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diff --git a/Documentation/glossary.txt b/Documentation/glossary.txt new file mode 100644 index 000000000..bac3c532f --- /dev/null +++ b/Documentation/glossary.txt @@ -0,0 +1,198 @@ +object:: + The unit of storage in GIT. It is uniquely identified by + the SHA1 of its contents. Consequently, an object can not + be changed. + +SHA1:: + 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). + +tree:: + 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). + +cache:: + 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). + +index:: + 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" + +directory:: + The list you get with "ls" :-) + +checkout:: + The action of updating the working tree to a revision which was + stored in the object database. + +revision:: + A particular state of files and directories which was stored in + the object database. It is referenced by a commit object. + +commit:: + 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. + +changeset:: + 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. + +ent:: + Favorite synonym to "tree-ish" by some total geeks. + +clean:: + A working tree is clean, if it corresponds to the revision + referenced by the current head. + +dirty:: + A working tree is said to be dirty if it contains modifications + which have not been committed to the current branch. + +head:: + The top of a branch. It contains a ref to the corresponding + commit object. + +branch:: + 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/. + +ref:: + 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/. + +tree-ish:: + 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". + +tag:: + 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). + +merge:: + 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. + +resolve:: + The action of fixing up manually what a failed automatic merge + left behind. + +repository:: + 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". + +reachable:: + An object is reachable from a ref/commit/tree/tag, if there is a + chain leading from the latter to the former. + +chain:: + 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). + +parent:: + A commit object contains a (possibly empty) list of the logical + predecessor(s) in the line of development, i.e. its parents. + +fetch:: + 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. + +pull:: + Pulling a branch means to fetch it and merge it. + +push:: + 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. + +pack:: + 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. + +plumbing:: + Cute name for core git. + +porcelain:: + 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. + +SCM:: + Source code management (tool). + +dircache:: + You are *waaaaay* behind. |