Documentation / git.txton commit Merge branch 'jc/t9129-any-utf8' (f159bdd)
   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:v1.7.1/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:v1.7.0.6/git.html[documentation for release 1.7.0.6]
  53
  54* release notes for
  55  link:RelNotes-1.7.0.6.txt[1.7.0.6],
  56  link:RelNotes-1.7.0.5.txt[1.7.0.5],
  57  link:RelNotes-1.7.0.4.txt[1.7.0.4],
  58  link:RelNotes-1.7.0.3.txt[1.7.0.3],
  59  link:RelNotes-1.7.0.2.txt[1.7.0.2],
  60  link:RelNotes-1.7.0.1.txt[1.7.0.1],
  61  link:RelNotes-1.7.0.txt[1.7.0].
  62
  63* link:v1.6.6.2/git.html[documentation for release 1.6.6.2]
  64
  65* release notes for
  66  link:RelNotes-1.6.6.2.txt[1.6.6.2],
  67  link:RelNotes-1.6.6.1.txt[1.6.6.1],
  68  link:RelNotes-1.6.6.txt[1.6.6].
  69
  70* link:v1.6.5.8/git.html[documentation for release 1.6.5.8]
  71
  72* release notes for
  73  link:RelNotes-1.6.5.8.txt[1.6.5.8],
  74  link:RelNotes-1.6.5.7.txt[1.6.5.7],
  75  link:RelNotes-1.6.5.6.txt[1.6.5.6],
  76  link:RelNotes-1.6.5.5.txt[1.6.5.5],
  77  link:RelNotes-1.6.5.4.txt[1.6.5.4],
  78  link:RelNotes-1.6.5.3.txt[1.6.5.3],
  79  link:RelNotes-1.6.5.2.txt[1.6.5.2],
  80  link:RelNotes-1.6.5.1.txt[1.6.5.1],
  81  link:RelNotes-1.6.5.txt[1.6.5].
  82
  83* link:v1.6.4.4/git.html[documentation for release 1.6.4.4]
  84
  85* release notes for
  86  link:RelNotes-1.6.4.4.txt[1.6.4.4],
  87  link:RelNotes-1.6.4.3.txt[1.6.4.3],
  88  link:RelNotes-1.6.4.2.txt[1.6.4.2],
  89  link:RelNotes-1.6.4.1.txt[1.6.4.1],
  90  link:RelNotes-1.6.4.txt[1.6.4].
  91
  92* link:v1.6.3.4/git.html[documentation for release 1.6.3.4]
  93
  94* release notes for
  95  link:RelNotes-1.6.3.4.txt[1.6.3.4],
  96  link:RelNotes-1.6.3.3.txt[1.6.3.3],
  97  link:RelNotes-1.6.3.2.txt[1.6.3.2],
  98  link:RelNotes-1.6.3.1.txt[1.6.3.1],
  99  link:RelNotes-1.6.3.txt[1.6.3].
 100
 101* release notes for
 102  link:RelNotes-1.6.2.5.txt[1.6.2.5],
 103  link:RelNotes-1.6.2.4.txt[1.6.2.4],
 104  link:RelNotes-1.6.2.3.txt[1.6.2.3],
 105  link:RelNotes-1.6.2.2.txt[1.6.2.2],
 106  link:RelNotes-1.6.2.1.txt[1.6.2.1],
 107  link:RelNotes-1.6.2.txt[1.6.2].
 108
 109* link:v1.6.1.3/git.html[documentation for release 1.6.1.3]
 110
 111* release notes for
 112  link:RelNotes-1.6.1.3.txt[1.6.1.3],
 113  link:RelNotes-1.6.1.2.txt[1.6.1.2],
 114  link:RelNotes-1.6.1.1.txt[1.6.1.1],
 115  link:RelNotes-1.6.1.txt[1.6.1].
 116
 117* link:v1.6.0.6/git.html[documentation for release 1.6.0.6]
 118
 119* release notes for
 120  link:RelNotes-1.6.0.6.txt[1.6.0.6],
 121  link:RelNotes-1.6.0.5.txt[1.6.0.5],
 122  link:RelNotes-1.6.0.4.txt[1.6.0.4],
 123  link:RelNotes-1.6.0.3.txt[1.6.0.3],
 124  link:RelNotes-1.6.0.2.txt[1.6.0.2],
 125  link:RelNotes-1.6.0.1.txt[1.6.0.1],
 126  link:RelNotes-1.6.0.txt[1.6.0].
 127
 128* link:v1.5.6.6/git.html[documentation for release 1.5.6.6]
 129
 130* release notes for
 131  link:RelNotes-1.5.6.6.txt[1.5.6.6],
 132  link:RelNotes-1.5.6.5.txt[1.5.6.5],
 133  link:RelNotes-1.5.6.4.txt[1.5.6.4],
 134  link:RelNotes-1.5.6.3.txt[1.5.6.3],
 135  link:RelNotes-1.5.6.2.txt[1.5.6.2],
 136  link:RelNotes-1.5.6.1.txt[1.5.6.1],
 137  link:RelNotes-1.5.6.txt[1.5.6].
 138
 139* link:v1.5.5.6/git.html[documentation for release 1.5.5.6]
 140
 141* release notes for
 142  link:RelNotes-1.5.5.6.txt[1.5.5.6],
 143  link:RelNotes-1.5.5.5.txt[1.5.5.5],
 144  link:RelNotes-1.5.5.4.txt[1.5.5.4],
 145  link:RelNotes-1.5.5.3.txt[1.5.5.3],
 146  link:RelNotes-1.5.5.2.txt[1.5.5.2],
 147  link:RelNotes-1.5.5.1.txt[1.5.5.1],
 148  link:RelNotes-1.5.5.txt[1.5.5].
 149
 150* link:v1.5.4.7/git.html[documentation for release 1.5.4.7]
 151
 152* release notes for
 153  link:RelNotes-1.5.4.7.txt[1.5.4.7],
 154  link:RelNotes-1.5.4.6.txt[1.5.4.6],
 155  link:RelNotes-1.5.4.5.txt[1.5.4.5],
 156  link:RelNotes-1.5.4.4.txt[1.5.4.4],
 157  link:RelNotes-1.5.4.3.txt[1.5.4.3],
 158  link:RelNotes-1.5.4.2.txt[1.5.4.2],
 159  link:RelNotes-1.5.4.1.txt[1.5.4.1],
 160  link:RelNotes-1.5.4.txt[1.5.4].
 161
 162* link:v1.5.3.8/git.html[documentation for release 1.5.3.8]
 163
 164* release notes for
 165  link:RelNotes-1.5.3.8.txt[1.5.3.8],
 166  link:RelNotes-1.5.3.7.txt[1.5.3.7],
 167  link:RelNotes-1.5.3.6.txt[1.5.3.6],
 168  link:RelNotes-1.5.3.5.txt[1.5.3.5],
 169  link:RelNotes-1.5.3.4.txt[1.5.3.4],
 170  link:RelNotes-1.5.3.3.txt[1.5.3.3],
 171  link:RelNotes-1.5.3.2.txt[1.5.3.2],
 172  link:RelNotes-1.5.3.1.txt[1.5.3.1],
 173  link:RelNotes-1.5.3.txt[1.5.3].
 174
 175* link:v1.5.2.5/git.html[documentation for release 1.5.2.5]
 176
 177* release notes for
 178  link:RelNotes-1.5.2.5.txt[1.5.2.5],
 179  link:RelNotes-1.5.2.4.txt[1.5.2.4],
 180  link:RelNotes-1.5.2.3.txt[1.5.2.3],
 181  link:RelNotes-1.5.2.2.txt[1.5.2.2],
 182  link:RelNotes-1.5.2.1.txt[1.5.2.1],
 183  link:RelNotes-1.5.2.txt[1.5.2].
 184
 185* link:v1.5.1.6/git.html[documentation for release 1.5.1.6]
 186
 187* release notes for
 188  link:RelNotes-1.5.1.6.txt[1.5.1.6],
 189  link:RelNotes-1.5.1.5.txt[1.5.1.5],
 190  link:RelNotes-1.5.1.4.txt[1.5.1.4],
 191  link:RelNotes-1.5.1.3.txt[1.5.1.3],
 192  link:RelNotes-1.5.1.2.txt[1.5.1.2],
 193  link:RelNotes-1.5.1.1.txt[1.5.1.1],
 194  link:RelNotes-1.5.1.txt[1.5.1].
 195
 196* link:v1.5.0.7/git.html[documentation for release 1.5.0.7]
 197
 198* release notes for
 199  link:RelNotes-1.5.0.7.txt[1.5.0.7],
 200  link:RelNotes-1.5.0.6.txt[1.5.0.6],
 201  link:RelNotes-1.5.0.5.txt[1.5.0.5],
 202  link:RelNotes-1.5.0.3.txt[1.5.0.3],
 203  link:RelNotes-1.5.0.2.txt[1.5.0.2],
 204  link:RelNotes-1.5.0.1.txt[1.5.0.1],
 205  link:RelNotes-1.5.0.txt[1.5.0].
 206
 207* documentation for release link:v1.4.4.4/git.html[1.4.4.4],
 208  link:v1.3.3/git.html[1.3.3],
 209  link:v1.2.6/git.html[1.2.6],
 210  link:v1.0.13/git.html[1.0.13].
 211
 212============
 213
 214endif::stalenotes[]
 215
 216OPTIONS
 217-------
 218--version::
 219        Prints the git suite version that the 'git' program came from.
 220
 221--help::
 222        Prints the synopsis and a list of the most commonly used
 223        commands. If the option '--all' or '-a' is given then all
 224        available commands are printed. If a git command is named this
 225        option will bring up the manual page for that command.
 226+
 227Other options are available to control how the manual page is
 228displayed. See linkgit:git-help[1] for more information,
 229because `git --help ...` is converted internally into `git
 230help ...`.
 231
 232-c <name>=<value>::
 233        Pass a configuration parameter to the command. The value
 234        given will override values from configuration files.
 235        The <name> is expected in the same format as listed by
 236        'git config' (subkeys separated by dots).
 237
 238--exec-path::
 239        Path to wherever your core git programs are installed.
 240        This can also be controlled by setting the GIT_EXEC_PATH
 241        environment variable. If no path is given, 'git' will print
 242        the current setting and then exit.
 243
 244--html-path::
 245        Print the path to wherever your git HTML documentation is installed
 246        and exit.
 247
 248-p::
 249--paginate::
 250        Pipe all output into 'less' (or if set, $PAGER) if standard
 251        output is a terminal.  This overrides the `pager.<cmd>`
 252        configuration options (see the "Configuration Mechanism" section
 253        below).
 254
 255--no-pager::
 256        Do not pipe git output into a pager.
 257
 258--git-dir=<path>::
 259        Set the path to the repository. This can also be controlled by
 260        setting the GIT_DIR environment variable. It can be an absolute
 261        path or relative path to current working directory.
 262
 263--work-tree=<path>::
 264        Set the path to the working tree.  The value will not be
 265        used in combination with repositories found automatically in
 266        a .git directory (i.e. $GIT_DIR is not set).
 267        This can also be controlled by setting the GIT_WORK_TREE
 268        environment variable and the core.worktree configuration
 269        variable. It can be an absolute path or relative path to
 270        the directory specified by --git-dir or GIT_DIR.
 271        Note: If --git-dir or GIT_DIR are specified but none of
 272        --work-tree, GIT_WORK_TREE and core.worktree is specified,
 273        the current working directory is regarded as the top directory
 274        of your working tree.
 275
 276--bare::
 277        Treat the repository as a bare repository.  If GIT_DIR
 278        environment is not set, it is set to the current working
 279        directory.
 280
 281--no-replace-objects::
 282        Do not use replacement refs to replace git objects. See
 283        linkgit:git-replace[1] for more information.
 284
 285
 286FURTHER DOCUMENTATION
 287---------------------
 288
 289See the references above to get started using git.  The following is
 290probably more detail than necessary for a first-time user.
 291
 292The link:user-manual.html#git-concepts[git concepts chapter of the
 293user-manual] and linkgit:gitcore-tutorial[7] both provide
 294introductions to the underlying git architecture.
 295
 296See linkgit:gitworkflows[7] for an overview of recommended workflows.
 297
 298See also the link:howto-index.html[howto] documents for some useful
 299examples.
 300
 301The internals are documented in the
 302link:technical/api-index.html[GIT API documentation].
 303
 304GIT COMMANDS
 305------------
 306
 307We divide git into high level ("porcelain") commands and low level
 308("plumbing") commands.
 309
 310High-level commands (porcelain)
 311-------------------------------
 312
 313We separate the porcelain commands into the main commands and some
 314ancillary user utilities.
 315
 316Main porcelain commands
 317~~~~~~~~~~~~~~~~~~~~~~~
 318
 319include::cmds-mainporcelain.txt[]
 320
 321Ancillary Commands
 322~~~~~~~~~~~~~~~~~~
 323Manipulators:
 324
 325include::cmds-ancillarymanipulators.txt[]
 326
 327Interrogators:
 328
 329include::cmds-ancillaryinterrogators.txt[]
 330
 331
 332Interacting with Others
 333~~~~~~~~~~~~~~~~~~~~~~~
 334
 335These commands are to interact with foreign SCM and with other
 336people via patch over e-mail.
 337
 338include::cmds-foreignscminterface.txt[]
 339
 340
 341Low-level commands (plumbing)
 342-----------------------------
 343
 344Although git includes its
 345own porcelain layer, its low-level commands are sufficient to support
 346development of alternative porcelains.  Developers of such porcelains
 347might start by reading about linkgit:git-update-index[1] and
 348linkgit:git-read-tree[1].
 349
 350The interface (input, output, set of options and the semantics)
 351to these low-level commands are meant to be a lot more stable
 352than Porcelain level commands, because these commands are
 353primarily for scripted use.  The interface to Porcelain commands
 354on the other hand are subject to change in order to improve the
 355end user experience.
 356
 357The following description divides
 358the low-level commands into commands that manipulate objects (in
 359the repository, index, and working tree), commands that interrogate and
 360compare objects, and commands that move objects and references between
 361repositories.
 362
 363
 364Manipulation commands
 365~~~~~~~~~~~~~~~~~~~~~
 366
 367include::cmds-plumbingmanipulators.txt[]
 368
 369
 370Interrogation commands
 371~~~~~~~~~~~~~~~~~~~~~~
 372
 373include::cmds-plumbinginterrogators.txt[]
 374
 375In general, the interrogate commands do not touch the files in
 376the working tree.
 377
 378
 379Synching repositories
 380~~~~~~~~~~~~~~~~~~~~~
 381
 382include::cmds-synchingrepositories.txt[]
 383
 384The following are helper commands used by the above; end users
 385typically do not use them directly.
 386
 387include::cmds-synchelpers.txt[]
 388
 389
 390Internal helper commands
 391~~~~~~~~~~~~~~~~~~~~~~~~
 392
 393These are internal helper commands used by other commands; end
 394users typically do not use them directly.
 395
 396include::cmds-purehelpers.txt[]
 397
 398
 399Configuration Mechanism
 400-----------------------
 401
 402Starting from 0.99.9 (actually mid 0.99.8.GIT), `.git/config` file
 403is used to hold per-repository configuration options.  It is a
 404simple text file modeled after `.ini` format familiar to some
 405people.  Here is an example:
 406
 407------------
 408#
 409# A '#' or ';' character indicates a comment.
 410#
 411
 412; core variables
 413[core]
 414        ; Don't trust file modes
 415        filemode = false
 416
 417; user identity
 418[user]
 419        name = "Junio C Hamano"
 420        email = "junkio@twinsun.com"
 421
 422------------
 423
 424Various commands read from the configuration file and adjust
 425their operation accordingly.  See linkgit:git-config[1] for a
 426list.
 427
 428
 429Identifier Terminology
 430----------------------
 431<object>::
 432        Indicates the object name for any type of object.
 433
 434<blob>::
 435        Indicates a blob object name.
 436
 437<tree>::
 438        Indicates a tree object name.
 439
 440<commit>::
 441        Indicates a commit object name.
 442
 443<tree-ish>::
 444        Indicates a tree, commit or tag object name.  A
 445        command that takes a <tree-ish> argument ultimately wants to
 446        operate on a <tree> object but automatically dereferences
 447        <commit> and <tag> objects that point at a <tree>.
 448
 449<commit-ish>::
 450        Indicates a commit or tag object name.  A
 451        command that takes a <commit-ish> argument ultimately wants to
 452        operate on a <commit> object but automatically dereferences
 453        <tag> objects that point at a <commit>.
 454
 455<type>::
 456        Indicates that an object type is required.
 457        Currently one of: `blob`, `tree`, `commit`, or `tag`.
 458
 459<file>::
 460        Indicates a filename - almost always relative to the
 461        root of the tree structure `GIT_INDEX_FILE` describes.
 462
 463Symbolic Identifiers
 464--------------------
 465Any git command accepting any <object> can also use the following
 466symbolic notation:
 467
 468HEAD::
 469        indicates the head of the current branch (i.e. the
 470        contents of `$GIT_DIR/HEAD`).
 471
 472<tag>::
 473        a valid tag 'name'
 474        (i.e. the contents of `$GIT_DIR/refs/tags/<tag>`).
 475
 476<head>::
 477        a valid head 'name'
 478        (i.e. the contents of `$GIT_DIR/refs/heads/<head>`).
 479
 480For a more complete list of ways to spell object names, see
 481"SPECIFYING REVISIONS" section in linkgit:git-rev-parse[1].
 482
 483
 484File/Directory Structure
 485------------------------
 486
 487Please see the linkgit:gitrepository-layout[5] document.
 488
 489Read linkgit:githooks[5] for more details about each hook.
 490
 491Higher level SCMs may provide and manage additional information in the
 492`$GIT_DIR`.
 493
 494
 495Terminology
 496-----------
 497Please see linkgit:gitglossary[7].
 498
 499
 500Environment Variables
 501---------------------
 502Various git commands use the following environment variables:
 503
 504The git Repository
 505~~~~~~~~~~~~~~~~~~
 506These environment variables apply to 'all' core git commands. Nb: it
 507is worth noting that they may be used/overridden by SCMS sitting above
 508git so take care if using Cogito etc.
 509
 510'GIT_INDEX_FILE'::
 511        This environment allows the specification of an alternate
 512        index file. If not specified, the default of `$GIT_DIR/index`
 513        is used.
 514
 515'GIT_OBJECT_DIRECTORY'::
 516        If the object storage directory is specified via this
 517        environment variable then the sha1 directories are created
 518        underneath - otherwise the default `$GIT_DIR/objects`
 519        directory is used.
 520
 521'GIT_ALTERNATE_OBJECT_DIRECTORIES'::
 522        Due to the immutable nature of git objects, old objects can be
 523        archived into shared, read-only directories. This variable
 524        specifies a ":" separated (on Windows ";" separated) list
 525        of git object directories which can be used to search for git
 526        objects. New objects will not be written to these directories.
 527
 528'GIT_DIR'::
 529        If the 'GIT_DIR' environment variable is set then it
 530        specifies a path to use instead of the default `.git`
 531        for the base of the repository.
 532
 533'GIT_WORK_TREE'::
 534        Set the path to the working tree.  The value will not be
 535        used in combination with repositories found automatically in
 536        a .git directory (i.e. $GIT_DIR is not set).
 537        This can also be controlled by the '--work-tree' command line
 538        option and the core.worktree configuration variable.
 539
 540'GIT_CEILING_DIRECTORIES'::
 541        This should be a colon-separated list of absolute paths.
 542        If set, it is a list of directories that git should not chdir
 543        up into while looking for a repository directory.
 544        It will not exclude the current working directory or
 545        a GIT_DIR set on the command line or in the environment.
 546        (Useful for excluding slow-loading network directories.)
 547
 548'GIT_DISCOVERY_ACROSS_FILESYSTEM'::
 549        When run in a directory that does not have ".git" repository
 550        directory, git tries to find such a directory in the parent
 551        directories to find the top of the working tree, but by default it
 552        does not cross filesystem boundaries.  This environment variable
 553        can be set to true to tell git not to stop at filesystem
 554        boundaries.  Like 'GIT_CEILING_DIRECTORIES', this will not affect
 555        an explicit repository directory set via 'GIT_DIR' or on the
 556        command line.
 557
 558git Commits
 559~~~~~~~~~~~
 560'GIT_AUTHOR_NAME'::
 561'GIT_AUTHOR_EMAIL'::
 562'GIT_AUTHOR_DATE'::
 563'GIT_COMMITTER_NAME'::
 564'GIT_COMMITTER_EMAIL'::
 565'GIT_COMMITTER_DATE'::
 566'EMAIL'::
 567        see linkgit:git-commit-tree[1]
 568
 569git Diffs
 570~~~~~~~~~
 571'GIT_DIFF_OPTS'::
 572        Only valid setting is "--unified=??" or "-u??" to set the
 573        number of context lines shown when a unified diff is created.
 574        This takes precedence over any "-U" or "--unified" option
 575        value passed on the git diff command line.
 576
 577'GIT_EXTERNAL_DIFF'::
 578        When the environment variable 'GIT_EXTERNAL_DIFF' is set, the
 579        program named by it is called, instead of the diff invocation
 580        described above.  For a path that is added, removed, or modified,
 581        'GIT_EXTERNAL_DIFF' is called with 7 parameters:
 582
 583        path old-file old-hex old-mode new-file new-hex new-mode
 584+
 585where:
 586
 587        <old|new>-file:: are files GIT_EXTERNAL_DIFF can use to read the
 588                         contents of <old|new>,
 589        <old|new>-hex:: are the 40-hexdigit SHA1 hashes,
 590        <old|new>-mode:: are the octal representation of the file modes.
 591
 592+
 593The file parameters can point at the user's working file
 594(e.g. `new-file` in "git-diff-files"), `/dev/null` (e.g. `old-file`
 595when a new file is added), or a temporary file (e.g. `old-file` in the
 596index).  'GIT_EXTERNAL_DIFF' should not worry about unlinking the
 597temporary file --- it is removed when 'GIT_EXTERNAL_DIFF' exits.
 598+
 599For a path that is unmerged, 'GIT_EXTERNAL_DIFF' is called with 1
 600parameter, <path>.
 601
 602other
 603~~~~~
 604'GIT_MERGE_VERBOSITY'::
 605        A number controlling the amount of output shown by
 606        the recursive merge strategy.  Overrides merge.verbosity.
 607        See linkgit:git-merge[1]
 608
 609'GIT_PAGER'::
 610        This environment variable overrides `$PAGER`. If it is set
 611        to an empty string or to the value "cat", git will not launch
 612        a pager.  See also the `core.pager` option in
 613        linkgit:git-config[1].
 614
 615'GIT_SSH'::
 616        If this environment variable is set then 'git fetch'
 617        and 'git push' will use this command instead
 618        of 'ssh' when they need to connect to a remote system.
 619        The '$GIT_SSH' command will be given exactly two arguments:
 620        the 'username@host' (or just 'host') from the URL and the
 621        shell command to execute on that remote system.
 622+
 623To pass options to the program that you want to list in GIT_SSH
 624you will need to wrap the program and options into a shell script,
 625then set GIT_SSH to refer to the shell script.
 626+
 627Usually it is easier to configure any desired options through your
 628personal `.ssh/config` file.  Please consult your ssh documentation
 629for further details.
 630
 631'GIT_FLUSH'::
 632        If this environment variable is set to "1", then commands such
 633        as 'git blame' (in incremental mode), 'git rev-list', 'git log',
 634        and 'git whatchanged' will force a flush of the output stream
 635        after each commit-oriented record have been flushed.   If this
 636        variable is set to "0", the output of these commands will be done
 637        using completely buffered I/O.   If this environment variable is
 638        not set, git will choose buffered or record-oriented flushing
 639        based on whether stdout appears to be redirected to a file or not.
 640
 641'GIT_TRACE'::
 642        If this variable is set to "1", "2" or "true" (comparison
 643        is case insensitive), git will print `trace:` messages on
 644        stderr telling about alias expansion, built-in command
 645        execution and external command execution.
 646        If this variable is set to an integer value greater than 1
 647        and lower than 10 (strictly) then git will interpret this
 648        value as an open file descriptor and will try to write the
 649        trace messages into this file descriptor.
 650        Alternatively, if this variable is set to an absolute path
 651        (starting with a '/' character), git will interpret this
 652        as a file path and will try to write the trace messages
 653        into it.
 654
 655Discussion[[Discussion]]
 656------------------------
 657
 658More detail on the following is available from the
 659link:user-manual.html#git-concepts[git concepts chapter of the
 660user-manual] and linkgit:gitcore-tutorial[7].
 661
 662A git project normally consists of a working directory with a ".git"
 663subdirectory at the top level.  The .git directory contains, among other
 664things, a compressed object database representing the complete history
 665of the project, an "index" file which links that history to the current
 666contents of the working tree, and named pointers into that history such
 667as tags and branch heads.
 668
 669The object database contains objects of three main types: blobs, which
 670hold file data; trees, which point to blobs and other trees to build up
 671directory hierarchies; and commits, which each reference a single tree
 672and some number of parent commits.
 673
 674The commit, equivalent to what other systems call a "changeset" or
 675"version", represents a step in the project's history, and each parent
 676represents an immediately preceding step.  Commits with more than one
 677parent represent merges of independent lines of development.
 678
 679All objects are named by the SHA1 hash of their contents, normally
 680written as a string of 40 hex digits.  Such names are globally unique.
 681The entire history leading up to a commit can be vouched for by signing
 682just that commit.  A fourth object type, the tag, is provided for this
 683purpose.
 684
 685When first created, objects are stored in individual files, but for
 686efficiency may later be compressed together into "pack files".
 687
 688Named pointers called refs mark interesting points in history.  A ref
 689may contain the SHA1 name of an object or the name of another ref.  Refs
 690with names beginning `ref/head/` contain the SHA1 name of the most
 691recent commit (or "head") of a branch under development.  SHA1 names of
 692tags of interest are stored under `ref/tags/`.  A special ref named
 693`HEAD` contains the name of the currently checked-out branch.
 694
 695The index file is initialized with a list of all paths and, for each
 696path, a blob object and a set of attributes.  The blob object represents
 697the contents of the file as of the head of the current branch.  The
 698attributes (last modified time, size, etc.) are taken from the
 699corresponding file in the working tree.  Subsequent changes to the
 700working tree can be found by comparing these attributes.  The index may
 701be updated with new content, and new commits may be created from the
 702content stored in the index.
 703
 704The index is also capable of storing multiple entries (called "stages")
 705for a given pathname.  These stages are used to hold the various
 706unmerged version of a file when a merge is in progress.
 707
 708Authors
 709-------
 710* git's founding father is Linus Torvalds <torvalds@osdl.org>.
 711* The current git nurse is Junio C Hamano <gitster@pobox.com>.
 712* The git potty was written by Andreas Ericsson <ae@op5.se>.
 713* General upbringing is handled by the git-list <git@vger.kernel.org>.
 714
 715Documentation
 716--------------
 717The documentation for git suite was started by David Greaves
 718<david@dgreaves.com>, and later enhanced greatly by the
 719contributors on the git-list <git@vger.kernel.org>.
 720
 721SEE ALSO
 722--------
 723linkgit:gittutorial[7], linkgit:gittutorial-2[7],
 724link:everyday.html[Everyday Git], linkgit:gitcvs-migration[7],
 725linkgit:gitglossary[7], linkgit:gitcore-tutorial[7],
 726linkgit:gitcli[7], link:user-manual.html[The Git User's Manual],
 727linkgit:gitworkflows[7]
 728
 729GIT
 730---
 731Part of the linkgit:git[1] suite