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diff --git a/Documentation/glossary.txt b/Documentation/glossary.txt new file mode 100644 index 0000000000..9f446241e2 --- /dev/null +++ b/Documentation/glossary.txt @@ -0,0 +1,365 @@ +alternate object database:: + Via the alternates mechanism, a repository can inherit part of its + object database from another object database, which is called + "alternate". + +bare repository:: + A bare repository is normally an appropriately named + directory with a `.git` suffix that does not have a + locally checked-out copy of any of the files under revision + control. That is, all of the `git` administrative and + control files that would normally be present in the + hidden `.git` sub-directory are directly present in + the `repository.git` directory instead, and no other files + are present and checked out. Usually publishers of public + repositories make bare repositories available. + +blob object:: + Untyped object, e.g. the contents of a file. + +branch:: + A non-cyclical graph of revisions, i.e. the complete history of + a particular revision, which is called the branch head. The + branch heads are stored in `$GIT_DIR/refs/heads/`. + +cache:: + Obsolete for: index. + +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). + +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. + +checkout:: + The action of updating the working tree to a revision which was + stored in the object database. + +cherry-picking:: + In SCM jargon, "cherry pick" means to choose a subset of + changes out of a series of changes (typically commits) + and record them as a new series of changes on top of + different codebase. In GIT, this is performed by + "git cherry-pick" command to extract the change + introduced by an existing commit and to record it based + on the tip of the current branch as a new commit. + +clean:: + A working tree is clean, if it corresponds to the revision + referenced by the current head. Also see "dirty". + +commit:: + As a verb: The action of storing the current state of the index in the + object database. The result is a revision. + As a noun: Short hand for commit object. + +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. + +core git:: + Fundamental data structures and utilities of git. Exposes only + limited source code management tools. + +DAG:: + Directed acyclic graph. The commit objects form a directed acyclic + graph, because they have parents (directed), and the graph of commit + objects is acyclic (there is no chain which begins and ends with the + same object). + +dangling object:: + An unreachable object which is not reachable even from other + unreachable objects; a dangling object has no references to it + from any reference or object in the repository. + +dircache:: + You are *waaaaay* behind. + +dirty:: + A working tree is said to be dirty if it contains modifications + which have not been committed to the current branch. + +directory:: + The list you get with "ls" :-) + +ent:: + Favorite synonym to "tree-ish" by some total geeks. See + `http://en.wikipedia.org/wiki/Ent_(Middle-earth)` for an in-depth + explanation. Avoid this term, not to confuse people. + +fast forward:: + A fast-forward is a special type of merge where you have + a revision and you are "merging" another branch's changes + that happen to be a descendant of what you have. + In such these cases, you do not make a new merge commit but + instead just update to his revision. This will happen + frequently on a tracking branch of a remote repository. + +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. + +file system:: + Linus Torvalds originally designed git to be a user space file + system, i.e. the infrastructure to hold files and directories. + That ensured the efficiency and speed of git. + +git archive:: + Synonym for repository (for arch people). + +grafts:: + Grafts enables two otherwise different lines of development to be + joined together by recording fake ancestry information for commits. + This way you can make git pretend the set of parents a commit + has is different from what was recorded when the commit was created. + Configured via the `.git/info/grafts` file. + +hash:: + In git's context, synonym to object name. + +head:: + The top of a branch. It contains a ref to the corresponding + commit object. + +head ref:: + A ref pointing to a head. Often, this is abbreviated to "head". + Head refs are stored in `$GIT_DIR/refs/heads/`. + +hook:: + During the normal execution of several git commands, + call-outs are made to optional scripts that allow + a developer to add functionality or checking. + Typically, the hooks allow for a command to be pre-verified + and potentially aborted, and allow for a post-notification + after the operation is done. + The hook scripts are found in the `$GIT_DIR/hooks/` directory, + and are enabled by simply making them executable. + +index:: + A collection of files with stat information, whose contents are + stored as objects. The index is a stored version of your working + tree. Truth be told, it can also contain a second, and even a third + version of a working tree, which are used when merging. + +index entry:: + The information regarding a particular file, stored in the index. + An index entry can be unmerged, if a merge was started, but not + yet finished (i.e. if the index contains multiple versions of + that file). + +master:: + The default development branch. Whenever you create a git + repository, a branch named "master" is created, and becomes + the active branch. In most cases, this contains the local + development, though that is purely conventional and not required. + +merge:: + To merge branches means to try to accumulate the changes since a + common ancestor and apply them to the first branch. An automatic + merge uses heuristics to accomplish that. Evidently, an automatic + merge can fail. + +object:: + The unit of storage in git. It is uniquely identified by + the SHA1 of its contents. Consequently, an object can not + be changed. + +object database:: + Stores a set of "objects", and an individual object is identified + by its object name. The objects usually live in `$GIT_DIR/objects/`. + +object identifier:: + Synonym for object name. + +object name:: + The unique identifier of an object. The hash of the object's contents + using the Secure Hash Algorithm 1 and usually represented by the 40 + character hexadecimal encoding of the hash of the object (possibly + followed by a white space). + +object type:: + One of the identifiers "commit","tree","tag" and "blob" describing + the type of an object. + +octopus:: + To merge more than two branches. Also denotes an intelligent + predator. + +origin:: + The default upstream repository. Most projects have at + least one upstream project which they track. By default + 'origin' is used for that purpose. New upstream updates + will be fetched into remote tracking branches named + origin/name-of-upstream-branch, which you can see using + "git branch -r". + +pack:: + A set of objects which have been compressed into one file (to save + space or to transmit them efficiently). + +pack index:: + The list of identifiers, and other information, of the objects in a + pack, to assist in efficiently accessing the contents of a pack. + +parent:: + A commit object contains a (possibly empty) list of the logical + predecessor(s) in the line of development, i.e. its parents. + +pickaxe:: + The term pickaxe refers to an option to the diffcore routines + that help select changes that add or delete a given text string. + With the --pickaxe-all option, it can be used to view the + full changeset that introduced or removed, say, a particular + line of text. See gitlink:git-diff[1]. + +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. + +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. + +reachable:: + All of the ancestors of a given commit are said to be reachable from + that commit. More generally, one object is reachable from another if + we can reach the one from the other by a chain that follows tags to + whatever they tag, commits to their parents or trees, and trees to the + trees or blobs that they contain. + +rebase:: + To clean a branch by starting from the head of the main line of + development ("master"), and reapply the (possibly cherry-picked) + changes from that branch. + +ref:: + A 40-byte hex representation of a SHA1 or a name that denotes + a particular object. These may be stored in `$GIT_DIR/refs/`. + +refspec:: + A refspec is used by fetch and push to describe the mapping + between remote ref and local ref. They are combined with + a colon in the format <src>:<dst>, preceded by an optional + plus sign, +. For example: + `git fetch $URL refs/heads/master:refs/heads/origin` + means "grab the master branch head from the $URL and store + it as my origin branch head". + And `git push $URL refs/heads/master:refs/heads/to-upstream` + means "publish my master branch head as to-upstream branch + at $URL". See also gitlink:git-push[1] + +repository:: + A collection of refs together with an object database containing + all objects, which are reachable from the refs, possibly accompanied + by meta data from one or more porcelains. A repository can + share an object database with other repositories. + +resolve:: + The action of fixing up manually what a failed automatic merge + left behind. + +revision:: + A particular state of files and directories which was stored in + the object database. It is referenced by a commit object. + +rewind:: + To throw away part of the development, i.e. to assign the head to + an earlier revision. + +SCM:: + Source code management (tool). + +SHA1:: + Synonym for object name. + +shallow repository:: + A shallow repository has an incomplete history some of + whose commits have parents cauterized away (in other + words, git is told to pretend that these commits do not + have the parents, even though they are recorded in the + commit object). This is sometimes useful when you are + interested only in the recent history of a project even + though the real history recorded in the upstream is + much larger. A shallow repository is created by giving + `--depth` option to gitlink:git-clone[1], and its + history can be later deepened with gitlink:git-fetch[1]. + +symref:: + Symbolic reference: instead of containing the SHA1 id itself, it + is of the format 'ref: refs/some/thing' and when referenced, it + recursively dereferences to this reference. 'HEAD' is a prime + example of a symref. Symbolic references are manipulated with + the gitlink:git-symbolic-ref[1] command. + +topic branch:: + A regular git branch that is used by a developer to + identify a conceptual line of development. Since branches + are very easy and inexpensive, it is often desirable to + have several small branches that each contain very well + defined concepts or small incremental yet related changes. + +tracking branch:: + A regular git branch that is used to follow changes from + another repository. A tracking branch should not contain + direct modifications or have local commits made to it. + A tracking branch can usually be identified as the + right-hand-side ref in a Pull: refspec. + +tree object:: + An object containing a list of file names and modes along with refs + to the associated blob and/or tree objects. A tree is equivalent + to a directory. + +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). + +tree-ish:: + A ref pointing to either a commit object, a tree object, or a + tag object pointing to a tag or commit or tree object. + +tag object:: + An object containing a ref pointing to another object, which can + contain a message just like a commit object. It can also + contain a (PGP) signature, in which case it is called a "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). + A tag is most typically used to mark a particular point in the + commit ancestry chain. + +unmerged index:: + An index which contains unmerged index entries. + +unreachable object:: + An object which is not reachable from a branch, tag, or any + other reference. + +working tree:: + The set of files and directories currently being worked on, + i.e. you can work in your working tree without using git at all. + |