gitglossary

GITGLOSSARY(7)                     Git Manual                     GITGLOSSARY(7)



NAME
       gitglossary - A Git Glossary

SYNOPSIS
       *

DESCRIPTION
       alternate object database
           Via the alternates mechanism, a repository can inherit part of its
           object database from another object database, which is called an
           "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 "branch" is an active line of development. The most recent commit
           on a branch is referred to as the tip of that branch. The tip of the
           branch is referenced by a branch head, which moves forward as
           additional development is done on the branch. A single Git repository
           can track an arbitrary number of branches, but your working tree is
           associated with just one of them (the "current" or "checked out"
           branch), and HEAD points to that branch.

       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 all or part of the working tree with a tree
           object or blob from the object database, and updating the index and
           HEAD if the whole working tree has been pointed at a new branch.

       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 a different codebase. In Git, this is
           performed by the "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 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 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 index and advancing HEAD to point at the new
           commit.

       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.

       commit-ish (also committish)
           A commit object or an object that can be recursively dereferenced to
           a commit object. The following are all commit-ishes: a commit object,
           a tag object that points to a commit object, a tag object that points
           to a tag object that points to a commit object, etc.

       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.

       detached HEAD
           Normally the HEAD stores the name of a 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 check out an arbitrary 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.

       directory
           The list you get with "ls" :-)

       dirty
           A working tree is said to be "dirty" if it contains modifications
           which have not been committed to the current branch.

       evil merge
           An evil merge is a merge that introduces changes that do not appear
           in any parent.

       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 a case, you do not make a new
           merge commit but instead just update to his revision. This will
           happen frequently on a remote-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. See also git-fetch(1).

       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).

       gitfile
           A plain file .git at the root of a working tree that points at the
           directory that is the real repository.

       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.

           Note that the grafts mechanism is outdated and can lead to problems
           transferring objects between repositories; see git-replace(1) for a
           more flexible and robust system to do the same thing.

       hash
           In Git’s context, synonym for object name.

       head
           A named reference to the commit at the tip of a branch. Heads are
           stored in a file in $GIT_DIR/refs/heads/ directory, except when using
           packed refs. (See git-pack-refs(1).)

       HEAD
           The current branch. In more detail: Your working tree is normally
           derived from the state of the tree referred to by HEAD. HEAD is a
           reference to one of the heads in your repository, except when using a
           detached HEAD, in which case it directly references an arbitrary
           commit.

       head ref
           A synonym for head.

       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.

       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 by convention and is not required.

       merge
           As a verb: To bring the contents of another branch (possibly from an
           external repository) into the current branch. In the case where the
           merged-in branch is from a different repository, this is done by
           first fetching the remote branch and then merging the result into the
           current branch. This combination of fetch and merge operations is
           called a 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 fast-forward, a successful merge results in
           the creation of a new commit representing the result of the merge,
           and having as parents the tips of the merged branches. This commit is
           referred to as a "merge commit", or sometimes just a "merge".

       object
           The unit of storage in Git. It is uniquely identified by the SHA-1 of
           its contents. Consequently, an object cannot 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 object name is usually
           represented by a 40 character hexadecimal string. Also colloquially
           called SHA-1.

       object type
           One of the identifiers "commit", "tree", "tag" or "blob" describing
           the type of an object.

       octopus
           To merge more than two branches.

       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.

       overlay
           Only update and add files to the working directory, but don’t delete
           them, similar to how cp -R would update the contents in the
           destination directory. This is the default mode in a checkout when
           checking out files from the index or a tree-ish. In contrast,
           no-overlay mode also deletes tracked files not present in the source,
           similar to rsync --delete.

       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.

       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
           "magic signature" consists of ASCII symbols that are neither
           alphanumeric, glob, regex special characters nor colon. The optional
           colon that terminates the "magic signature" can be omitted if the
           pattern begins with a character that does not belong to "magic
           signature" symbol set and is not a colon.

           In the long form, the leading colon : is followed by an 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.

           A pathspec with only a colon means "there is no pathspec". This form
           should not be combined with other pathspec.

           top
               The magic word top (magic signature: /) makes the pattern match
               from the root of the working tree, even when you are running the
               command from inside a subdirectory.

           literal
               Wildcards in the pattern such as * or ?  are treated as literal
               characters.

           icase
               Case insensitive match.

           glob
               Git treats the pattern as a shell glob suitable for consumption
               by fnmatch(3) with the FNM_PATHNAME flag: wildcards in the
               pattern will not match a / in the pathname. For example,
               "Documentation/*.html" matches "Documentation/git.html" but not
               "Documentation/ppc/ppc.html" or
               "tools/perf/Documentation/perf.html".

               Two consecutive asterisks ("**") in patterns matched against full
               pathname may have special meaning:

               •   A leading "**" followed by a slash means match in all
                   directories. For example, "**/foo" matches file or directory
                   "foo" anywhere, the same as pattern "foo". "**/foo/bar"
                   matches file or directory "bar" anywhere that is directly
                   under directory "foo".

               •   A trailing "/**" matches everything inside. For example,
                   "abc/**" matches all files inside directory "abc", relative
                   to the location of the .gitignore file, with infinite depth.

               •   A slash followed by two consecutive asterisks then a slash
                   matches zero or more directories. For example, "a/**/b"
                   matches "a/b", "a/x/b", "a/x/y/b" and so on.

               •   Other consecutive asterisks are considered invalid.

                   Glob magic is incompatible with literal magic.

           attr
               After attr: comes a space separated list of "attribute
               requirements", all of which must be met in order for the path to
               be considered a match; this is in addition to the usual non-magic
               pathspec pattern matching. See gitattributes(5).

               Each of the attribute requirements for the path takes one of
               these forms:

               •   "ATTR" requires that the attribute ATTR be set.

               •   "-ATTR" requires that the attribute ATTR be unset.

               •   "ATTR=VALUE" requires that the attribute ATTR be set to the
                   string VALUE.

               •   "!ATTR" requires that the attribute ATTR be unspecified.

                   Note that when matching against a tree object, attributes are
                   still obtained from working tree, not from the given tree
                   object.

           exclude
               After a path matches any non-exclude pathspec, it will be run
               through all exclude pathspecs (magic signature: !  or its synonym
               ^). If it matches, the path is ignored. When there is no
               non-exclude pathspec, the exclusion is applied to the result set
               as if invoked without any pathspec.

       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 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.

       per-worktree ref
           Refs that are per-worktree, rather than global. This is presently
           only HEAD and any refs that start with refs/bisect/, but might later
           include other unusual refs.

       pseudoref
           Pseudorefs are a class of files under $GIT_DIR which behave like refs
           for the purposes of rev-parse, but which are treated specially by
           git. Pseudorefs both have names that are all-caps, and always start
           with a line consisting of a SHA-1 followed by whitespace. So, HEAD is
           not a pseudoref, because it is sometimes a symbolic ref. They might
           optionally contain some additional data.  MERGE_HEAD and
           CHERRY_PICK_HEAD are examples. Unlike per-worktree refs, these files
           cannot be symbolic refs, and never have reflogs. They also cannot be
           updated through the normal ref update machinery. Instead, they are
           updated by directly writing to the files. However, they can be read
           as if they were refs, so git rev-parse MERGE_HEAD will work.

       pull
           Pulling a branch means to fetch it and merge it. See also git-
           pull(1).

       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, 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 reapply a series of changes from a branch to a different base, and
           reset the head of that branch to the result.

       ref
           A name that begins with refs/ (e.g.  refs/heads/master) that points
           to an object name or another ref (the latter is called a symbolic
           ref). For convenience, a ref can sometimes be abbreviated when used
           as an argument to a Git command; see gitrevisions(7) for details.
           Refs are stored in the repository.

           The ref namespace is hierarchical. Different subhierarchies are used
           for different purposes (e.g. the refs/heads/ hierarchy is used to
           represent local branches).

           There are a few special-purpose refs that do not begin with refs/.
           The most notable example is HEAD.

       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 git-
           reflog(1) for details.

       refspec
           A "refspec" is used by fetch and push to describe the mapping between
           remote ref and local ref.

       remote repository
           A repository which is used to track the same project but resides
           somewhere else. To communicate with remotes, see fetch or push.

       remote-tracking branch
           A ref that is used to follow changes from another repository. It
           typically looks like refs/remotes/foo/bar (indicating that it tracks
           a branch named bar in a remote named foo), and matches the
           right-hand-side of a configured fetch refspec. A remote-tracking
           branch should not contain direct modifications or have local commits
           made to it.

       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 via alternates mechanism.

       resolve
           The action of fixing up manually what a failed automatic merge left
           behind.

       revision
           Synonym for commit (the noun).

       rewind
           To throw away part of the development, i.e. to assign the head to an
           earlier revision.

       SCM
           Source code management (tool).

       SHA-1
           "Secure Hash Algorithm 1"; a cryptographic hash function. In the
           context of Git used as a synonym for object name.

       shallow clone
           Mostly a synonym to shallow repository but the phrase makes it more
           explicit that it was created by running git clone --depth=...
           command.

       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 the --depth option to git-clone(1),
           and its history can be later deepened with git-fetch(1).

       stash entry
           An object used to temporarily store the contents of a dirty working
           directory and the index for future reuse.

       submodule
           A repository that holds the history of a separate project inside
           another repository (the latter of which is called superproject).

       superproject
           A repository that references repositories of other projects in its
           working tree as submodules. The superproject knows about the names of
           (but does not hold copies of) commit objects of the contained
           submodules.

       symref
           Symbolic reference: instead of containing the SHA-1 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 git-
           symbolic-ref(1) command.

       tag
           A ref under refs/tags/ namespace that points to an object of an
           arbitrary type (typically a tag points to either a tag or a commit
           object). In contrast to a 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 object type in Git’s context). A tag is most typically used
           to mark a particular point in the commit ancestry chain.

       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".

       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.

       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 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-ish (also treeish)
           A tree object or an object that can be recursively dereferenced to a
           tree object. Dereferencing a commit object yields the tree object
           corresponding to the revision's top directory. The following are all
           tree-ishes: a commit-ish, a tree object, a tag object that points to
           a tree object, a tag object that points to a tag object that points
           to a tree object, etc.

       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.

       upstream branch
           The default 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".

       working tree
           The tree of actual checked out files. The working tree normally
           contains the contents of the HEAD commit’s tree, plus any local
           changes that you have made but not yet committed.

SEE ALSO
       gittutorial(7), gittutorial-2(7), gitcvs-migration(7), giteveryday(7),
       The Git User’s Manual[1]

GIT
       Part of the git(1) suite

NOTES
        1. The Git User’s Manual
           file:///usr/share/doc/git-doc/user-manual.html



Git 2.29.2                         10/30/2020                     GITGLOSSARY(7)