Glossary
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Ancestor
Any changeset that can be reached by an unbroken chain of parent
changesets from a given changeset. More precisely, the ancestors
of a changeset can be defined by two properties: a parent of a
changeset is an ancestor, and a parent of an ancestor is an
ancestor. See also: 'Descendant'.
Bookmark
Bookmarks are pointers to certain commits that move when
committing. They are similar to tags in that it is possible to use
bookmark names in all places where Mercurial expects a changeset
ID, e.g., with :hg:`update`. Unlike tags, bookmarks move along
when you make a commit.
Bookmarks can be renamed, copied and deleted. Bookmarks are local,
unless they are explicitly pushed or pulled between repositories.
Pushing and pulling bookmarks allow you to collaborate with others
on a branch without creating a named branch.
Branch
(Noun) A child changeset that has been created from a parent that
is not a head. These are known as topological branches, see
'Branch, topological'. If a topological branch is named, it becomes
a named branch. If a topological branch is not named, it becomes
an anonymous branch. See 'Branch, anonymous' and 'Branch, named'.
Branches may be created when changes are pulled from or pushed to
a remote repository, since new heads may be created by these
operations. Note that the term branch can also be used informally
to describe a development process in which certain development is
done independently of other development. This is sometimes done
explicitly with a named branch, but it can also be done locally,
using bookmarks or clones and anonymous branches.
Example: "The experimental branch".
(Verb) The action of creating a child changeset which results in
its parent having more than one child.
Example: "I'm going to branch at X".
Branch, anonymous
Every time a new child changeset is created from a parent that is not
a head and the name of the branch is not changed, a new anonymous
branch is created.
Branch, closed
A named branch whose branch heads have all been closed.
Branch, default
The branch assigned to a changeset when no name has previously been
assigned.
Branch head
See 'Head, branch'.
Branch, inactive
If a named branch has no topological heads, it is considered to be
inactive. As an example, a feature branch becomes inactive when it
is merged into the default branch. The :hg:`branches` command
shows inactive branches by default, though they can be hidden with
:hg:`branches --active`.
NOTE: this concept is deprecated because it is too implicit.
Branches should now be explicitly closed using :hg:`commit
--close-branch` when they are no longer needed.
Branch, named
A collection of changesets which have the same branch name. By
default, children of a changeset in a named branch belong to the
same named branch. A child can be explicitly assigned to a
different branch. See :hg:`help branch`, :hg:`help branches` and
:hg:`commit --close-branch` for more information on managing
branches.
Named branches can be thought of as a kind of namespace, dividing
the collection of changesets that comprise the repository into a
collection of disjoint subsets. A named branch is not necessarily
a topological branch. If a new named branch is created from the
head of another named branch, or the default branch, but no
further changesets are added to that previous branch, then that
previous branch will be a branch in name only.
Branch tip
See 'Tip, branch'.
Branch, topological
Every time a new child changeset is created from a parent that is
not a head, a new topological branch is created. If a topological
branch is named, it becomes a named branch. If a topological
branch is not named, it becomes an anonymous branch of the
current, possibly default, branch.
Changelog
A record of the changesets in the order in which they were added
to the repository. This includes details such as changeset id,
author, commit message, date, and list of changed files.
Changeset
A snapshot of the state of the repository used to record a change.
Changeset, child
The converse of parent changeset: if P is a parent of C, then C is
a child of P. There is no limit to the number of children that a
changeset may have.
Changeset id
A SHA-1 hash that uniquely identifies a changeset. It may be
represented as either a "long" 40 hexadecimal digit string, or a
"short" 12 hexadecimal digit string.
Changeset, merge
A changeset with two parents. This occurs when a merge is
committed.
Changeset, parent
A revision upon which a child changeset is based. Specifically, a
parent changeset of a changeset C is a changeset whose node
immediately precedes C in the DAG. Changesets have at most two
parents.
Checkout
(Noun) The working directory being updated to a specific
revision. This use should probably be avoided where possible, as
changeset is much more appropriate than checkout in this context.
Example: "I'm using checkout X."
(Verb) Updating the working directory to a specific changeset. See
:hg:`help update`.
Example: "I'm going to check out changeset X."
Child changeset
See 'Changeset, child'.
Close changeset
See 'Head, closed branch'
Closed branch
See 'Branch, closed'.
Clone
(Noun) An entire or partial copy of a repository. The partial
clone must be in the form of a revision and its ancestors.
Example: "Is your clone up to date?".
(Verb) The process of creating a clone, using :hg:`clone`.
Example: "I'm going to clone the repository".
Closed branch head
See 'Head, closed branch'.
Commit
(Noun) A synonym for changeset.
Example: "Is the bug fixed in your recent commit?"
(Verb) The act of recording changes to a repository. When files
are committed in a working directory, Mercurial finds the
differences between the committed files and their parent
changeset, creating a new changeset in the repository.
Example: "You should commit those changes now."
Cset
A common abbreviation of the term changeset.
DAG
The repository of changesets of a distributed version control
system (DVCS) can be described as a directed acyclic graph (DAG),
consisting of nodes and edges, where nodes correspond to
changesets and edges imply a parent -> child relation. This graph
can be visualized by graphical tools such as :hg:`log --graph`. In
Mercurial, the DAG is limited by the requirement for children to
have at most two parents.
Default branch
See 'Branch, default'.
Descendant
Any changeset that can be reached by a chain of child changesets
from a given changeset. More precisely, the descendants of a
changeset can be defined by two properties: the child of a
changeset is a descendant, and the child of a descendant is a
descendant. See also: 'Ancestor'.
Diff
(Noun) The difference between the contents and attributes of files
in two changesets or a changeset and the current working
directory. The difference is usually represented in a standard
form called a "diff" or "patch". The "git diff" format is used
when the changes include copies, renames, or changes to file
attributes, none of which can be represented/handled by classic
"diff" and "patch".
Example: "Did you see my correction in the diff?"
(Verb) Diffing two changesets is the action of creating a diff or
patch.
Example: "If you diff with changeset X, you will see what I mean."
Directory, working
The working directory represents the state of the files tracked by
Mercurial, that will be recorded in the next commit. The working
directory initially corresponds to the snapshot at an existing
changeset, known as the parent of the working directory. See
'Parent, working directory'. The state may be modified by changes
to the files introduced manually or by a merge. The repository
metadata exists in the .hg directory inside the working directory.
Draft
Changesets in the draft phase have not been shared with publishing
repositories and may thus be safely changed by history-modifying
extensions. See :hg:`help phases`.
Graph
See DAG and :hg:`log --graph`.
Head
The term 'head' may be used to refer to both a branch head or a
repository head, depending on the context. See 'Head, branch' and
'Head, repository' for specific definitions.
Heads are where development generally takes place and are the
usual targets for update and merge operations.
Head, branch
A changeset with no descendants on the same named branch.
Head, closed branch
A changeset that marks a head as no longer interesting. The closed
head is no longer listed by :hg:`heads`. A branch is considered
closed when all its heads are closed and consequently is not
listed by :hg:`branches`.
Closed heads can be re-opened by committing new changeset as the
child of the changeset that marks a head as closed.
Head, repository
A topological head which has not been closed.
Head, topological
A changeset with no children in the repository.
History, immutable
Once committed, changesets cannot be altered. Extensions which
appear to change history actually create new changesets that
replace existing ones, and then destroy the old changesets. Doing
so in public repositories can result in old changesets being
reintroduced to the repository.
History, rewriting
The changesets in a repository are immutable. However, extensions
to Mercurial can be used to alter the repository, usually in such
a way as to preserve changeset contents.
Immutable history
See 'History, immutable'.
Merge changeset
See 'Changeset, merge'.
Manifest
Each changeset has a manifest, which is the list of files that are
tracked by the changeset.
Merge
Used to bring together divergent branches of work. When you update
to a changeset and then merge another changeset, you bring the
history of the latter changeset into your working directory. Once
conflicts are resolved (and marked), this merge may be committed
as a merge changeset, bringing two branches together in the DAG.
Named branch
See 'Branch, named'.
Null changeset
The empty changeset. It is the parent state of newly-initialized
repositories and repositories with no checked out revision. It is
thus the parent of root changesets and the effective ancestor when
merging unrelated changesets. Can be specified by the alias 'null'
or by the changeset ID '000000000000'.
Parent
See 'Changeset, parent'.
Parent changeset
See 'Changeset, parent'.
Parent, working directory
The working directory parent reflects a virtual revision which is
the child of the changeset (or two changesets with an uncommitted
merge) shown by :hg:`parents`. This is changed with
:hg:`update`. Other commands to see the working directory parent
are :hg:`summary` and :hg:`id`. Can be specified by the alias ".".
Patch
(Noun) The product of a diff operation.
Example: "I've sent you my patch."
(Verb) The process of using a patch file to transform one
changeset into another.
Example: "You will need to patch that revision."
Phase
A per-changeset state tracking how the changeset has been or
should be shared. See :hg:`help phases`.
Public
Changesets in the public phase have been shared with publishing
repositories and are therefore considered immutable. See :hg:`help
phases`.
Pull
An operation in which changesets in a remote repository which are
not in the local repository are brought into the local
repository. Note that this operation without special arguments
only updates the repository, it does not update the files in the
working directory. See :hg:`help pull`.
Push
An operation in which changesets in a local repository which are
not in a remote repository are sent to the remote repository. Note
that this operation only adds changesets which have been committed
locally to the remote repository. Uncommitted changes are not
sent. See :hg:`help push`.
Repository
The metadata describing all recorded states of a collection of
files. Each recorded state is represented by a changeset. A
repository is usually (but not always) found in the ``.hg``
subdirectory of a working directory. Any recorded state can be
recreated by "updating" a working directory to a specific
changeset.
Repository head
See 'Head, repository'.
Revision
A state of the repository at some point in time. Earlier revisions
can be updated to by using :hg:`update`. See also 'Revision
number'; See also 'Changeset'.
Revision number
This integer uniquely identifies a changeset in a specific
repository. It represents the order in which changesets were added
to a repository, starting with revision number 0. Note that the
revision number may be different in each clone of a repository. To
identify changesets uniquely between different clones, see
'Changeset id'.
Revlog
History storage mechanism used by Mercurial. It is a form of delta
encoding, with occasional full revision of data followed by delta
of each successive revision. It includes data and an index
pointing to the data.
Rewriting history
See 'History, rewriting'.
Root
A changeset that has only the null changeset as its parent. Most
repositories have only a single root changeset.
Secret
Changesets in the secret phase may not be shared via push, pull,
or clone. See :hg:`help phases`.
Tag
An alternative name given to a changeset. Tags can be used in all
places where Mercurial expects a changeset ID, e.g., with
:hg:`update`. The creation of a tag is stored in the history and
will thus automatically be shared with other using push and pull.
Tip
The changeset with the highest revision number. It is the changeset
most recently added in a repository.
Tip, branch
The head of a given branch with the highest revision number. When
a branch name is used as a revision identifier, it refers to the
branch tip. See also 'Branch, head'. Note that because revision
numbers may be different in different repository clones, the
branch tip may be different in different cloned repositories.
Update
(Noun) Another synonym of changeset.
Example: "I've pushed an update".
(Verb) This term is usually used to describe updating the state of
the working directory to that of a specific changeset. See
:hg:`help update`.
Example: "You should update".
Working directory
See 'Directory, working'.
Working directory parent
See 'Parent, working directory'.