Documentation / git.txton commit fast-import: introduce "feature notes" command (547e8b9)
   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:v1.7.0.7/git.html[documentation for release 1.7.0.7]
  47
  48* release notes for
  49  link:RelNotes-1.7.0.7.txt[1.7.0.7],
  50  link:RelNotes-1.7.0.6.txt[1.7.0.6],
  51  link:RelNotes-1.7.0.5.txt[1.7.0.5],
  52  link:RelNotes-1.7.0.4.txt[1.7.0.4],
  53  link:RelNotes-1.7.0.3.txt[1.7.0.3],
  54  link:RelNotes-1.7.0.2.txt[1.7.0.2],
  55  link:RelNotes-1.7.0.1.txt[1.7.0.1],
  56  link:RelNotes-1.7.0.txt[1.7.0].
  57
  58* link:v1.6.6.2/git.html[documentation for release 1.6.6.2]
  59
  60* release notes for
  61  link:RelNotes-1.6.6.2.txt[1.6.6.2],
  62  link:RelNotes-1.6.6.1.txt[1.6.6.1],
  63  link:RelNotes-1.6.6.txt[1.6.6].
  64
  65* link:v1.6.5.8/git.html[documentation for release 1.6.5.8]
  66
  67* release notes for
  68  link:RelNotes-1.6.5.8.txt[1.6.5.8],
  69  link:RelNotes-1.6.5.7.txt[1.6.5.7],
  70  link:RelNotes-1.6.5.6.txt[1.6.5.6],
  71  link:RelNotes-1.6.5.5.txt[1.6.5.5],
  72  link:RelNotes-1.6.5.4.txt[1.6.5.4],
  73  link:RelNotes-1.6.5.3.txt[1.6.5.3],
  74  link:RelNotes-1.6.5.2.txt[1.6.5.2],
  75  link:RelNotes-1.6.5.1.txt[1.6.5.1],
  76  link:RelNotes-1.6.5.txt[1.6.5].
  77
  78* link:v1.6.4.4/git.html[documentation for release 1.6.4.4]
  79
  80* release notes for
  81  link:RelNotes-1.6.4.4.txt[1.6.4.4],
  82  link:RelNotes-1.6.4.3.txt[1.6.4.3],
  83  link:RelNotes-1.6.4.2.txt[1.6.4.2],
  84  link:RelNotes-1.6.4.1.txt[1.6.4.1],
  85  link:RelNotes-1.6.4.txt[1.6.4].
  86
  87* link:v1.6.3.4/git.html[documentation for release 1.6.3.4]
  88
  89* release notes for
  90  link:RelNotes-1.6.3.4.txt[1.6.3.4],
  91  link:RelNotes-1.6.3.3.txt[1.6.3.3],
  92  link:RelNotes-1.6.3.2.txt[1.6.3.2],
  93  link:RelNotes-1.6.3.1.txt[1.6.3.1],
  94  link:RelNotes-1.6.3.txt[1.6.3].
  95
  96* release notes for
  97  link:RelNotes-1.6.2.5.txt[1.6.2.5],
  98  link:RelNotes-1.6.2.4.txt[1.6.2.4],
  99  link:RelNotes-1.6.2.3.txt[1.6.2.3],
 100  link:RelNotes-1.6.2.2.txt[1.6.2.2],
 101  link:RelNotes-1.6.2.1.txt[1.6.2.1],
 102  link:RelNotes-1.6.2.txt[1.6.2].
 103
 104* link:v1.6.1.3/git.html[documentation for release 1.6.1.3]
 105
 106* release notes for
 107  link:RelNotes-1.6.1.3.txt[1.6.1.3],
 108  link:RelNotes-1.6.1.2.txt[1.6.1.2],
 109  link:RelNotes-1.6.1.1.txt[1.6.1.1],
 110  link:RelNotes-1.6.1.txt[1.6.1].
 111
 112* link:v1.6.0.6/git.html[documentation for release 1.6.0.6]
 113
 114* release notes for
 115  link:RelNotes-1.6.0.6.txt[1.6.0.6],
 116  link:RelNotes-1.6.0.5.txt[1.6.0.5],
 117  link:RelNotes-1.6.0.4.txt[1.6.0.4],
 118  link:RelNotes-1.6.0.3.txt[1.6.0.3],
 119  link:RelNotes-1.6.0.2.txt[1.6.0.2],
 120  link:RelNotes-1.6.0.1.txt[1.6.0.1],
 121  link:RelNotes-1.6.0.txt[1.6.0].
 122
 123* link:v1.5.6.6/git.html[documentation for release 1.5.6.6]
 124
 125* release notes for
 126  link:RelNotes-1.5.6.6.txt[1.5.6.6],
 127  link:RelNotes-1.5.6.5.txt[1.5.6.5],
 128  link:RelNotes-1.5.6.4.txt[1.5.6.4],
 129  link:RelNotes-1.5.6.3.txt[1.5.6.3],
 130  link:RelNotes-1.5.6.2.txt[1.5.6.2],
 131  link:RelNotes-1.5.6.1.txt[1.5.6.1],
 132  link:RelNotes-1.5.6.txt[1.5.6].
 133
 134* link:v1.5.5.6/git.html[documentation for release 1.5.5.6]
 135
 136* release notes for
 137  link:RelNotes-1.5.5.6.txt[1.5.5.6],
 138  link:RelNotes-1.5.5.5.txt[1.5.5.5],
 139  link:RelNotes-1.5.5.4.txt[1.5.5.4],
 140  link:RelNotes-1.5.5.3.txt[1.5.5.3],
 141  link:RelNotes-1.5.5.2.txt[1.5.5.2],
 142  link:RelNotes-1.5.5.1.txt[1.5.5.1],
 143  link:RelNotes-1.5.5.txt[1.5.5].
 144
 145* link:v1.5.4.7/git.html[documentation for release 1.5.4.7]
 146
 147* release notes for
 148  link:RelNotes-1.5.4.7.txt[1.5.4.7],
 149  link:RelNotes-1.5.4.6.txt[1.5.4.6],
 150  link:RelNotes-1.5.4.5.txt[1.5.4.5],
 151  link:RelNotes-1.5.4.4.txt[1.5.4.4],
 152  link:RelNotes-1.5.4.3.txt[1.5.4.3],
 153  link:RelNotes-1.5.4.2.txt[1.5.4.2],
 154  link:RelNotes-1.5.4.1.txt[1.5.4.1],
 155  link:RelNotes-1.5.4.txt[1.5.4].
 156
 157* link:v1.5.3.8/git.html[documentation for release 1.5.3.8]
 158
 159* release notes for
 160  link:RelNotes-1.5.3.8.txt[1.5.3.8],
 161  link:RelNotes-1.5.3.7.txt[1.5.3.7],
 162  link:RelNotes-1.5.3.6.txt[1.5.3.6],
 163  link:RelNotes-1.5.3.5.txt[1.5.3.5],
 164  link:RelNotes-1.5.3.4.txt[1.5.3.4],
 165  link:RelNotes-1.5.3.3.txt[1.5.3.3],
 166  link:RelNotes-1.5.3.2.txt[1.5.3.2],
 167  link:RelNotes-1.5.3.1.txt[1.5.3.1],
 168  link:RelNotes-1.5.3.txt[1.5.3].
 169
 170* link:v1.5.2.5/git.html[documentation for release 1.5.2.5]
 171
 172* release notes for
 173  link:RelNotes-1.5.2.5.txt[1.5.2.5],
 174  link:RelNotes-1.5.2.4.txt[1.5.2.4],
 175  link:RelNotes-1.5.2.3.txt[1.5.2.3],
 176  link:RelNotes-1.5.2.2.txt[1.5.2.2],
 177  link:RelNotes-1.5.2.1.txt[1.5.2.1],
 178  link:RelNotes-1.5.2.txt[1.5.2].
 179
 180* link:v1.5.1.6/git.html[documentation for release 1.5.1.6]
 181
 182* release notes for
 183  link:RelNotes-1.5.1.6.txt[1.5.1.6],
 184  link:RelNotes-1.5.1.5.txt[1.5.1.5],
 185  link:RelNotes-1.5.1.4.txt[1.5.1.4],
 186  link:RelNotes-1.5.1.3.txt[1.5.1.3],
 187  link:RelNotes-1.5.1.2.txt[1.5.1.2],
 188  link:RelNotes-1.5.1.1.txt[1.5.1.1],
 189  link:RelNotes-1.5.1.txt[1.5.1].
 190
 191* link:v1.5.0.7/git.html[documentation for release 1.5.0.7]
 192
 193* release notes for
 194  link:RelNotes-1.5.0.7.txt[1.5.0.7],
 195  link:RelNotes-1.5.0.6.txt[1.5.0.6],
 196  link:RelNotes-1.5.0.5.txt[1.5.0.5],
 197  link:RelNotes-1.5.0.3.txt[1.5.0.3],
 198  link:RelNotes-1.5.0.2.txt[1.5.0.2],
 199  link:RelNotes-1.5.0.1.txt[1.5.0.1],
 200  link:RelNotes-1.5.0.txt[1.5.0].
 201
 202* documentation for release link:v1.4.4.4/git.html[1.4.4.4],
 203  link:v1.3.3/git.html[1.3.3],
 204  link:v1.2.6/git.html[1.2.6],
 205  link:v1.0.13/git.html[1.0.13].
 206
 207============
 208
 209endif::stalenotes[]
 210
 211OPTIONS
 212-------
 213--version::
 214        Prints the git suite version that the 'git' program came from.
 215
 216--help::
 217        Prints the synopsis and a list of the most commonly used
 218        commands. If the option '--all' or '-a' is given then all
 219        available commands are printed. If a git command is named this
 220        option will bring up the manual page for that command.
 221+
 222Other options are available to control how the manual page is
 223displayed. See linkgit:git-help[1] for more information,
 224because `git --help ...` is converted internally into `git
 225help ...`.
 226
 227--exec-path::
 228        Path to wherever your core git programs are installed.
 229        This can also be controlled by setting the GIT_EXEC_PATH
 230        environment variable. If no path is given, 'git' will print
 231        the current setting and then exit.
 232
 233--html-path::
 234        Print the path to wherever your git HTML documentation is installed
 235        and exit.
 236
 237-p::
 238--paginate::
 239        Pipe all output into 'less' (or if set, $PAGER) if standard
 240        output is a terminal.  This overrides the `pager.<cmd>`
 241        configuration options (see the "Configuration Mechanism" section
 242        below).
 243
 244--no-pager::
 245        Do not pipe git output into a pager.
 246
 247--git-dir=<path>::
 248        Set the path to the repository. This can also be controlled by
 249        setting the GIT_DIR environment variable. It can be an absolute
 250        path or relative path to current working directory.
 251
 252--work-tree=<path>::
 253        Set the path to the working tree.  The value will not be
 254        used in combination with repositories found automatically in
 255        a .git directory (i.e. $GIT_DIR is not set).
 256        This can also be controlled by setting the GIT_WORK_TREE
 257        environment variable and the core.worktree configuration
 258        variable. It can be an absolute path or relative path to
 259        the directory specified by --git-dir or GIT_DIR.
 260        Note: If --git-dir or GIT_DIR are specified but none of
 261        --work-tree, GIT_WORK_TREE and core.worktree is specified,
 262        the current working directory is regarded as the top directory
 263        of your working tree.
 264
 265--bare::
 266        Treat the repository as a bare repository.  If GIT_DIR
 267        environment is not set, it is set to the current working
 268        directory.
 269
 270--no-replace-objects::
 271        Do not use replacement refs to replace git objects. See
 272        linkgit:git-replace[1] for more information.
 273
 274
 275FURTHER DOCUMENTATION
 276---------------------
 277
 278See the references above to get started using git.  The following is
 279probably more detail than necessary for a first-time user.
 280
 281The link:user-manual.html#git-concepts[git concepts chapter of the
 282user-manual] and linkgit:gitcore-tutorial[7] both provide
 283introductions to the underlying git architecture.
 284
 285See linkgit:gitworkflows[7] for an overview of recommended workflows.
 286
 287See also the link:howto-index.html[howto] documents for some useful
 288examples.
 289
 290The internals are documented in the
 291link:technical/api-index.html[GIT API documentation].
 292
 293GIT COMMANDS
 294------------
 295
 296We divide git into high level ("porcelain") commands and low level
 297("plumbing") commands.
 298
 299High-level commands (porcelain)
 300-------------------------------
 301
 302We separate the porcelain commands into the main commands and some
 303ancillary user utilities.
 304
 305Main porcelain commands
 306~~~~~~~~~~~~~~~~~~~~~~~
 307
 308include::cmds-mainporcelain.txt[]
 309
 310Ancillary Commands
 311~~~~~~~~~~~~~~~~~~
 312Manipulators:
 313
 314include::cmds-ancillarymanipulators.txt[]
 315
 316Interrogators:
 317
 318include::cmds-ancillaryinterrogators.txt[]
 319
 320
 321Interacting with Others
 322~~~~~~~~~~~~~~~~~~~~~~~
 323
 324These commands are to interact with foreign SCM and with other
 325people via patch over e-mail.
 326
 327include::cmds-foreignscminterface.txt[]
 328
 329
 330Low-level commands (plumbing)
 331-----------------------------
 332
 333Although git includes its
 334own porcelain layer, its low-level commands are sufficient to support
 335development of alternative porcelains.  Developers of such porcelains
 336might start by reading about linkgit:git-update-index[1] and
 337linkgit:git-read-tree[1].
 338
 339The interface (input, output, set of options and the semantics)
 340to these low-level commands are meant to be a lot more stable
 341than Porcelain level commands, because these commands are
 342primarily for scripted use.  The interface to Porcelain commands
 343on the other hand are subject to change in order to improve the
 344end user experience.
 345
 346The following description divides
 347the low-level commands into commands that manipulate objects (in
 348the repository, index, and working tree), commands that interrogate and
 349compare objects, and commands that move objects and references between
 350repositories.
 351
 352
 353Manipulation commands
 354~~~~~~~~~~~~~~~~~~~~~
 355
 356include::cmds-plumbingmanipulators.txt[]
 357
 358
 359Interrogation commands
 360~~~~~~~~~~~~~~~~~~~~~~
 361
 362include::cmds-plumbinginterrogators.txt[]
 363
 364In general, the interrogate commands do not touch the files in
 365the working tree.
 366
 367
 368Synching repositories
 369~~~~~~~~~~~~~~~~~~~~~
 370
 371include::cmds-synchingrepositories.txt[]
 372
 373The following are helper commands used by the above; end users
 374typically do not use them directly.
 375
 376include::cmds-synchelpers.txt[]
 377
 378
 379Internal helper commands
 380~~~~~~~~~~~~~~~~~~~~~~~~
 381
 382These are internal helper commands used by other commands; end
 383users typically do not use them directly.
 384
 385include::cmds-purehelpers.txt[]
 386
 387
 388Configuration Mechanism
 389-----------------------
 390
 391Starting from 0.99.9 (actually mid 0.99.8.GIT), `.git/config` file
 392is used to hold per-repository configuration options.  It is a
 393simple text file modeled after `.ini` format familiar to some
 394people.  Here is an example:
 395
 396------------
 397#
 398# A '#' or ';' character indicates a comment.
 399#
 400
 401; core variables
 402[core]
 403        ; Don't trust file modes
 404        filemode = false
 405
 406; user identity
 407[user]
 408        name = "Junio C Hamano"
 409        email = "junkio@twinsun.com"
 410
 411------------
 412
 413Various commands read from the configuration file and adjust
 414their operation accordingly.  See linkgit:git-config[1] for a
 415list.
 416
 417
 418Identifier Terminology
 419----------------------
 420<object>::
 421        Indicates the object name for any type of object.
 422
 423<blob>::
 424        Indicates a blob object name.
 425
 426<tree>::
 427        Indicates a tree object name.
 428
 429<commit>::
 430        Indicates a commit object name.
 431
 432<tree-ish>::
 433        Indicates a tree, commit or tag object name.  A
 434        command that takes a <tree-ish> argument ultimately wants to
 435        operate on a <tree> object but automatically dereferences
 436        <commit> and <tag> objects that point at a <tree>.
 437
 438<commit-ish>::
 439        Indicates a commit or tag object name.  A
 440        command that takes a <commit-ish> argument ultimately wants to
 441        operate on a <commit> object but automatically dereferences
 442        <tag> objects that point at a <commit>.
 443
 444<type>::
 445        Indicates that an object type is required.
 446        Currently one of: `blob`, `tree`, `commit`, or `tag`.
 447
 448<file>::
 449        Indicates a filename - almost always relative to the
 450        root of the tree structure `GIT_INDEX_FILE` describes.
 451
 452Symbolic Identifiers
 453--------------------
 454Any git command accepting any <object> can also use the following
 455symbolic notation:
 456
 457HEAD::
 458        indicates the head of the current branch (i.e. the
 459        contents of `$GIT_DIR/HEAD`).
 460
 461<tag>::
 462        a valid tag 'name'
 463        (i.e. the contents of `$GIT_DIR/refs/tags/<tag>`).
 464
 465<head>::
 466        a valid head 'name'
 467        (i.e. the contents of `$GIT_DIR/refs/heads/<head>`).
 468
 469For a more complete list of ways to spell object names, see
 470"SPECIFYING REVISIONS" section in linkgit:git-rev-parse[1].
 471
 472
 473File/Directory Structure
 474------------------------
 475
 476Please see the linkgit:gitrepository-layout[5] document.
 477
 478Read linkgit:githooks[5] for more details about each hook.
 479
 480Higher level SCMs may provide and manage additional information in the
 481`$GIT_DIR`.
 482
 483
 484Terminology
 485-----------
 486Please see linkgit:gitglossary[7].
 487
 488
 489Environment Variables
 490---------------------
 491Various git commands use the following environment variables:
 492
 493The git Repository
 494~~~~~~~~~~~~~~~~~~
 495These environment variables apply to 'all' core git commands. Nb: it
 496is worth noting that they may be used/overridden by SCMS sitting above
 497git so take care if using Cogito etc.
 498
 499'GIT_INDEX_FILE'::
 500        This environment allows the specification of an alternate
 501        index file. If not specified, the default of `$GIT_DIR/index`
 502        is used.
 503
 504'GIT_OBJECT_DIRECTORY'::
 505        If the object storage directory is specified via this
 506        environment variable then the sha1 directories are created
 507        underneath - otherwise the default `$GIT_DIR/objects`
 508        directory is used.
 509
 510'GIT_ALTERNATE_OBJECT_DIRECTORIES'::
 511        Due to the immutable nature of git objects, old objects can be
 512        archived into shared, read-only directories. This variable
 513        specifies a ":" separated (on Windows ";" separated) list
 514        of git object directories which can be used to search for git
 515        objects. New objects will not be written to these directories.
 516
 517'GIT_DIR'::
 518        If the 'GIT_DIR' environment variable is set then it
 519        specifies a path to use instead of the default `.git`
 520        for the base of the repository.
 521
 522'GIT_WORK_TREE'::
 523        Set the path to the working tree.  The value will not be
 524        used in combination with repositories found automatically in
 525        a .git directory (i.e. $GIT_DIR is not set).
 526        This can also be controlled by the '--work-tree' command line
 527        option and the core.worktree configuration variable.
 528
 529'GIT_CEILING_DIRECTORIES'::
 530        This should be a colon-separated list of absolute paths.
 531        If set, it is a list of directories that git should not chdir
 532        up into while looking for a repository directory.
 533        It will not exclude the current working directory or
 534        a GIT_DIR set on the command line or in the environment.
 535        (Useful for excluding slow-loading network directories.)
 536
 537git Commits
 538~~~~~~~~~~~
 539'GIT_AUTHOR_NAME'::
 540'GIT_AUTHOR_EMAIL'::
 541'GIT_AUTHOR_DATE'::
 542'GIT_COMMITTER_NAME'::
 543'GIT_COMMITTER_EMAIL'::
 544'GIT_COMMITTER_DATE'::
 545'EMAIL'::
 546        see linkgit:git-commit-tree[1]
 547
 548git Diffs
 549~~~~~~~~~
 550'GIT_DIFF_OPTS'::
 551        Only valid setting is "--unified=??" or "-u??" to set the
 552        number of context lines shown when a unified diff is created.
 553        This takes precedence over any "-U" or "--unified" option
 554        value passed on the git diff command line.
 555
 556'GIT_EXTERNAL_DIFF'::
 557        When the environment variable 'GIT_EXTERNAL_DIFF' is set, the
 558        program named by it is called, instead of the diff invocation
 559        described above.  For a path that is added, removed, or modified,
 560        'GIT_EXTERNAL_DIFF' is called with 7 parameters:
 561
 562        path old-file old-hex old-mode new-file new-hex new-mode
 563+
 564where:
 565
 566        <old|new>-file:: are files GIT_EXTERNAL_DIFF can use to read the
 567                         contents of <old|new>,
 568        <old|new>-hex:: are the 40-hexdigit SHA1 hashes,
 569        <old|new>-mode:: are the octal representation of the file modes.
 570
 571+
 572The file parameters can point at the user's working file
 573(e.g. `new-file` in "git-diff-files"), `/dev/null` (e.g. `old-file`
 574when a new file is added), or a temporary file (e.g. `old-file` in the
 575index).  'GIT_EXTERNAL_DIFF' should not worry about unlinking the
 576temporary file --- it is removed when 'GIT_EXTERNAL_DIFF' exits.
 577+
 578For a path that is unmerged, 'GIT_EXTERNAL_DIFF' is called with 1
 579parameter, <path>.
 580
 581other
 582~~~~~
 583'GIT_MERGE_VERBOSITY'::
 584        A number controlling the amount of output shown by
 585        the recursive merge strategy.  Overrides merge.verbosity.
 586        See linkgit:git-merge[1]
 587
 588'GIT_PAGER'::
 589        This environment variable overrides `$PAGER`. If it is set
 590        to an empty string or to the value "cat", git will not launch
 591        a pager.  See also the `core.pager` option in
 592        linkgit:git-config[1].
 593
 594'GIT_SSH'::
 595        If this environment variable is set then 'git fetch'
 596        and 'git push' will use this command instead
 597        of 'ssh' when they need to connect to a remote system.
 598        The '$GIT_SSH' command will be given exactly two arguments:
 599        the 'username@host' (or just 'host') from the URL and the
 600        shell command to execute on that remote system.
 601+
 602To pass options to the program that you want to list in GIT_SSH
 603you will need to wrap the program and options into a shell script,
 604then set GIT_SSH to refer to the shell script.
 605+
 606Usually it is easier to configure any desired options through your
 607personal `.ssh/config` file.  Please consult your ssh documentation
 608for further details.
 609
 610'GIT_FLUSH'::
 611        If this environment variable is set to "1", then commands such
 612        as 'git blame' (in incremental mode), 'git rev-list', 'git log',
 613        and 'git whatchanged' will force a flush of the output stream
 614        after each commit-oriented record have been flushed.   If this
 615        variable is set to "0", the output of these commands will be done
 616        using completely buffered I/O.   If this environment variable is
 617        not set, git will choose buffered or record-oriented flushing
 618        based on whether stdout appears to be redirected to a file or not.
 619
 620'GIT_TRACE'::
 621        If this variable is set to "1", "2" or "true" (comparison
 622        is case insensitive), git will print `trace:` messages on
 623        stderr telling about alias expansion, built-in command
 624        execution and external command execution.
 625        If this variable is set to an integer value greater than 1
 626        and lower than 10 (strictly) then git will interpret this
 627        value as an open file descriptor and will try to write the
 628        trace messages into this file descriptor.
 629        Alternatively, if this variable is set to an absolute path
 630        (starting with a '/' character), git will interpret this
 631        as a file path and will try to write the trace messages
 632        into it.
 633
 634Discussion[[Discussion]]
 635------------------------
 636
 637More detail on the following is available from the
 638link:user-manual.html#git-concepts[git concepts chapter of the
 639user-manual] and linkgit:gitcore-tutorial[7].
 640
 641A git project normally consists of a working directory with a ".git"
 642subdirectory at the top level.  The .git directory contains, among other
 643things, a compressed object database representing the complete history
 644of the project, an "index" file which links that history to the current
 645contents of the working tree, and named pointers into that history such
 646as tags and branch heads.
 647
 648The object database contains objects of three main types: blobs, which
 649hold file data; trees, which point to blobs and other trees to build up
 650directory hierarchies; and commits, which each reference a single tree
 651and some number of parent commits.
 652
 653The commit, equivalent to what other systems call a "changeset" or
 654"version", represents a step in the project's history, and each parent
 655represents an immediately preceding step.  Commits with more than one
 656parent represent merges of independent lines of development.
 657
 658All objects are named by the SHA1 hash of their contents, normally
 659written as a string of 40 hex digits.  Such names are globally unique.
 660The entire history leading up to a commit can be vouched for by signing
 661just that commit.  A fourth object type, the tag, is provided for this
 662purpose.
 663
 664When first created, objects are stored in individual files, but for
 665efficiency may later be compressed together into "pack files".
 666
 667Named pointers called refs mark interesting points in history.  A ref
 668may contain the SHA1 name of an object or the name of another ref.  Refs
 669with names beginning `ref/head/` contain the SHA1 name of the most
 670recent commit (or "head") of a branch under development.  SHA1 names of
 671tags of interest are stored under `ref/tags/`.  A special ref named
 672`HEAD` contains the name of the currently checked-out branch.
 673
 674The index file is initialized with a list of all paths and, for each
 675path, a blob object and a set of attributes.  The blob object represents
 676the contents of the file as of the head of the current branch.  The
 677attributes (last modified time, size, etc.) are taken from the
 678corresponding file in the working tree.  Subsequent changes to the
 679working tree can be found by comparing these attributes.  The index may
 680be updated with new content, and new commits may be created from the
 681content stored in the index.
 682
 683The index is also capable of storing multiple entries (called "stages")
 684for a given pathname.  These stages are used to hold the various
 685unmerged version of a file when a merge is in progress.
 686
 687Authors
 688-------
 689* git's founding father is Linus Torvalds <torvalds@osdl.org>.
 690* The current git nurse is Junio C Hamano <gitster@pobox.com>.
 691* The git potty was written by Andreas Ericsson <ae@op5.se>.
 692* General upbringing is handled by the git-list <git@vger.kernel.org>.
 693
 694Documentation
 695--------------
 696The documentation for git suite was started by David Greaves
 697<david@dgreaves.com>, and later enhanced greatly by the
 698contributors on the git-list <git@vger.kernel.org>.
 699
 700SEE ALSO
 701--------
 702linkgit:gittutorial[7], linkgit:gittutorial-2[7],
 703link:everyday.html[Everyday Git], linkgit:gitcvs-migration[7],
 704linkgit:gitglossary[7], linkgit:gitcore-tutorial[7],
 705linkgit:gitcli[7], link:user-manual.html[The Git User's Manual],
 706linkgit:gitworkflows[7]
 707
 708GIT
 709---
 710Part of the linkgit:git[1] suite