path: root/Documentation/glossary.txt
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authorJohannes Schindelin <>2005-08-17 14:56:48 (GMT)
committerJunio C Hamano <>2005-08-17 20:50:40 (GMT)
commitda139813a7242f96e6926fd15881b9df94625132 (patch)
treec1c7eb1683887a79471db666e584e15344a8fb97 /Documentation/glossary.txt
parentf01c0fceef2b14c04b1e927626473d059aecf453 (diff)
[PATCH] Add GIT glossary
[jc: This is the version without asciidoc cross references; Johannes says that the cross referenced one is generated from this file using a Perl script, so I am placing this as the source, and expecting to later receive the script and a Makefile entry or two to massage this file into the final HTML or whatever form.] Signed-off-by: Johannes Schindelin <> Signed-off-by: Junio C Hamano <>
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+ The unit of storage in GIT. It is uniquely identified by
+ the SHA1 of its contents. Consequently, an object can not
+ be changed.
+ A 20-byte sequence (or 41-byte file containing the hex
+ representation and a newline). It is calculated from the
+ contents of an object by the Secure Hash Algorithm 1.
+object database::
+ Stores a set of "objects", and an individial object is identified
+ by its SHA1 (its ref). The objects are either stored as single
+ files, or live inside of packs.
+object name::
+ Synonym for SHA1.
+blob object::
+ Untyped object, i.e. the contents of a file.
+tree object::
+ An object containing a list of blob and/or tree objects.
+ (A tree usually corresponds to a directory without
+ subdirectories).
+ Either a working tree, or a tree object together with the
+ dependent blob and tree objects (i.e. a stored representation
+ of a working tree).
+ A collection of files whose contents are stored as objects.
+ The cache is a stored version of your working tree. Well, can
+ also contain a second, and even a third version of a working
+ tree, which are used when merging.
+cache entry::
+ The information regarding a particular file, stored in the index.
+ A cache entry can be unmerged, if a merge was started, but not
+ yet finished (i.e. if the cache contains multiple versions of
+ that file).
+ Contains information about the cache contents, in particular
+ timestamps and mode flags ("stat information") for the files
+ stored in the cache. An unmerged index is an index which contains
+ unmerged cache entries.
+working tree::
+ The set of files and directories currently being worked on.
+ Think "ls -laR"
+ The list you get with "ls" :-)
+ The action of updating the working tree to a revision which was
+ stored in the object database.
+ A particular state of files and directories which was stored in
+ the object database. It is referenced by a commit object.
+ The action of storing the current state of the cache in the
+ object database. The result is a revision.
+commit object::
+ An object which contains the information about a particular
+ revision, such as parents, committer, author, date and the
+ tree object which corresponds to the top directory of the
+ stored revision.
+ BitKeeper/cvsps speak for "commit". Since git does not store
+ changes, but states, it really does not make sense to use
+ the term "changesets" with git.
+ Favorite synonym to "tree-ish" by some total geeks.
+ A working tree is clean, if it corresponds to the revision
+ referenced by the current head.
+ A working tree is said to be dirty if it contains modifications
+ which have not been committed to the current branch.
+ The top of a branch. It contains a ref to the corresponding
+ commit object.
+ A non-cyclical graph of revisions, i.e. the complete history of
+ a particular revision, which does not (yet) have children, which
+ is called the branch head. The branch heads are stored in
+ $GIT_DIR/refs/heads/.
+ A 40-byte hex representation of a SHA1 pointing to a particular
+ object. These are stored in $GIT_DIR/refs/.
+head ref::
+ A ref pointing to a head. Often, this is abbreviated to "head".
+ Head refs are stored in $GIT_DIR/refs/heads/.
+ A ref pointing to either a commit object, a tree object, or a
+ tag object pointing to a commit or tree object.
+tag object::
+ An object containing a ref pointing to another object. It can
+ contain a (PGP) signature, in which case it is called "signed
+ tag object".
+ A ref pointing to a tag or commit object. In contrast to a head,
+ a tag is not changed by a commit. Tags (not tag objects) are
+ stored in $GIT_DIR/refs/tags/. A git tag has nothing to do with
+ a Lisp tag (which is called object type in git's context).
+ To merge branches means to try to accumulate the changes since a
+ common ancestor and apply them to the first branch. An automatic
+ merge uses heuristics to accomplish that. Evidently, an automatic
+ merge can fail.
+ The action of fixing up manually what a failed automatic merge
+ left behind.
+ A collection of refs together with an object database containing
+ all objects, which are reachable from the refs. A repository can
+ share an object database with other repositories.
+alternate object database::
+ Via the alternates mechanism, a repository can inherit part of its
+ object database from another object database, which is called
+ "alternate".
+ An object is reachable from a ref/commit/tree/tag, if there is a
+ chain leading from the latter to the former.
+ A list of objects, where each object in the list contains a
+ reference to its successor (for example, the successor of a commit
+ could be one of its parents).
+ A commit object contains a (possibly empty) list of the logical
+ predecessor(s) in the line of development, i.e. its parents.
+ Fetching a branch means to get the branch's head ref from a
+ remote repository, to find out which objects are missing from
+ the local object database, and to get them, too.
+ Pulling a branch means to fetch it and merge it.
+ Pushing a branch means to get the branch's head ref from a remote
+ repository, find out if it is an ancestor to the branch's local
+ head ref is a direct, and in that case, putting all objects, which
+ are reachable from the local head ref, and which are missing from
+ the remote repository, into the remote object database, and updating
+ the remote head ref. If the remote head is not an ancestor to the
+ local head, the push fails.
+ A set of objects which have been compressed into one file (to save
+ space or to transmit them efficiently).
+pack index::
+ Contains offsets into a pack, so the pack can be used instead of
+ the unpacked objects.
+ Cute name for core git.
+ Cute name for programs and program suites depending on core git,
+ presenting a high level access to core git. Porcelains expose
+ more of a SCM interface than the plumbing.
+object type:
+ One of the identifiers "commit","tree","tag" and "blob" describing
+ the type of an object.
+ Source code management (tool).
+ You are *waaaaay* behind.