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diff --git a/Documentation/glossary.txt b/Documentation/glossary.txt new file mode 100644 index 0000000000..ab4caf4e26 --- /dev/null +++ b/Documentation/glossary.txt @@ -0,0 +1,454 @@ +GIT Glossary +============ + +[[def_alternate_object_database]]alternate object database:: + Via the alternates mechanism, a <<def_repository,repository>> + can inherit part of its <<def_object_database,object database>> + from another object database, which is called "alternate". + +[[def_bare_repository]]bare repository:: + A bare repository is normally an appropriately + named <<def_directory,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. + +[[def_blob_object]]blob object:: + Untyped <<def_object,object>>, e.g. the contents of a file. + +[[def_branch]]branch:: + A "branch" is an active line of development. The most recent + <<def_commit,commit>> on a branch is referred to as the tip of + that branch. The tip of the branch is referenced by a branch + <<def_head,head>>, which moves forward as additional development + is done on the branch. A single git + <<def_repository,repository>> can track an arbitrary number of + branches, but your <<def_working_tree,working tree>> is + associated with just one of them (the "current" or "checked out" + branch), and <<def_HEAD,HEAD>> points to that branch. + +[[def_cache]]cache:: + Obsolete for: <<def_index,index>>. + +[[def_chain]]chain:: + A list of objects, where each <<def_object,object>> in the list contains + a reference to its successor (for example, the successor of a + <<def_commit,commit>> could be one of its <<def_parent,parents>>). + +[[def_changeset]]changeset:: + BitKeeper/cvsps speak for "<<def_commit,commit>>". 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 <<def_working_tree,working tree>> to a + <<def_revision,revision>> which was stored in the + <<def_object_database,object database>>. + +[[def_cherry-picking]]cherry-picking:: + In <<def_SCM,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 a different codebase. In GIT, this is + performed by the "git cherry-pick" command to extract the change introduced + by an existing <<def_commit,commit>> and to record it based on the tip + of the current <<def_branch,branch>> as a new commit. + +[[def_clean]]clean:: + A <<def_working_tree,working tree>> is clean, if it + corresponds to the <<def_revision,revision>> referenced by the current + <<def_head,head>>. Also see "<<def_dirty,dirty>>". + +[[def_commit]]commit:: + As a noun: A single point in the + git history; the entire history of a project is represented as a + set of interrelated commits. The word "commit" is often + used by git in the same places other revision control systems + use the words "revision" or "version". Also used as a short + hand for <<def_commit_object,commit object>>. ++ +As a verb: The action of storing a new snapshot of the project's +state in the git history, by creating a new commit representing the current +state of the <<def_index,index>> and advancing <<def_HEAD,HEAD>> +to point at the new commit. + +[[def_commit_object]]commit object:: + An <<def_object,object>> which contains the information about a + particular <<def_revision,revision>>, such as <<def_parent,parents>>, committer, + author, date and the <<def_tree_object,tree object>> which corresponds + to the top <<def_directory,directory>> of the stored + revision. + +[[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 <<def_commit,commit>> objects form a + directed acyclic graph, because they have parents (directed), and the + graph of commit objects is acyclic (there is no + <<def_chain,chain>> which begins and ends with the same + <<def_object,object>>). + +[[def_dangling_object]]dangling object:: + An <<def_unreachable_object,unreachable object>> which is not + <<def_reachable,reachable>> even from other unreachable objects; a + dangling object has no references to it from any + reference or <<def_object,object>> in the <<def_repository,repository>>. + +[[def_detached_HEAD]]detached HEAD:: + Normally the <<def_HEAD,HEAD>> stores the name of a + <<def_branch,branch>>. However, git also allows you to <<def_checkout,check out>> + an arbitrary <<def_commit,commit>> that isn't necessarily the tip of any + particular branch. In this case HEAD is said to be "detached". + +[[def_dircache]]dircache:: + You are *waaaaay* behind. See <<def_index,index>>. + +[[def_directory]]directory:: + The list you get with "ls" :-) + +[[def_dirty]]dirty:: + A <<def_working_tree,working tree>> is said to be "dirty" if + it contains modifications which have not been <<def_commit,committed>> to the current + <<def_branch,branch>>. + +[[def_ent]]ent:: + Favorite synonym to "<<def_tree-ish,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. + +[[def_evil_merge]]evil merge:: + An evil merge is a <<def_merge,merge>> that introduces changes that + do not appear in any <<def_parent,parent>>. + +[[def_fast_forward]]fast forward:: + A fast-forward is a special type of <<def_merge,merge>> where you have a + <<def_revision,revision>> and you are "merging" another + <<def_branch,branch>>'s changes that happen to be a descendant of what + you have. In such these cases, you do not make a new <<def_merge,merge>> + <<def_commit,commit>> but instead just update to his + revision. This will happen frequently on a + <<def_tracking_branch,tracking branch>> of a remote + <<def_repository,repository>>. + +[[def_fetch]]fetch:: + Fetching a <<def_branch,branch>> means to get the + branch's <<def_head_ref,head ref>> from a remote + <<def_repository,repository>>, to find out which objects are + missing from the local <<def_object_database,object database>>, + and to get them, too. See also linkgit:git-fetch[1]. + +[[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 <<def_repository,repository>> (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 <<def_parent,parents>> a <<def_commit,commit>> has + is different from what was recorded when the commit was + created. Configured via the `.git/info/grafts` file. + +[[def_hash]]hash:: + In git's context, synonym to <<def_object_name,object name>>. + +[[def_head]]head:: + A <<def_ref,named reference>> to the <<def_commit,commit>> at the tip of a + <<def_branch,branch>>. Heads are stored in + `$GIT_DIR/refs/heads/`, except when using packed refs. (See + linkgit:git-pack-refs[1].) + +[[def_HEAD]]HEAD:: + The current <<def_branch,branch>>. In more detail: Your <<def_working_tree, + working tree>> is normally derived from the state of the tree + referred to by HEAD. HEAD is a reference to one of the + <<def_head,heads>> in your repository, except when using a + <<def_detached_HEAD,detached HEAD>>, in which case it may + reference an arbitrary commit. + +[[def_head_ref]]head ref:: + A synonym for <<def_head,head>>. + +[[def_hook]]hook:: + During the normal execution of several git commands, call-outs are made + to optional scripts that allow a developer to add functionality or + checking. Typically, the hooks allow for a command to be pre-verified + and potentially aborted, and allow for a post-notification after the + operation is done. The hook scripts are found in the + `$GIT_DIR/hooks/` directory, 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 index is a stored version of your + <<def_working_tree,working tree>>. Truth be told, it can also contain a second, and even + a third version of a working tree, which are used + when <<def_merge,merging>>. + +[[def_index_entry]]index entry:: + The information regarding a particular file, stored in the + <<def_index,index>>. An index entry can be unmerged, if a + <<def_merge,merge>> was started, but not yet finished (i.e. if + the index contains multiple versions of that file). + +[[def_master]]master:: + The default development <<def_branch,branch>>. Whenever you + create a git <<def_repository,repository>>, a branch named + "master" is created, and becomes the active branch. In most + cases, this contains the local development, though that is + purely by convention and is not required. + +[[def_merge]]merge:: + As a verb: To bring the contents of another + <<def_branch,branch>> (possibly from an external + <<def_repository,repository>>) into the current branch. In the + case where the merged-in branch is from a different repository, + this is done by first <<def_fetch,fetching>> the remote branch + and then merging the result into the current branch. This + combination of fetch and merge operations is called a + <<def_pull,pull>>. Merging is performed by an automatic process + that identifies changes made since the branches diverged, and + then applies all those changes together. In cases where changes + conflict, manual intervention may be required to complete the + merge. ++ +As a noun: unless it is a <<def_fast_forward,fast forward>>, a +successful merge results in the creation of a new <<def_commit,commit>> +representing the result of the merge, and having as +<<def_parent,parents>> the tips of the merged <<def_branch,branches>>. +This commit is referred to as a "merge commit", or sometimes just a +"merge". + +[[def_object]]object:: + The unit of storage in git. It is uniquely identified by the + <<def_SHA1,SHA1>> of its contents. Consequently, an + object can not be changed. + +[[def_object_database]]object database:: + Stores a set of "objects", and an individual <<def_object,object>> is + identified by its <<def_object_name,object name>>. The objects usually + live in `$GIT_DIR/objects/`. + +[[def_object_identifier]]object identifier:: + Synonym for <<def_object_name,object name>>. + +[[def_object_name]]object name:: + The unique identifier of an <<def_object,object>>. The <<def_hash,hash>> + of the object's contents using the Secure Hash Algorithm + 1 and usually represented by the 40 character hexadecimal encoding of + the <<def_hash,hash>> of the object. + +[[def_object_type]]object type:: + One of the identifiers + "<<def_commit,commit>>","<<def_tree,tree>>","<<def_tag,tag>>" or "<<def_blob_object,blob>>" + describing the type of an <<def_object,object>>. + +[[def_octopus]]octopus:: + To <<def_merge,merge>> more than two <<def_branch,branches>>. Also denotes an + intelligent predator. + +[[def_origin]]origin:: + The default upstream <<def_repository,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 <<def_tracking_branch,tracking branches>> named + origin/name-of-upstream-branch, which you can see using + "`git branch -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 + <<def_pack,pack>>, to assist in efficiently accessing the contents of a + pack. + +[[def_parent]]parent:: + A <<def_commit_object,commit object>> contains a (possibly empty) list + of the logical predecessor(s) in the line of development, i.e. its + parents. + +[[def_pickaxe]]pickaxe:: + The term <<def_pickaxe,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 + <<def_changeset,changeset>> that introduced or removed, say, a + particular line of text. See linkgit:git-diff[1]. + +[[def_plumbing]]plumbing:: + Cute name for <<def_core_git,core git>>. + +[[def_porcelain]]porcelain:: + Cute name for programs and program suites depending on + <<def_core_git,core git>>, presenting a high level access to + core git. Porcelains expose more of a <<def_SCM,SCM>> + interface than the <<def_plumbing,plumbing>>. + +[[def_pull]]pull:: + Pulling a <<def_branch,branch>> means to <<def_fetch,fetch>> it and + <<def_merge,merge>> it. See also linkgit:git-pull[1]. + +[[def_push]]push:: + Pushing a <<def_branch,branch>> means to get the branch's + <<def_head_ref,head ref>> from a remote <<def_repository,repository>>, + find out if it is a direct ancestor to the branch's local + head ref, and in that case, putting all + objects, which are <<def_reachable,reachable>> from the local + head ref, and which are missing from the remote + repository, into the remote + <<def_object_database,object database>>, and updating the remote + head ref. If the remote <<def_head,head>> is not an + ancestor to the local head, the push fails. + +[[def_reachable]]reachable:: + All of the ancestors of a given <<def_commit,commit>> are said to be + "reachable" from that commit. More + generally, one <<def_object,object>> is reachable from + another if we can reach the one from the other by a <<def_chain,chain>> + that follows <<def_tag,tags>> to whatever they tag, + <<def_commit_object,commits>> to their parents or trees, and + <<def_tree_object,trees>> to the trees or <<def_blob_object,blobs>> + that they contain. + +[[def_rebase]]rebase:: + To reapply a series of changes from a <<def_branch,branch>> to a + different base, and reset the <<def_head,head>> of that branch + to the result. + +[[def_ref]]ref:: + A 40-byte hex representation of a <<def_SHA1,SHA1>> or a name that + denotes a particular <<def_object,object>>. These may be stored in + `$GIT_DIR/refs/`. + +[[def_reflog]]reflog:: + A reflog shows the local "history" of a ref. In other words, + it can tell you what the 3rd last revision in _this_ repository + was, and what was the current state in _this_ repository, + yesterday 9:14pm. See linkgit:git-reflog[1] for details. + +[[def_refspec]]refspec:: + A "refspec" is used by <<def_fetch,fetch>> and + <<def_push,push>> to describe the mapping between remote + <<def_ref,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 + <<def_branch,branch>> <<def_head,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 + linkgit:git-push[1]. + +[[def_repository]]repository:: + A collection of <<def_ref,refs>> together with an + <<def_object_database,object database>> containing all objects + which are <<def_reachable,reachable>> from the refs, possibly + accompanied by meta data from one or more <<def_porcelain,porcelains>>. A + repository can share an object database with other repositories + via <<def_alternate_object_database,alternates mechanism>>. + +[[def_resolve]]resolve:: + The action of fixing up manually what a failed automatic + <<def_merge,merge>> left behind. + +[[def_revision]]revision:: + A particular state of files and directories which was stored in the + <<def_object_database,object database>>. It is referenced by a + <<def_commit_object,commit object>>. + +[[def_rewind]]rewind:: + To throw away part of the development, i.e. to assign the + <<def_head,head>> to an earlier <<def_revision,revision>>. + +[[def_SCM]]SCM:: + Source code management (tool). + +[[def_SHA1]]SHA1:: + Synonym for <<def_object_name,object name>>. + +[[def_shallow_repository]]shallow repository:: + A shallow <<def_repository,repository>> has an incomplete + history some of whose <<def_commit,commits>> have <<def_parent,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 <<def_commit_object,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 the `--depth` option to linkgit:git-clone[1], and + its history can be later deepened with linkgit:git-fetch[1]. + +[[def_symref]]symref:: + Symbolic reference: instead of containing the <<def_SHA1,SHA1>> + id itself, it is of the format 'ref: refs/some/thing' and when + referenced, it recursively dereferences to this reference. + '<<def_HEAD,HEAD>>' is a prime example of a symref. Symbolic + references are manipulated with the linkgit:git-symbolic-ref[1] + command. + +[[def_tag]]tag:: + A <<def_ref,ref>> pointing to a <<def_tag_object,tag>> or + <<def_commit_object,commit object>>. In contrast to a <<def_head,head>>, + a tag is not changed by a <<def_commit,commit>>. Tags (not + <<def_tag_object,tag objects>>) are stored in `$GIT_DIR/refs/tags/`. A + git tag has nothing to do with a Lisp tag (which would be + called an <<def_object_type,object type>> in git's context). A + tag is most typically used to mark a particular point in the + commit ancestry <<def_chain,chain>>. + +[[def_tag_object]]tag object:: + An <<def_object,object>> containing a <<def_ref,ref>> pointing to + another object, which can contain a message just like a + <<def_commit_object,commit object>>. It can also contain a (PGP) + signature, in which case it is called a "signed tag object". + +[[def_topic_branch]]topic branch:: + A regular git <<def_branch,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. + +[[def_tracking_branch]]tracking branch:: + A regular git <<def_branch,branch>> that is used to follow changes from + another <<def_repository,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 <<def_ref,ref>> in a Pull: + <<def_refspec,refspec>>. + +[[def_tree]]tree:: + Either a <<def_working_tree,working tree>>, or a <<def_tree_object,tree + object>> together with the dependent <<def_blob_object,blob>> and tree objects + (i.e. a stored representation of a working tree). + +[[def_tree_object]]tree object:: + An <<def_object,object>> containing a list of file names and modes along + with refs to the associated blob and/or tree objects. A + <<def_tree,tree>> is equivalent to a <<def_directory,directory>>. + +[[def_tree-ish]]tree-ish:: + A <<def_ref,ref>> pointing to either a <<def_commit_object,commit + object>>, a <<def_tree_object,tree object>>, or a <<def_tag_object,tag + object>> pointing to a tag or commit or tree object. + +[[def_unmerged_index]]unmerged index:: + An <<def_index,index>> which contains unmerged + <<def_index_entry,index entries>>. + +[[def_unreachable_object]]unreachable object:: + An <<def_object,object>> which is not <<def_reachable,reachable>> from a + <<def_branch,branch>>, <<def_tag,tag>>, or any other reference. + +[[def_working_tree]]working tree:: + The tree of actual checked out files. The working tree is + normally equal to the <<def_HEAD,HEAD>> plus any local changes + that you have made but not yet committed. |