GIT Glossary ============ [[def_alternate_object_database]]alternate object database:: Via the alternates mechanism, a <> can inherit part of its <> from another <>, which is called "alternate". [[def_bare_repository]]bare repository:: A <> is normally an appropriately named <> with a `.git` suffix that does not have a locally checked-out copy of any of the files under <> 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. [[def_blob_object]]blob object:: Untyped <>, e.g. the contents of a file. [[def_branch]]branch:: A non-cyclical graph of revisions, i.e. the complete history of a particular <>, which is called the branch <>. The heads are stored in `$GIT_DIR/refs/heads/`. [[def_cache]]cache:: Obsolete for: <>. [[def_chain]]chain:: A list of objects, where each <> in the list contains a reference to its successor (for example, the successor of a <> could be one of its parents). [[def_changeset]]changeset:: BitKeeper/cvsps speak for "<>". Since git does not store changes, but states, it really does not make sense to use the term "changesets" with git. [[def_checkout]]checkout:: The action of updating the <> to a <> which was stored in the <>. [[def_cherry-picking]]cherry-picking:: In <> 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 <> and to record it based on the tip of the current <> as a new <>. [[def_clean]]clean:: A <> is <>, if it corresponds to the <> referenced by the current <>. Also see "<>". [[def_commit]]commit:: As a verb: The action of storing the current state of the <> in the <>. The result is a <>. As a noun: Short hand for <>. [[def_commit_object]]commit object:: An <> which contains the information about a particular <>, such as parents, committer, author, date and the <> which corresponds to the top <> of the stored <>. [[def_core_git]]core git:: Fundamental data structures and utilities of git. Exposes only limited source code management tools. [[def_DAG]]DAG:: Directed acyclic graph. The <> objects form a directed acyclic graph, because they have parents (directed), and the graph of <> objects is acyclic (there is no <> which begins and ends with the same <>). [[def_dangling_object]]dangling object:: An <> which is not <> even from other unreachable objects; a <> has no references to it from any reference or <> in the <>. [[def_dircache]]dircache:: You are *waaaaay* behind. [[def_directory]]directory:: The list you get with "ls" :-) [[def_dirty]]dirty:: A <> is said to be <> if it contains modifications which have not been committed to the current <>. [[def_ent]]ent:: Favorite synonym to "<>" 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. [[def_fast_forward]]fast forward:: A fast-forward is a special type of <> where you have a <> and you are "merging" another <>'s changes that happen to be a descendant of what you have. In such these cases, you do not make a new <> <> but instead just update to his <>. This will happen frequently on a <> of a remote <>. [[def_fetch]]fetch:: Fetching a <> means to get the <>'s <> from a remote <>, to find out which objects are missing from the local <>, and to get them, too. [[def_file_system]]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. [[def_git_archive]]git archive:: Synonym for <> (for arch people). [[def_grafts]]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 <> has is different from what was recorded when the <> was created. Configured via the `.git/info/grafts` file. [[def_hash]]hash:: In git's context, synonym to <>. [[def_head]]head:: The top of a <>. It contains a <> to the corresponding <>. [[def_head_ref]]head ref:: A <> pointing to a <>. Often, this is abbreviated to "<>". Head refs are stored in `$GIT_DIR/refs/heads/`. [[def_hook]]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 <> scripts are found in the `$GIT_DIR/hooks/` <>, and are enabled by simply making them executable. [[def_index]]index:: A collection of files with stat information, whose contents are stored as objects. The <> is a stored version of your working <>. Truth be told, it can also contain a second, and even a third version of a <>, which are used when merging. [[def_index_entry]]index entry:: The information regarding a particular file, stored in the <>. An <> can be unmerged, if a <> was started, but not yet finished (i.e. if the <> contains multiple versions of that file). [[def_master]]master:: The default development <>. Whenever you create a git <>, a <> named "<>" is created, and becomes the active <>. In most cases, this contains the local development, though that is purely conventional and not required. [[def_merge]]merge:: To <> branches means to try to accumulate the changes since a common ancestor and apply them to the first <>. An automatic <> uses heuristics to accomplish that. Evidently, an automatic <> can fail. [[def_object]]object:: The unit of storage in git. It is uniquely identified by the <> of its contents. Consequently, an <> can not be changed. [[def_object_database]]object database:: Stores a set of "objects", and an individual <> is identified by its <>. The objects usually live in `$GIT_DIR/objects/`. [[def_object_identifier]]object identifier:: Synonym for <>. [[def_object_name]]object name:: The unique identifier of an <>. The <> of the <>'s contents using the Secure Hash Algorithm 1 and usually represented by the 40 character hexadecimal encoding of the <> of the <> (possibly followed by a white space). [[def_object_type]]object type:: One of the identifiers "<>","<>","<>" or "<>" describing the type of an <>. [[def_octopus]]octopus:: To <> more than two branches. Also denotes an intelligent predator. [[def_origin]]origin:: The default upstream <>. Most projects have at least one upstream project which they track. By default '<>' 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 <> -r". [[def_pack]]pack:: A set of objects which have been compressed into one file (to save space or to transmit them efficiently). [[def_pack_index]]pack index:: The list of identifiers, and other information, of the objects in a <>, to assist in efficiently accessing the contents of a <>. [[def_parent]]parent:: A <> contains a (possibly empty) list of the logical predecessor(s) in the line of development, i.e. its parents. [[def_pickaxe]]pickaxe:: The term <> 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 <> that introduced or removed, say, a particular line of text. See gitlink:git-diff[1]. [[def_plumbing]]plumbing:: Cute name for <>. [[def_porcelain]]porcelain:: Cute name for programs and program suites depending on <>, presenting a high level access to <>. Porcelains expose more of a <> interface than the <>. [[def_pull]]pull:: Pulling a <> means to <> it and <> it. [[def_push]]push:: Pushing a <> means to get the <>'s <> from a remote <>, find out if it is an ancestor to the <>'s local <> is a direct, and in that case, putting all objects, which are <> from the local <>, and which are missing from the remote <>, into the remote <>, and updating the remote <>. If the remote <> is not an ancestor to the local <>, the <> fails. [[def_reachable]]reachable:: All of the ancestors of a given <> are said to be <> from that <>. More generally, one <> is <> from another if we can reach the one from the other by a <> that follows <> to whatever they tag, <> to their parents or trees, and <> to the trees or <> that they contain. [[def_rebase]]rebase:: To reapply a series of changes from a <> to a different base, and reset the <> of that branch to the result. [[def_ref]]ref:: A 40-byte hex representation of a <> or a name that denotes a particular <>. These may be stored in `$GIT_DIR/refs/`. [[def_refspec]]refspec:: A <> is used by <> and <> to describe the mapping between remote <> and local <>. They are combined with a colon in the format :, preceded by an optional plus sign, +. For example: `git fetch $URL refs/heads/master:refs/heads/origin` means "grab the master <> <> from the $URL and store it as my origin <> <>". And `git <> $URL refs/heads/master:refs/heads/to-upstream` means "publish my master <> <> as to-upstream <> at $URL". See also gitlink:git-push[1] [[def_repository]]repository:: A collection of refs together with an <> containing all objects which are <> from the refs, possibly accompanied by meta data from one or more porcelains. A <> can share an <> with other repositories. [[def_resolve]]resolve:: The action of fixing up manually what a failed automatic <> left behind. [[def_revision]]revision:: A particular state of files and directories which was stored in the <>. It is referenced by a <>. [[def_rewind]]rewind:: To throw away part of the development, i.e. to assign the <> to an earlier <>. [[def_SCM]]SCM:: Source code management (tool). [[def_SHA1]]SHA1:: Synonym for <>. [[def_shallow_repository]]shallow repository:: A <> has an incomplete history some of whose commits have parents cauterized away (in other words, git is told to pretend that these commits do not have the parents, even though they are recorded in the <>). This is sometimes useful when you are interested only in the recent history of a project even though the real history recorded in the upstream is much larger. A <> is created by giving the `--depth` option to gitlink:git-clone[1], and its history can be later deepened with gitlink:git-fetch[1]. [[def_symref]]symref:: Symbolic reference: instead of containing the <> id itself, it is of the format 'ref: refs/some/thing' and when referenced, it recursively dereferences to this reference. 'HEAD' is a prime example of a <>. Symbolic references are manipulated with the gitlink:git-symbolic-ref[1] command. [[def_tag]]tag:: A <> pointing to a <> or <>. In contrast to a <>, a tag is not changed by a <>. Tags (not <>) are stored in `$GIT_DIR/refs/tags/`. A git tag has nothing to do with a Lisp tag (which would be called an <> in git's context). A tag is most typically used to mark a particular point in the <> ancestry <>. [[def_tag_object]]tag object:: An <> containing a <> pointing to another <>, which can contain a message just like a <>. It can also contain a (PGP) signature, in which case it is called a "signed <>". [[def_topic_branch]]topic branch:: A regular git <> 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. [[def_tracking_branch]]tracking branch:: A regular git <> that is used to follow changes from another <>. A <> should not contain direct modifications or have local commits made to it. A <> can usually be identified as the right-hand-side <> in a Pull: <>. [[def_tree]]tree:: Either a <>, or a <> together with the dependent blob and <> objects (i.e. a stored representation of a <>). [[def_tree_object]]tree object:: An <> containing a list of file names and modes along with refs to the associated blob and/or tree objects. A <> is equivalent to a <>. [[def_tree-ish]]tree-ish:: A <> pointing to either a <>, a <>, or a <> pointing to a <> or <> or <>. [[def_unmerged_index]]unmerged index:: An <> which contains unmerged <>. [[def_unreachable_object]]unreachable object:: An <> which is not <> from a <>, <>, or any other reference. [[def_working_tree]]working tree:: The set of files and directories currently being worked on, i.e. you can work in your <> without using git at all.