
 421list.
 422
 423
 424Identifier Terminology
 425----------------------
 426<object>::
 427        Indicates the object name for any type of object.
 428
 429<blob>::
 430        Indicates a blob object name.
 431
 432<tree>::
 433        Indicates a tree object name.
 434
 435<commit>::
 436        Indicates a commit object name.
 437
 438<tree-ish>::
 439        Indicates a tree, commit or tag object name.  A
 440        command that takes a <tree-ish> argument ultimately wants to
 441        operate on a <tree> object but automatically dereferences
 442        <commit> and <tag> objects that point at a <tree>.
 443
 444<commit-ish>::
 445        Indicates a commit or tag object name.  A
 446        command that takes a <commit-ish> argument ultimately wants to
 447        operate on a <commit> object but automatically dereferences
 448        <tag> objects that point at a <commit>.
 449
 450<type>::
 451        Indicates that an object type is required.
 452        Currently one of: `blob`, `tree`, `commit`, or `tag`.
 453
 454<file>::
 455        Indicates a filename - almost always relative to the
 456        root of the tree structure `GIT_INDEX_FILE` describes.
 457
 458Symbolic Identifiers
 459--------------------
 460Any git command accepting any <object> can also use the following
 461symbolic notation:
 462
 463HEAD::
 464        indicates the head of the current branch (i.e. the
 465        contents of `$GIT_DIR/HEAD`).
 466
 467<tag>::
 468        a valid tag 'name'
 469        (i.e. the contents of `$GIT_DIR/refs/tags/<tag>`).
 470
 471<head>::
 472        a valid head 'name'
 473        (i.e. the contents of `$GIT_DIR/refs/heads/<head>`).
 474
 475For a more complete list of ways to spell object names, see
 476"SPECIFYING REVISIONS" section in linkgit:git-rev-parse[1].
 477
 478
 479File/Directory Structure
 480------------------------
 481
 482Please see the linkgit:gitrepository-layout[5] document.
 483
 484Read linkgit:githooks[5] for more details about each hook.
 485
 486Higher level SCMs may provide and manage additional information in the
 487`$GIT_DIR`.
 488
 489
 490Terminology
 491-----------
 492Please see linkgit:gitglossary[7].
 493
 494
 495Environment Variables
 496---------------------
 497Various git commands use the following environment variables:
 498
 499The git Repository
 500~~~~~~~~~~~~~~~~~~
 501These environment variables apply to 'all' core git commands. Nb: it
 502is worth noting that they may be used/overridden by SCMS sitting above
 503git so take care if using Cogito etc.
 504
 505'GIT_INDEX_FILE'::
 506        This environment allows the specification of an alternate
 507        index file. If not specified, the default of `$GIT_DIR/index`
 508        is used.
 509
 510'GIT_OBJECT_DIRECTORY'::
 511        If the object storage directory is specified via this
 512        environment variable then the sha1 directories are created
 513        underneath - otherwise the default `$GIT_DIR/objects`
 514        directory is used.
 515
 516'GIT_ALTERNATE_OBJECT_DIRECTORIES'::
 517        Due to the immutable nature of git objects, old objects can be
 518        archived into shared, read-only directories. This variable
 519        specifies a ":" separated (on Windows ";" separated) list
 520        of git object directories which can be used to search for git
 521        objects. New objects will not be written to these directories.
 522
 523'GIT_DIR'::
 524        If the 'GIT_DIR' environment variable is set then it
 525        specifies a path to use instead of the default `.git`
 526        for the base of the repository.
 527
 528'GIT_WORK_TREE'::
 529        Set the path to the working tree.  The value will not be
 530        used in combination with repositories found automatically in
 531        a .git directory (i.e. $GIT_DIR is not set).
 532        This can also be controlled by the '--work-tree' command line
 533        option and the core.worktree configuration variable.
 534
 535'GIT_CEILING_DIRECTORIES'::
 536        This should be a colon-separated list of absolute paths.
 537        If set, it is a list of directories that git should not chdir
 538        up into while looking for a repository directory.
 539        It will not exclude the current working directory or
 540        a GIT_DIR set on the command line or in the environment.
 541        (Useful for excluding slow-loading network directories.)
 542
 543git Commits
 544~~~~~~~~~~~
 545'GIT_AUTHOR_NAME'::
 546'GIT_AUTHOR_EMAIL'::
 547'GIT_AUTHOR_DATE'::
 548'GIT_COMMITTER_NAME'::
 549'GIT_COMMITTER_EMAIL'::
 550'GIT_COMMITTER_DATE'::
 551'EMAIL'::
 552        see linkgit:git-commit-tree[1]
 553
 554git Diffs
 555~~~~~~~~~
 556'GIT_DIFF_OPTS'::
 557        Only valid setting is "--unified=??" or "-u??" to set the
 558        number of context lines shown when a unified diff is created.
 559        This takes precedence over any "-U" or "--unified" option
 560        value passed on the git diff command line.
 561
 562'GIT_EXTERNAL_DIFF'::
 563        When the environment variable 'GIT_EXTERNAL_DIFF' is set, the
 564        program named by it is called, instead of the diff invocation
 565        described above.  For a path that is added, removed, or modified,
 566        'GIT_EXTERNAL_DIFF' is called with 7 parameters:
 567
 568        path old-file old-hex old-mode new-file new-hex new-mode
 569+
 570where:
 571
 572        <old|new>-file:: are files GIT_EXTERNAL_DIFF can use to read the
 573                         contents of <old|new>,
 574        <old|new>-hex:: are the 40-hexdigit SHA1 hashes,
 575        <old|new>-mode:: are the octal representation of the file modes.
 576
 577+
 578The file parameters can point at the user's working file
 579(e.g. `new-file` in "git-diff-files"), `/dev/null` (e.g. `old-file`
 580when a new file is added), or a temporary file (e.g. `old-file` in the
 581index).  'GIT_EXTERNAL_DIFF' should not worry about unlinking the
 582temporary file --- it is removed when 'GIT_EXTERNAL_DIFF' exits.
 583+
 584For a path that is unmerged, 'GIT_EXTERNAL_DIFF' is called with 1
 585parameter, <path>.
 586
 587other
 588~~~~~
 589'GIT_MERGE_VERBOSITY'::
 590        A number controlling the amount of output shown by
 591        the recursive merge strategy.  Overrides merge.verbosity.
 592        See linkgit:git-merge[1]
 593
 594'GIT_PAGER'::
 595        This environment variable overrides `$PAGER`. If it is set
 596        to an empty string or to the value "cat", git will not launch
 597        a pager.  See also the `core.pager` option in
 598        linkgit:git-config[1].
 599
 600'GIT_SSH'::
 601        If this environment variable is set then 'git fetch'
 602        and 'git push' will use this command instead
 603        of 'ssh' when they need to connect to a remote system.
 604        The '$GIT_SSH' command will be given exactly two arguments:
 605        the 'username@host' (or just 'host') from the URL and the
 606        shell command to execute on that remote system.
 607+
 608To pass options to the program that you want to list in GIT_SSH
 609you will need to wrap the program and options into a shell script,
 610then set GIT_SSH to refer to the shell script.
 611+
 612Usually it is easier to configure any desired options through your
 613personal `.ssh/config` file.  Please consult your ssh documentation
 614for further details.
 615
 616'GIT_FLUSH'::
 617        If this environment variable is set to "1", then commands such
 618        as 'git blame' (in incremental mode), 'git rev-list', 'git log',
 619        and 'git whatchanged' will force a flush of the output stream
 620        after each commit-oriented record have been flushed.   If this
 621        variable is set to "0", the output of these commands will be done
 622        using completely buffered I/O.   If this environment variable is
 623        not set, git will choose buffered or record-oriented flushing
 624        based on whether stdout appears to be redirected to a file or not.
 625
 626'GIT_TRACE'::
 627        If this variable is set to "1", "2" or "true" (comparison
 628        is case insensitive), git will print `trace:` messages on
 629        stderr telling about alias expansion, built-in command
 630        execution and external command execution.
 631        If this variable is set to an integer value greater than 1
 632        and lower than 10 (strictly) then git will interpret this
 633        value as an open file descriptor and will try to write the
 634        trace messages into this file descriptor.
 635        Alternatively, if this variable is set to an absolute path
 636        (starting with a '/' character), git will interpret this
 637        as a file path and will try to write the trace messages
 638        into it.
 639
 640Discussion[[Discussion]]
 641------------------------
 642
 643More detail on the following is available from the
 644link:user-manual.html#git-concepts[git concepts chapter of the
 645user-manual] and linkgit:gitcore-tutorial[7].
 646
 647A git project normally consists of a working directory with a ".git"
 648subdirectory at the top level.  The .git directory contains, among other
 649things, a compressed object database representing the complete history
 650of the project, an "index" file which links that history to the current
 651contents of the working tree, and named pointers into that history such
 652as tags and branch heads.
 653
 654The object database contains objects of three main types: blobs, which
 655hold file data; trees, which point to blobs and other trees to build up
 656directory hierarchies; and commits, which each reference a single tree
 657and some number of parent commits.
 658
 659The commit, equivalent to what other systems call a "changeset" or
 660"version", represents a step in the project's history, and each parent
 661represents an immediately preceding step.  Commits with more than one
 662parent represent merges of independent lines of development.
 663
 664All objects are named by the SHA1 hash of their contents, normally
 665written as a string of 40 hex digits.  Such names are globally unique.
 666The entire history leading up to a commit can be vouched for by signing
 667just that commit.  A fourth object type, the tag, is provided for this
 668purpose.
 669
 670When first created, objects are stored in individual files, but for
 671efficiency may later be compressed together into "pack files".
 672
 673Named pointers called refs mark interesting points in history.  A ref
 674may contain the SHA1 name of an object or the name of another ref.  Refs
 675with names beginning `ref/head/` contain the SHA1 name of the most
 676recent commit (or "head") of a branch under development.  SHA1 names of
 677tags of interest are stored under `ref/tags/`.  A special ref named
 678`HEAD` contains the name of the currently checked-out branch.
 679
 680The index file is initialized with a list of all paths and, for each
 681path, a blob object and a set of attributes.  The blob object represents
 682the contents of the file as of the head of the current branch.  The
 683attributes (last modified time, size, etc.) are taken from the
 684corresponding file in the working tree.  Subsequent changes to the
 685working tree can be found by comparing these attributes.  The index may
 686be updated with new content, and new commits may be created from the
 687content stored in the index.
 688
 689The index is also capable of storing multiple entries (called "stages")
 690for a given pathname.  These stages are used to hold the various
 691unmerged version of a file when a merge is in progress.
 692
 693Authors
 694-------
 695* git's founding father is Linus Torvalds <torvalds@osdl.org>.
 696* The current git nurse is Junio C Hamano <gitster@pobox.com>.
 697* The git potty was written by Andreas Ericsson <ae@op5.se>.
 698* General upbringing is handled by the git-list <git@vger.kernel.org>.
 699
 700Documentation
 701--------------
 702The documentation for git suite was started by David Greaves
 703<david@dgreaves.com>, and later enhanced greatly by the
 704contributors on the git-list <git@vger.kernel.org>.
 705
 706SEE ALSO
 707--------
 708linkgit:gittutorial[7], linkgit:gittutorial-2[7],
 709link:everyday.html[Everyday Git], linkgit:gitcvs-migration[7],
 710linkgit:gitglossary[7], linkgit:gitcore-tutorial[7],
 711linkgit:gitcli[7], link:user-manual.html[The Git User's Manual],
 712linkgit:gitworkflows[7]
 713
 714GIT
 715---
 716Part of the linkgit:git[1] suite