Edit File: glossary-content.txt
[[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 all or part of the <<def_working_tree,working tree>> with a <<def_tree_object,tree object>> or <<def_blob_object,blob>> from the <<def_object_database,object database>>, and updating the <<def_index,index>> and <<def_HEAD,HEAD>> if the whole working tree has been pointed at a new <<def_branch,branch>>. [[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_object,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>>, and commands that operate on the history HEAD represents operate on the history leading to the tip of the branch the HEAD points at. 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. The HEAD in such a state is called "detached". + Note that commands that operate on the history of the current branch (e.g. `git commit` to build a new history on top of it) still work while the HEAD is detached. They update the HEAD to point at the tip of the updated history without affecting any branch. Commands that update or inquire information _about_ the current branch (e.g. `git branch --set-upstream-to` that sets what remote tracking branch the current branch integrates with) obviously do not work, as there is no (real) current branch to ask about in this state. [[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_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_remote_tracking_branch,remote-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_gitfile]]gitfile:: A plain file `.git` at the root of a working tree that points at the directory that is the real repository. [[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 for <<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 a file in `$GIT_DIR/refs/heads/` directory, except when using packed refs. (See linkgit:git-pack-refs[1].) [[def_HEAD]]HEAD:: The current <<def_branch,branch>>. In more detail: Your <<def_working_tree, working tree>> is normally derived from the state of the tree referred to by HEAD. HEAD is a reference to one of the <<def_head,heads>> in your repository, except when using a <<def_detached_HEAD,detached HEAD>>, in which case it directly references an arbitrary commit. [[def_head_ref]]head ref:: A synonym for <<def_head,head>>. [[def_hook]]hook:: During the normal execution of several Git commands, call-outs are made to optional scripts that allow a developer to add functionality or checking. Typically, the hooks allow for a command to be pre-verified and potentially aborted, and allow for a post-notification after the operation is done. The hook scripts are found in the `$GIT_DIR/hooks/` directory, and are enabled by simply removing the `.sample` suffix from the filename. In earlier versions of Git you had to make 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,SHA-1>> 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 object name is usually represented by a 40 character hexadecimal string. Also colloquially called <<def_SHA1,SHA-1>>. [[def_object_type]]object type:: One of the identifiers "<<def_commit_object,commit>>", "<<def_tree_object,tree>>", "<<def_tag_object,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>>. [[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_remote_tracking_branch,remote-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_pathspec]]pathspec:: Pattern used to limit paths in Git commands. + Pathspecs are used on the command line of "git ls-files", "git ls-tree", "git add", "git grep", "git diff", "git checkout", and many other commands to limit the scope of operations to some subset of the tree or worktree. See the documentation of each command for whether paths are relative to the current directory or toplevel. The pathspec syntax is as follows: + -- * any path matches itself * the pathspec up to the last slash represents a directory prefix. The scope of that pathspec is limited to that subtree. * the rest of the pathspec is a pattern for the remainder of the pathname. Paths relative to the directory prefix will be matched against that pattern using fnmatch(3); in particular, '*' and '?' _can_ match directory separators. -- + For example, Documentation/*.jpg will match all .jpg files in the Documentation subtree, including Documentation/chapter_1/figure_1.jpg. + A pathspec that begins with a colon `:` has special meaning. In the short form, the leading colon `:` is followed by zero or more "magic signature" letters (which optionally is terminated by another colon `:`), and the remainder is the pattern to match against the path. The optional colon that terminates the "magic signature" can be omitted if the pattern begins with a character that cannot be a "magic signature" and is not a colon. + In the long form, the leading colon `:` is followed by a open parenthesis `(`, a comma-separated list of zero or more "magic words", and a close parentheses `)`, and the remainder is the pattern to match against the path. + The "magic signature" consists of an ASCII symbol that is not alphanumeric. Currently only the slash `/` is recognized as a "magic signature": it makes the pattern match from the root of the working tree, even when you are running the command from inside a subdirectory. + A pathspec with only a colon means "there is no pathspec". This form should not be combined with other pathspec. [[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,SHA-1>> or a name that denotes a particular <<def_object,object>>. They may be stored in a file under `$GIT_DIR/refs/` directory, or in the `$GIT_DIR/packed-refs` file. [[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. [[def_remote_tracking_branch]]remote-tracking branch:: A regular Git <<def_branch,branch>> that is used to follow changes from another <<def_repository,repository>>. A remote-tracking branch should not contain direct modifications or have local commits made to it. A remote-tracking branch can usually be identified as the right-hand-side <<def_ref,ref>> in a Pull: <<def_refspec,refspec>>. [[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:: Synonym for <<def_commit,commit>> (the noun). [[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]]SHA-1:: "Secure Hash Algorithm 1"; a cryptographic hash function. In the context of Git used as a 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,SHA-1>> 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>> under `refs/tags/` namespace that points to an object of an arbitrary type (typically a tag points to either a <<def_tag_object,tag>> or a <<def_commit_object,commit object>>). In contrast to a <<def_head,head>>, a tag is not updated by the `commit` command. 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_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_upstream_branch]]upstream branch:: The default <<def_branch,branch>> that is merged into the branch in question (or the branch in question is rebased onto). It is configured via branch.<name>.remote and branch.<name>.merge. If the upstream branch of 'A' is 'origin/B' sometimes we say "'A' is tracking 'origin/B'". [[def_working_tree]]working tree:: The tree of actual checked out files. The working tree normally contains the contents of the <<def_HEAD,HEAD>> commit's tree, plus any local changes that you have made but not yet committed.