Documentation / glossary.txton commit Create/delete branch ref logs. (3a4b3f2)
   1alternate object database::
   2        Via the alternates mechanism, a repository can inherit part of its
   3        object database from another object database, which is called
   4        "alternate".
   5
   6bare repository::
   7        A bare repository is normally an appropriately named
   8        directory with a `.git` suffix that does not have a
   9        locally checked-out copy of any of the files under revision
  10        control.  That is, all of the `git` administrative and
  11        control files that would normally be present in the
  12        hidden `.git` sub-directory are directly present in
  13        the `repository.git` directory instead, and no other files
  14        are present and checked out.  Usually publishers of public
  15        repositories make bare repositories available.
  16
  17blob object::
  18        Untyped object, e.g. the contents of a file.
  19
  20branch::
  21        A non-cyclical graph of revisions, i.e. the complete history of
  22        a particular revision, which is called the branch head. The
  23        branch heads are stored in `$GIT_DIR/refs/heads/`.
  24
  25cache::
  26        Obsolete for: index.
  27
  28chain::
  29        A list of objects, where each object in the list contains a
  30        reference to its successor (for example, the successor of a commit
  31        could be one of its parents).
  32
  33changeset::
  34        BitKeeper/cvsps speak for "commit". Since git does not store
  35        changes, but states, it really does not make sense to use
  36        the term "changesets" with git.
  37
  38checkout::
  39        The action of updating the working tree to a revision which was
  40        stored in the object database.
  41
  42cherry-picking::
  43        In SCM jargon, "cherry pick" means to choose a subset of
  44        changes out of a series of changes (typically commits)
  45        and record them as a new series of changes on top of
  46        different codebase.  In GIT, this is performed by
  47        "git cherry-pick" command to extract the change
  48        introduced by an existing commit and to record it based
  49        on the tip of the current branch as a new commit.
  50
  51clean::
  52        A working tree is clean, if it corresponds to the revision
  53        referenced by the current head.  Also see "dirty".
  54
  55commit::
  56        As a verb: The action of storing the current state of the index in the
  57        object database. The result is a revision.
  58        As a noun: Short hand for commit object.
  59
  60commit object::
  61        An object which contains the information about a particular
  62        revision, such as parents, committer, author, date and the
  63        tree object which corresponds to the top directory of the
  64        stored revision.
  65
  66core git::
  67        Fundamental data structures and utilities of git. Exposes only
  68        limited source code management tools.
  69
  70DAG::
  71        Directed acyclic graph. The commit objects form a directed acyclic
  72        graph, because they have parents (directed), and the graph of commit
  73        objects is acyclic (there is no chain which begins and ends with the
  74        same object).
  75
  76dircache::
  77        You are *waaaaay* behind.
  78
  79dirty::
  80        A working tree is said to be dirty if it contains modifications
  81        which have not been committed to the current branch.
  82
  83directory::
  84        The list you get with "ls" :-)
  85
  86ent::
  87        Favorite synonym to "tree-ish" by some total geeks. See
  88        `http://en.wikipedia.org/wiki/Ent_(Middle-earth)` for an in-depth
  89        explanation.
  90
  91fast forward::
  92        A fast-forward is a special type of merge where you have
  93        a revision and you are "merging" another branch's changes
  94        that happen to be a descendant of what you have.
  95        In such these cases, you do not make a new merge commit but
  96        instead just update to his revision. This will happen
  97        frequently on a tracking branch of a remote repository.
  98
  99fetch::
 100        Fetching a branch means to get the branch's head ref from a
 101        remote repository, to find out which objects are missing from
 102        the local object database, and to get them, too.
 103
 104file system::
 105        Linus Torvalds originally designed git to be a user space file
 106        system, i.e. the infrastructure to hold files and directories.
 107        That ensured the efficiency and speed of git.
 108
 109git archive::
 110        Synonym for repository (for arch people).
 111
 112hash::
 113        In git's context, synonym to object name.
 114
 115head::
 116        The top of a branch. It contains a ref to the corresponding
 117        commit object.
 118
 119head ref::
 120        A ref pointing to a head. Often, this is abbreviated to "head".
 121        Head refs are stored in `$GIT_DIR/refs/heads/`.
 122
 123hook::
 124        During the normal execution of several git commands,
 125        call-outs are made to optional scripts that allow
 126        a developer to add functionality or checking.
 127        Typically, the hooks allow for a command to be pre-verified
 128        and potentially aborted, and allow for a post-notification
 129        after the operation is done.
 130        The hook scripts are found in the `$GIT_DIR/hooks/` directory,
 131        and are enabled by simply making them executable.
 132
 133index::
 134        A collection of files with stat information, whose contents are
 135        stored as objects. The index is a stored version of your working
 136        tree. Truth be told, it can also contain a second, and even a third
 137        version of a working tree, which are used when merging.
 138
 139index entry::
 140        The information regarding a particular file, stored in the index.
 141        An index entry can be unmerged, if a merge was started, but not
 142        yet finished (i.e. if the index contains multiple versions of
 143        that file).
 144
 145master::
 146        The default development branch. Whenever you create a git
 147        repository, a branch named "master" is created, and becomes
 148        the active branch. In most cases, this contains the local
 149        development, though that is purely conventional and not required.
 150
 151merge::
 152        To merge branches means to try to accumulate the changes since a
 153        common ancestor and apply them to the first branch. An automatic
 154        merge uses heuristics to accomplish that. Evidently, an automatic
 155        merge can fail.
 156
 157object::
 158        The unit of storage in git. It is uniquely identified by
 159        the SHA1 of its contents. Consequently, an object can not
 160        be changed.
 161
 162object database::
 163        Stores a set of "objects", and an individual object is identified
 164        by its object name. The objects usually live in `$GIT_DIR/objects/`.
 165
 166object identifier::
 167        Synonym for object name.
 168
 169object name::
 170        The unique identifier of an object. The hash of the object's contents
 171        using the Secure Hash Algorithm 1 and usually represented by the 40
 172        character hexadecimal encoding of the hash of the object (possibly
 173        followed by a white space).
 174
 175object type:
 176        One of the identifiers "commit","tree","tag" and "blob" describing
 177        the type of an object.
 178
 179octopus::
 180        To merge more than two branches. Also denotes an intelligent
 181        predator.
 182
 183origin::
 184        The default upstream tracking branch. Most projects have at
 185        least one upstream project which they track. By default
 186        'origin' is used for that purpose.  New upstream updates
 187        will be fetched into this branch; you should never commit
 188        to it yourself.
 189
 190pack::
 191        A set of objects which have been compressed into one file (to save
 192        space or to transmit them efficiently).
 193
 194pack index::
 195        The list of identifiers, and other information, of the objects in a
 196        pack, to assist in efficiently accessing the contents of a pack.
 197
 198parent::
 199        A commit object contains a (possibly empty) list of the logical
 200        predecessor(s) in the line of development, i.e. its parents.
 201
 202pickaxe::
 203        The term pickaxe refers to an option to the diffcore routines
 204        that help select changes that add or delete a given text string.
 205        With the --pickaxe-all option, it can be used to view the
 206        full changeset that introduced or removed, say, a particular
 207        line of text.  See gitlink:git-diff[1].
 208
 209plumbing::
 210        Cute name for core git.
 211
 212porcelain::
 213        Cute name for programs and program suites depending on core git,
 214        presenting a high level access to core git. Porcelains expose
 215        more of a SCM interface than the plumbing.
 216
 217pull::
 218        Pulling a branch means to fetch it and merge it.
 219
 220push::
 221        Pushing a branch means to get the branch's head ref from a remote
 222        repository, find out if it is an ancestor to the branch's local
 223        head ref is a direct, and in that case, putting all objects, which
 224        are reachable from the local head ref, and which are missing from
 225        the remote repository, into the remote object database, and updating
 226        the remote head ref. If the remote head is not an ancestor to the
 227        local head, the push fails.
 228
 229reachable::
 230        An object is reachable from a ref/commit/tree/tag, if there is a
 231        chain leading from the latter to the former.
 232
 233rebase::
 234        To clean a branch by starting from the head of the main line of
 235        development ("master"), and reapply the (possibly cherry-picked)
 236        changes from that branch.
 237
 238ref::
 239        A 40-byte hex representation of a SHA1 or a name that denotes
 240        a particular object. These may be stored in `$GIT_DIR/refs/`.
 241
 242refspec::
 243        A refspec is used by fetch and push to describe the mapping
 244        between remote ref and local ref.  They are combined with
 245        a colon in the format <src>:<dst>, preceded by an optional
 246        plus sign, +.  For example:
 247        `git fetch $URL refs/heads/master:refs/heads/origin`
 248        means "grab the master branch head from the $URL and store
 249        it as my origin branch head".
 250        And `git push $URL refs/heads/master:refs/heads/to-upstream`
 251        means "publish my master branch head as to-upstream master head
 252        at $URL".   See also gitlink:git-push[1]
 253
 254repository::
 255        A collection of refs together with an object database containing
 256        all objects, which are reachable from the refs, possibly accompanied
 257        by meta data from one or more porcelains. A repository can
 258        share an object database with other repositories.
 259
 260resolve::
 261        The action of fixing up manually what a failed automatic merge
 262        left behind.
 263
 264revision::
 265        A particular state of files and directories which was stored in
 266        the object database. It is referenced by a commit object.
 267
 268rewind::
 269        To throw away part of the development, i.e. to assign the head to
 270        an earlier revision.
 271
 272SCM::
 273        Source code management (tool).
 274
 275SHA1::
 276        Synonym for object name.
 277
 278topic branch::
 279        A regular git branch that is used by a developer to
 280        identify a conceptual line of development.  Since branches
 281        are very easy and inexpensive, it is often desirable to
 282        have several small branches that each contain very well
 283        defined concepts or small incremental yet related changes.
 284
 285tracking branch::
 286        A regular git branch that is used to follow changes from
 287        another repository.  A tracking branch should not contain
 288        direct modifications or have local commits made to it.
 289        A tracking branch can usually be identified as the
 290        right-hand-side ref in a Pull: refspec.
 291
 292tree object::
 293        An object containing a list of file names and modes along with refs
 294        to the associated blob and/or tree objects. A tree is equivalent
 295        to a directory.
 296
 297tree::
 298        Either a working tree, or a tree object together with the
 299        dependent blob and tree objects (i.e. a stored representation
 300        of a working tree).
 301
 302tree-ish::
 303        A ref pointing to either a commit object, a tree object, or a
 304        tag object pointing to a tag or commit or tree object.
 305
 306tag object::
 307        An object containing a ref pointing to another object, which can
 308        contain a message just like a commit object. It can also
 309        contain a (PGP) signature, in which case it is called a "signed
 310        tag object".
 311
 312tag::
 313        A ref pointing to a tag or commit object. In contrast to a head,
 314        a tag is not changed by a commit. Tags (not tag objects) are
 315        stored in `$GIT_DIR/refs/tags/`. A git tag has nothing to do with
 316        a Lisp tag (which is called object type in git's context).
 317        A tag is most typically used to mark a particular point in the
 318        commit ancestry chain.
 319
 320unmerged index:
 321        An index which contains unmerged index entries.
 322
 323working tree::
 324        The set of files and directories currently being worked on,
 325        i.e. you can work in your working tree without using git at all.
 326