Documentation / glossary-content.txton commit Git 1.9.1 (cee0c27)
   1[[def_alternate_object_database]]alternate object database::
   2        Via the alternates mechanism, a <<def_repository,repository>>
   3        can inherit part of its <<def_object_database,object database>>
   4        from another object database, which is called "alternate".
   5
   6[[def_bare_repository]]bare repository::
   7        A bare repository is normally an appropriately
   8        named <<def_directory,directory>> with a `.git` suffix that does not
   9        have a locally checked-out copy of any of the files under
  10        revision control. That is, all of the Git
  11        administrative and control files that would normally be present in the
  12        hidden `.git` sub-directory are directly present in the
  13        `repository.git` directory instead,
  14        and no other files are present and checked out. Usually publishers of
  15        public repositories make bare repositories available.
  16
  17[[def_blob_object]]blob object::
  18        Untyped <<def_object,object>>, e.g. the contents of a file.
  19
  20[[def_branch]]branch::
  21        A "branch" is an active line of development.  The most recent
  22        <<def_commit,commit>> on a branch is referred to as the tip of
  23        that branch.  The tip of the branch is referenced by a branch
  24        <<def_head,head>>, which moves forward as additional development
  25        is done on the branch.  A single Git
  26        <<def_repository,repository>> can track an arbitrary number of
  27        branches, but your <<def_working_tree,working tree>> is
  28        associated with just one of them (the "current" or "checked out"
  29        branch), and <<def_HEAD,HEAD>> points to that branch.
  30
  31[[def_cache]]cache::
  32        Obsolete for: <<def_index,index>>.
  33
  34[[def_chain]]chain::
  35        A list of objects, where each <<def_object,object>> in the list contains
  36        a reference to its successor (for example, the successor of a
  37        <<def_commit,commit>> could be one of its <<def_parent,parents>>).
  38
  39[[def_changeset]]changeset::
  40        BitKeeper/cvsps speak for "<<def_commit,commit>>". Since Git does not
  41        store changes, but states, it really does not make sense to use the term
  42        "changesets" with Git.
  43
  44[[def_checkout]]checkout::
  45        The action of updating all or part of the
  46        <<def_working_tree,working tree>> with a <<def_tree_object,tree object>>
  47        or <<def_blob_object,blob>> from the
  48        <<def_object_database,object database>>, and updating the
  49        <<def_index,index>> and <<def_HEAD,HEAD>> if the whole working tree has
  50        been pointed at a new <<def_branch,branch>>.
  51
  52[[def_cherry-picking]]cherry-picking::
  53        In <<def_SCM,SCM>> jargon, "cherry pick" means to choose a subset of
  54        changes out of a series of changes (typically commits) and record them
  55        as a new series of changes on top of a different codebase. In Git, this is
  56        performed by the "git cherry-pick" command to extract the change introduced
  57        by an existing <<def_commit,commit>> and to record it based on the tip
  58        of the current <<def_branch,branch>> as a new commit.
  59
  60[[def_clean]]clean::
  61        A <<def_working_tree,working tree>> is clean, if it
  62        corresponds to the <<def_revision,revision>> referenced by the current
  63        <<def_head,head>>. Also see "<<def_dirty,dirty>>".
  64
  65[[def_commit]]commit::
  66        As a noun: A single point in the
  67        Git history; the entire history of a project is represented as a
  68        set of interrelated commits.  The word "commit" is often
  69        used by Git in the same places other revision control systems
  70        use the words "revision" or "version".  Also used as a short
  71        hand for <<def_commit_object,commit object>>.
  72+
  73As a verb: The action of storing a new snapshot of the project's
  74state in the Git history, by creating a new commit representing the current
  75state of the <<def_index,index>> and advancing <<def_HEAD,HEAD>>
  76to point at the new commit.
  77
  78[[def_commit_object]]commit object::
  79        An <<def_object,object>> which contains the information about a
  80        particular <<def_revision,revision>>, such as <<def_parent,parents>>, committer,
  81        author, date and the <<def_tree_object,tree object>> which corresponds
  82        to the top <<def_directory,directory>> of the stored
  83        revision.
  84
  85[[def_commit-ish]]commit-ish (also committish)::
  86        A <<def_commit_object,commit object>> or an
  87        <<def_object,object>> that can be recursively dereferenced to
  88        a commit object.
  89        The following are all commit-ishes:
  90        a commit object,
  91        a <<def_tag_object,tag object>> that points to a commit
  92        object,
  93        a tag object that points to a tag object that points to a
  94        commit object,
  95        etc.
  96
  97[[def_core_git]]core Git::
  98        Fundamental data structures and utilities of Git. Exposes only limited
  99        source code management tools.
 100
 101[[def_DAG]]DAG::
 102        Directed acyclic graph. The <<def_commit_object,commit objects>> form a
 103        directed acyclic graph, because they have parents (directed), and the
 104        graph of commit objects is acyclic (there is no <<def_chain,chain>>
 105        which begins and ends with the same <<def_object,object>>).
 106
 107[[def_dangling_object]]dangling object::
 108        An <<def_unreachable_object,unreachable object>> which is not
 109        <<def_reachable,reachable>> even from other unreachable objects; a
 110        dangling object has no references to it from any
 111        reference or <<def_object,object>> in the <<def_repository,repository>>.
 112
 113[[def_detached_HEAD]]detached HEAD::
 114        Normally the <<def_HEAD,HEAD>> stores the name of a
 115        <<def_branch,branch>>, and commands that operate on the
 116        history HEAD represents operate on the history leading to the
 117        tip of the branch the HEAD points at.  However, Git also
 118        allows you to <<def_checkout,check out>> an arbitrary
 119        <<def_commit,commit>> that isn't necessarily the tip of any
 120        particular branch.  The HEAD in such a state is called
 121        "detached".
 122+
 123Note that commands that operate on the history of the current branch
 124(e.g. `git commit` to build a new history on top of it) still work
 125while the HEAD is detached. They update the HEAD to point at the tip
 126of the updated history without affecting any branch.  Commands that
 127update or inquire information _about_ the current branch (e.g. `git
 128branch --set-upstream-to` that sets what remote-tracking branch the
 129current branch integrates with) obviously do not work, as there is no
 130(real) current branch to ask about in this state.
 131
 132[[def_directory]]directory::
 133        The list you get with "ls" :-)
 134
 135[[def_dirty]]dirty::
 136        A <<def_working_tree,working tree>> is said to be "dirty" if
 137        it contains modifications which have not been <<def_commit,committed>> to the current
 138        <<def_branch,branch>>.
 139
 140[[def_evil_merge]]evil merge::
 141        An evil merge is a <<def_merge,merge>> that introduces changes that
 142        do not appear in any <<def_parent,parent>>.
 143
 144[[def_fast_forward]]fast-forward::
 145        A fast-forward is a special type of <<def_merge,merge>> where you have a
 146        <<def_revision,revision>> and you are "merging" another
 147        <<def_branch,branch>>'s changes that happen to be a descendant of what
 148        you have. In such these cases, you do not make a new <<def_merge,merge>>
 149        <<def_commit,commit>> but instead just update to his
 150        revision. This will happen frequently on a
 151        <<def_remote_tracking_branch,remote-tracking branch>> of a remote
 152        <<def_repository,repository>>.
 153
 154[[def_fetch]]fetch::
 155        Fetching a <<def_branch,branch>> means to get the
 156        branch's <<def_head_ref,head ref>> from a remote
 157        <<def_repository,repository>>, to find out which objects are
 158        missing from the local <<def_object_database,object database>>,
 159        and to get them, too.  See also linkgit:git-fetch[1].
 160
 161[[def_file_system]]file system::
 162        Linus Torvalds originally designed Git to be a user space file system,
 163        i.e. the infrastructure to hold files and directories. That ensured the
 164        efficiency and speed of Git.
 165
 166[[def_git_archive]]Git archive::
 167        Synonym for <<def_repository,repository>> (for arch people).
 168
 169[[def_gitfile]]gitfile::
 170        A plain file `.git` at the root of a working tree that
 171        points at the directory that is the real repository.
 172
 173[[def_grafts]]grafts::
 174        Grafts enables two otherwise different lines of development to be joined
 175        together by recording fake ancestry information for commits. This way
 176        you can make Git pretend the set of <<def_parent,parents>> a <<def_commit,commit>> has
 177        is different from what was recorded when the commit was
 178        created. Configured via the `.git/info/grafts` file.
 179
 180[[def_hash]]hash::
 181        In Git's context, synonym for <<def_object_name,object name>>.
 182
 183[[def_head]]head::
 184        A <<def_ref,named reference>> to the <<def_commit,commit>> at the tip of a
 185        <<def_branch,branch>>.  Heads are stored in a file in
 186        `$GIT_DIR/refs/heads/` directory, except when using packed refs. (See
 187        linkgit:git-pack-refs[1].)
 188
 189[[def_HEAD]]HEAD::
 190        The current <<def_branch,branch>>.  In more detail: Your <<def_working_tree,
 191        working tree>> is normally derived from the state of the tree
 192        referred to by HEAD.  HEAD is a reference to one of the
 193        <<def_head,heads>> in your repository, except when using a
 194        <<def_detached_HEAD,detached HEAD>>, in which case it directly
 195        references an arbitrary commit.
 196
 197[[def_head_ref]]head ref::
 198        A synonym for <<def_head,head>>.
 199
 200[[def_hook]]hook::
 201        During the normal execution of several Git commands, call-outs are made
 202        to optional scripts that allow a developer to add functionality or
 203        checking. Typically, the hooks allow for a command to be pre-verified
 204        and potentially aborted, and allow for a post-notification after the
 205        operation is done. The hook scripts are found in the
 206        `$GIT_DIR/hooks/` directory, and are enabled by simply
 207        removing the `.sample` suffix from the filename. In earlier versions
 208        of Git you had to make them executable.
 209
 210[[def_index]]index::
 211        A collection of files with stat information, whose contents are stored
 212        as objects. The index is a stored version of your
 213        <<def_working_tree,working tree>>. Truth be told, it can also contain a second, and even
 214        a third version of a working tree, which are used
 215        when <<def_merge,merging>>.
 216
 217[[def_index_entry]]index entry::
 218        The information regarding a particular file, stored in the
 219        <<def_index,index>>. An index entry can be unmerged, if a
 220        <<def_merge,merge>> was started, but not yet finished (i.e. if
 221        the index contains multiple versions of that file).
 222
 223[[def_master]]master::
 224        The default development <<def_branch,branch>>. Whenever you
 225        create a Git <<def_repository,repository>>, a branch named
 226        "master" is created, and becomes the active branch. In most
 227        cases, this contains the local development, though that is
 228        purely by convention and is not required.
 229
 230[[def_merge]]merge::
 231        As a verb: To bring the contents of another
 232        <<def_branch,branch>> (possibly from an external
 233        <<def_repository,repository>>) into the current branch.  In the
 234        case where the merged-in branch is from a different repository,
 235        this is done by first <<def_fetch,fetching>> the remote branch
 236        and then merging the result into the current branch.  This
 237        combination of fetch and merge operations is called a
 238        <<def_pull,pull>>.  Merging is performed by an automatic process
 239        that identifies changes made since the branches diverged, and
 240        then applies all those changes together.  In cases where changes
 241        conflict, manual intervention may be required to complete the
 242        merge.
 243+
 244As a noun: unless it is a <<def_fast_forward,fast-forward>>, a
 245successful merge results in the creation of a new <<def_commit,commit>>
 246representing the result of the merge, and having as
 247<<def_parent,parents>> the tips of the merged <<def_branch,branches>>.
 248This commit is referred to as a "merge commit", or sometimes just a
 249"merge".
 250
 251[[def_object]]object::
 252        The unit of storage in Git. It is uniquely identified by the
 253        <<def_SHA1,SHA-1>> of its contents. Consequently, an
 254        object can not be changed.
 255
 256[[def_object_database]]object database::
 257        Stores a set of "objects", and an individual <<def_object,object>> is
 258        identified by its <<def_object_name,object name>>. The objects usually
 259        live in `$GIT_DIR/objects/`.
 260
 261[[def_object_identifier]]object identifier::
 262        Synonym for <<def_object_name,object name>>.
 263
 264[[def_object_name]]object name::
 265        The unique identifier of an <<def_object,object>>.  The
 266        object name is usually represented by a 40 character
 267        hexadecimal string.  Also colloquially called <<def_SHA1,SHA-1>>.
 268
 269[[def_object_type]]object type::
 270        One of the identifiers "<<def_commit_object,commit>>",
 271        "<<def_tree_object,tree>>", "<<def_tag_object,tag>>" or
 272        "<<def_blob_object,blob>>" describing the type of an
 273        <<def_object,object>>.
 274
 275[[def_octopus]]octopus::
 276        To <<def_merge,merge>> more than two <<def_branch,branches>>.
 277
 278[[def_origin]]origin::
 279        The default upstream <<def_repository,repository>>. Most projects have
 280        at least one upstream project which they track. By default
 281        'origin' is used for that purpose. New upstream updates
 282        will be fetched into <<def_remote_tracking_branch,remote-tracking branches>> named
 283        origin/name-of-upstream-branch, which you can see using
 284        `git branch -r`.
 285
 286[[def_pack]]pack::
 287        A set of objects which have been compressed into one file (to save space
 288        or to transmit them efficiently).
 289
 290[[def_pack_index]]pack index::
 291        The list of identifiers, and other information, of the objects in a
 292        <<def_pack,pack>>, to assist in efficiently accessing the contents of a
 293        pack.
 294
 295[[def_pathspec]]pathspec::
 296        Pattern used to limit paths in Git commands.
 297+
 298Pathspecs are used on the command line of "git ls-files", "git
 299ls-tree", "git add", "git grep", "git diff", "git checkout",
 300and many other commands to
 301limit the scope of operations to some subset of the tree or
 302worktree.  See the documentation of each command for whether
 303paths are relative to the current directory or toplevel.  The
 304pathspec syntax is as follows:
 305+
 306--
 307
 308* any path matches itself
 309* the pathspec up to the last slash represents a
 310  directory prefix.  The scope of that pathspec is
 311  limited to that subtree.
 312* the rest of the pathspec is a pattern for the remainder
 313  of the pathname.  Paths relative to the directory
 314  prefix will be matched against that pattern using fnmatch(3);
 315  in particular, '*' and '?' _can_ match directory separators.
 316
 317--
 318+
 319For example, Documentation/*.jpg will match all .jpg files
 320in the Documentation subtree,
 321including Documentation/chapter_1/figure_1.jpg.
 322+
 323A pathspec that begins with a colon `:` has special meaning.  In the
 324short form, the leading colon `:` is followed by zero or more "magic
 325signature" letters (which optionally is terminated by another colon `:`),
 326and the remainder is the pattern to match against the path.
 327The "magic signature" consists of ASCII symbols that are neither
 328alphanumeric, glob, regex special charaters nor colon.
 329The optional colon that terminates the "magic signature" can be
 330omitted if the pattern begins with a character that does not belong to
 331"magic signature" symbol set and is not a colon.
 332+
 333In the long form, the leading colon `:` is followed by a open
 334parenthesis `(`, a comma-separated list of zero or more "magic words",
 335and a close parentheses `)`, and the remainder is the pattern to match
 336against the path.
 337+
 338A pathspec with only a colon means "there is no pathspec". This form
 339should not be combined with other pathspec.
 340+
 341--
 342top;;
 343        The magic word `top` (magic signature: `/`) makes the pattern
 344        match from the root of the working tree, even when you are
 345        running the command from inside a subdirectory.
 346
 347literal;;
 348        Wildcards in the pattern such as `*` or `?` are treated
 349        as literal characters.
 350
 351icase;;
 352        Case insensitive match.
 353
 354glob;;
 355        Git treats the pattern as a shell glob suitable for
 356        consumption by fnmatch(3) with the FNM_PATHNAME flag:
 357        wildcards in the pattern will not match a / in the pathname.
 358        For example, "Documentation/{asterisk}.html" matches
 359        "Documentation/git.html" but not "Documentation/ppc/ppc.html"
 360        or "tools/perf/Documentation/perf.html".
 361+
 362Two consecutive asterisks ("`**`") in patterns matched against
 363full pathname may have special meaning:
 364
 365 - A leading "`**`" followed by a slash means match in all
 366   directories. For example, "`**/foo`" matches file or directory
 367   "`foo`" anywhere, the same as pattern "`foo`". "`**/foo/bar`"
 368   matches file or directory "`bar`" anywhere that is directly
 369   under directory "`foo`".
 370
 371 - A trailing "`/**`" matches everything inside. For example,
 372   "`abc/**`" matches all files inside directory "abc", relative
 373   to the location of the `.gitignore` file, with infinite depth.
 374
 375 - A slash followed by two consecutive asterisks then a slash
 376   matches zero or more directories. For example, "`a/**/b`"
 377   matches "`a/b`", "`a/x/b`", "`a/x/y/b`" and so on.
 378
 379 - Other consecutive asterisks are considered invalid.
 380+
 381Glob magic is incompatible with literal magic.
 382
 383exclude;;
 384        After a path matches any non-exclude pathspec, it will be run
 385        through all exclude pathspec (magic signature: `!`). If it
 386        matches, the path is ignored.
 387--
 388
 389[[def_parent]]parent::
 390        A <<def_commit_object,commit object>> contains a (possibly empty) list
 391        of the logical predecessor(s) in the line of development, i.e. its
 392        parents.
 393
 394[[def_pickaxe]]pickaxe::
 395        The term <<def_pickaxe,pickaxe>> refers to an option to the diffcore
 396        routines that help select changes that add or delete a given text
 397        string. With the `--pickaxe-all` option, it can be used to view the full
 398        <<def_changeset,changeset>> that introduced or removed, say, a
 399        particular line of text. See linkgit:git-diff[1].
 400
 401[[def_plumbing]]plumbing::
 402        Cute name for <<def_core_git,core Git>>.
 403
 404[[def_porcelain]]porcelain::
 405        Cute name for programs and program suites depending on
 406        <<def_core_git,core Git>>, presenting a high level access to
 407        core Git. Porcelains expose more of a <<def_SCM,SCM>>
 408        interface than the <<def_plumbing,plumbing>>.
 409
 410[[def_pull]]pull::
 411        Pulling a <<def_branch,branch>> means to <<def_fetch,fetch>> it and
 412        <<def_merge,merge>> it.  See also linkgit:git-pull[1].
 413
 414[[def_push]]push::
 415        Pushing a <<def_branch,branch>> means to get the branch's
 416        <<def_head_ref,head ref>> from a remote <<def_repository,repository>>,
 417        find out if it is a direct ancestor to the branch's local
 418        head ref, and in that case, putting all
 419        objects, which are <<def_reachable,reachable>> from the local
 420        head ref, and which are missing from the remote
 421        repository, into the remote
 422        <<def_object_database,object database>>, and updating the remote
 423        head ref. If the remote <<def_head,head>> is not an
 424        ancestor to the local head, the push fails.
 425
 426[[def_reachable]]reachable::
 427        All of the ancestors of a given <<def_commit,commit>> are said to be
 428        "reachable" from that commit. More
 429        generally, one <<def_object,object>> is reachable from
 430        another if we can reach the one from the other by a <<def_chain,chain>>
 431        that follows <<def_tag,tags>> to whatever they tag,
 432        <<def_commit_object,commits>> to their parents or trees, and
 433        <<def_tree_object,trees>> to the trees or <<def_blob_object,blobs>>
 434        that they contain.
 435
 436[[def_rebase]]rebase::
 437        To reapply a series of changes from a <<def_branch,branch>> to a
 438        different base, and reset the <<def_head,head>> of that branch
 439        to the result.
 440
 441[[def_ref]]ref::
 442        A name that begins with `refs/` (e.g. `refs/heads/master`)
 443        that points to an <<def_object_name,object name>> or another
 444        ref (the latter is called a <<def_symref,symbolic ref>>).
 445        For convenience, a ref can sometimes be abbreviated when used
 446        as an argument to a Git command; see linkgit:gitrevisions[7]
 447        for details.
 448        Refs are stored in the <<def_repository,repository>>.
 449+
 450The ref namespace is hierarchical.
 451Different subhierarchies are used for different purposes (e.g. the
 452`refs/heads/` hierarchy is used to represent local branches).
 453+
 454There are a few special-purpose refs that do not begin with `refs/`.
 455The most notable example is `HEAD`.
 456
 457[[def_reflog]]reflog::
 458        A reflog shows the local "history" of a ref.  In other words,
 459        it can tell you what the 3rd last revision in _this_ repository
 460        was, and what was the current state in _this_ repository,
 461        yesterday 9:14pm.  See linkgit:git-reflog[1] for details.
 462
 463[[def_refspec]]refspec::
 464        A "refspec" is used by <<def_fetch,fetch>> and
 465        <<def_push,push>> to describe the mapping between remote
 466        <<def_ref,ref>> and local ref.
 467
 468[[def_remote_tracking_branch]]remote-tracking branch::
 469        A <<def_ref,ref>> that is used to follow changes from another
 470        <<def_repository,repository>>. It typically looks like
 471        'refs/remotes/foo/bar' (indicating that it tracks a branch named
 472        'bar' in a remote named 'foo'), and matches the right-hand-side of
 473        a configured fetch <<def_refspec,refspec>>. A remote-tracking
 474        branch should not contain direct modifications or have local
 475        commits made to it.
 476
 477[[def_repository]]repository::
 478        A collection of <<def_ref,refs>> together with an
 479        <<def_object_database,object database>> containing all objects
 480        which are <<def_reachable,reachable>> from the refs, possibly
 481        accompanied by meta data from one or more <<def_porcelain,porcelains>>. A
 482        repository can share an object database with other repositories
 483        via <<def_alternate_object_database,alternates mechanism>>.
 484
 485[[def_resolve]]resolve::
 486        The action of fixing up manually what a failed automatic
 487        <<def_merge,merge>> left behind.
 488
 489[[def_revision]]revision::
 490        Synonym for <<def_commit,commit>> (the noun).
 491
 492[[def_rewind]]rewind::
 493        To throw away part of the development, i.e. to assign the
 494        <<def_head,head>> to an earlier <<def_revision,revision>>.
 495
 496[[def_SCM]]SCM::
 497        Source code management (tool).
 498
 499[[def_SHA1]]SHA-1::
 500        "Secure Hash Algorithm 1"; a cryptographic hash function.
 501        In the context of Git used as a synonym for <<def_object_name,object name>>.
 502
 503[[def_shallow_repository]]shallow repository::
 504        A shallow <<def_repository,repository>> has an incomplete
 505        history some of whose <<def_commit,commits>> have <<def_parent,parents>> cauterized away (in other
 506        words, Git is told to pretend that these commits do not have the
 507        parents, even though they are recorded in the <<def_commit_object,commit
 508        object>>). This is sometimes useful when you are interested only in the
 509        recent history of a project even though the real history recorded in the
 510        upstream is much larger. A shallow repository
 511        is created by giving the `--depth` option to linkgit:git-clone[1], and
 512        its history can be later deepened with linkgit:git-fetch[1].
 513
 514[[def_symref]]symref::
 515        Symbolic reference: instead of containing the <<def_SHA1,SHA-1>>
 516        id itself, it is of the format 'ref: refs/some/thing' and when
 517        referenced, it recursively dereferences to this reference.
 518        '<<def_HEAD,HEAD>>' is a prime example of a symref. Symbolic
 519        references are manipulated with the linkgit:git-symbolic-ref[1]
 520        command.
 521
 522[[def_tag]]tag::
 523        A <<def_ref,ref>> under `refs/tags/` namespace that points to an
 524        object of an arbitrary type (typically a tag points to either a
 525        <<def_tag_object,tag>> or a <<def_commit_object,commit object>>).
 526        In contrast to a <<def_head,head>>, a tag is not updated by
 527        the `commit` command. A Git tag has nothing to do with a Lisp
 528        tag (which would be called an <<def_object_type,object type>>
 529        in Git's context). A tag is most typically used to mark a particular
 530        point in the commit ancestry <<def_chain,chain>>.
 531
 532[[def_tag_object]]tag object::
 533        An <<def_object,object>> containing a <<def_ref,ref>> pointing to
 534        another object, which can contain a message just like a
 535        <<def_commit_object,commit object>>. It can also contain a (PGP)
 536        signature, in which case it is called a "signed tag object".
 537
 538[[def_topic_branch]]topic branch::
 539        A regular Git <<def_branch,branch>> that is used by a developer to
 540        identify a conceptual line of development. Since branches are very easy
 541        and inexpensive, it is often desirable to have several small branches
 542        that each contain very well defined concepts or small incremental yet
 543        related changes.
 544
 545[[def_tree]]tree::
 546        Either a <<def_working_tree,working tree>>, or a <<def_tree_object,tree
 547        object>> together with the dependent <<def_blob_object,blob>> and tree objects
 548        (i.e. a stored representation of a working tree).
 549
 550[[def_tree_object]]tree object::
 551        An <<def_object,object>> containing a list of file names and modes along
 552        with refs to the associated blob and/or tree objects. A
 553        <<def_tree,tree>> is equivalent to a <<def_directory,directory>>.
 554
 555[[def_tree-ish]]tree-ish (also treeish)::
 556        A <<def_tree_object,tree object>> or an <<def_object,object>>
 557        that can be recursively dereferenced to a tree object.
 558        Dereferencing a <<def_commit_object,commit object>> yields the
 559        tree object corresponding to the <<def_revision,revision>>'s
 560        top <<def_directory,directory>>.
 561        The following are all tree-ishes:
 562        a <<def_commit-ish,commit-ish>>,
 563        a tree object,
 564        a <<def_tag_object,tag object>> that points to a tree object,
 565        a tag object that points to a tag object that points to a tree
 566        object,
 567        etc.
 568
 569[[def_unmerged_index]]unmerged index::
 570        An <<def_index,index>> which contains unmerged
 571        <<def_index_entry,index entries>>.
 572
 573[[def_unreachable_object]]unreachable object::
 574        An <<def_object,object>> which is not <<def_reachable,reachable>> from a
 575        <<def_branch,branch>>, <<def_tag,tag>>, or any other reference.
 576
 577[[def_upstream_branch]]upstream branch::
 578        The default <<def_branch,branch>> that is merged into the branch in
 579        question (or the branch in question is rebased onto). It is configured
 580        via branch.<name>.remote and branch.<name>.merge. If the upstream branch
 581        of 'A' is 'origin/B' sometimes we say "'A' is tracking 'origin/B'".
 582
 583[[def_working_tree]]working tree::
 584        The tree of actual checked out files.  The working tree normally
 585        contains the contents of the <<def_HEAD,HEAD>> commit's tree,
 586        plus any local changes that you have made but not yet committed.