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============
[[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
- <<def_object_database,object database>>, which is called "alternate".
+ 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 <<def_bare_repository,bare repository>> is normally an appropriately
+ 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
- <<def_revision,revision>> control. That is, all of the `git`
+ 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,
Untyped <<def_object,object>>, e.g. the contents of a file.
[[def_branch]]branch::
- A non-cyclical graph of revisions, i.e. the complete history of a
- particular <<def_revision,revision>>, which is called the
- branch <<def_head,head>>. The heads
- are stored in `$GIT_DIR/refs/heads/`.
+ 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 parents).
+ <<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
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 <<def_commit,commit>> and to record it based on the tip
- of the current <<def_branch,branch>> as a new <<def_commit,commit>>.
+ of the current <<def_branch,branch>> as a new commit.
[[def_clean]]clean::
- A <<def_working_tree,working tree>> is <<def_clean,clean>>, if it
+ 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 verb: The action of storing the current state of the
- <<def_index,index>> in the <<def_object_database,object database>>. The
- result is a <<def_revision,revision>>. As a noun: Short hand for
- <<def_commit_object,commit object>>.
+ 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 parents, committer,
+ 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
- <<def_revision,revision>>.
+ revision.
[[def_core_git]]core git::
Fundamental data structures and utilities of git. Exposes only limited
[[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 <<def_commit,commit>> objects is acyclic (there is no
+ 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
- <<def_dangling_object,dangling object>> has no references to it from any
+ 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.
+ 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 <<def_dirty,dirty>> if
- it contains modifications which have not been committed to the current
+ 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::
`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
- <<def_revision,revision>>. This will happen frequently on a
+ 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
- <<def_branch,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.
+ 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 gitlink:git-fetch[1].
[[def_file_system]]file system::
Linus Torvalds originally designed git to be a user space file system,
[[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 <<def_commit,commit>> has
- is different from what was recorded when the <<def_commit,commit>> was
+ 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::
- The top of a <<def_branch,branch>>. It contains a <<def_ref,ref>> to the
- corresponding <<def_commit_object,commit object>>.
+ 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
+ gitlink: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 <<def_ref,ref>> pointing to a <<def_head,head>>. Often, this is
- abbreviated to "<<def_head,head>>". Head refs are stored in
- `$GIT_DIR/refs/heads/`.
+ A synonym for <<def_head,head>>.
[[def_hook]]hook::
During the normal execution of several git commands, call-outs are made
to optional scripts that allow a developer to add functionality or
checking. Typically, the hooks allow for a command to be pre-verified
and potentially aborted, and allow for a post-notification after the
- operation is done. The <<def_hook,hook>> scripts are found in the
- `$GIT_DIR/hooks/` <<def_directory,directory>>, and are enabled by simply
+ 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 <<def_index,index>> is a stored version of your working
- <<def_tree,tree>>. Truth be told, it can also contain a second, and even
- a third version of a <<def_working_tree,working tree>>, which are used
- when merging.
+ 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 <<def_index_entry,index entry>> can be unmerged,
- if a <<def_merge,merge>> was started, but not yet finished (i.e. if the
- <<def_index,index>> contains multiple versions of that file).
+ <<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 <<def_branch,branch>> named
- "<<def_master,master>>" is created, and becomes the active
- <<def_branch,branch>>. In most cases, this contains the local
- development, though that is purely conventional and not required.
+ 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::
- To <<def_merge,merge>> branches means to try to accumulate the changes
- since a common ancestor and apply them to the first
- <<def_branch,branch>>. An automatic <<def_merge,merge>> uses heuristics
- to accomplish that. Evidently, an automatic <<def_merge,merge>> can
- fail.
+ 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
- <<def_object,object>> can not be changed.
+ object can not be changed.
[[def_object_database]]object database::
Stores a set of "objects", and an individual <<def_object,object>> is
[[def_object_name]]object name::
The unique identifier of an <<def_object,object>>. The <<def_hash,hash>>
- of the <<def_object,object>>'s contents using the Secure Hash Algorithm
+ 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 <<def_object,object>> (possibly followed by
+ the <<def_hash,hash>> of the object (possibly followed by
a white space).
[[def_object_type]]object type::
describing the type of an <<def_object,object>>.
[[def_octopus]]octopus::
- To <<def_merge,merge>> more than two branches. Also denotes an
+ 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
- '<<def_origin,origin>>' is used for that purpose. New upstream updates
- will be fetched into remote tracking branches named
+ '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 <<def_branch,branch>> -r".
+ "`git branch -r`".
[[def_pack]]pack::
A set of objects which have been compressed into one file (to save space
[[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
- <<def_pack,pack>>.
+ pack.
[[def_parent]]parent::
A <<def_commit_object,commit object>> contains a (possibly empty) list
[[def_porcelain]]porcelain::
Cute name for programs and program suites depending on
<<def_core_git,core git>>, presenting a high level access to
- <<def_core_git,core git>>. Porcelains expose more of a <<def_SCM,SCM>>
+ 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.
+ <<def_merge,merge>> it. See also gitlink:git-pull[1].
[[def_push]]push::
- Pushing a <<def_branch,branch>> means to get the <<def_branch,branch>>'s
+ 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 an ancestor to the <<def_branch,branch>>'s local
- <<def_head_ref,head ref>> is a direct, and in that case, putting all
+ find out if it is an ancestor to the branch's local
+ head ref is a direct, and in that case, putting all
objects, which are <<def_reachable,reachable>> from the local
- <<def_head_ref,head ref>>, and which are missing from the remote
- <<def_repository,repository>>, into the remote
+ head ref, and which are missing from the remote
+ repository, into the remote
<<def_object_database,object database>>, and updating the remote
- <<def_head_ref,head ref>>. If the remote <<def_head,head>> is not an
- ancestor to the local <<def_head,head>>, the <<def_push,push>> fails.
+ 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
- <<def_reachable,reachable>> from that <<def_commit,commit>>. More
- generally, one <<def_object,object>> is <<def_reachable,reachable>> from
+ "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
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 gitlink:git-reflog[1] for details.
+
[[def_refspec]]refspec::
- A <<def_refspec,refspec>> is used by <<def_fetch,fetch>> and
- <<def_push,push>> to describe the mapping between remote <<def_ref,ref>>
- and local <<def_ref,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
- <<def_branch,branch>> <<def_head,head>>". And `git <<def_push,push>>
- $URL refs/heads/master:refs/heads/to-upstream` means
- "publish my master <<def_branch,branch>>
- <<def_head,head>> as to-upstream <<def_branch,branch>> at $URL". See
- also gitlink:git-push[1]
+ 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
+ gitlink:git-push[1]
[[def_repository]]repository::
- A collection of 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
- porcelains. A <<def_repository,repository>> can share an
- <<def_object_database,object database>> with other repositories.
+ 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
Synonym for <<def_object_name,object name>>.
[[def_shallow_repository]]shallow repository::
- A <<def_shallow_repository,shallow repository>> has an incomplete
- history some of whose commits have parents cauterized away (in other
+ 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 <<def_shallow_repository,shallow repository>>
+ upstream is much larger. A shallow repository
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 <<def_SHA1,SHA1>> 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 <<def_symref,symref>>. Symbolic references are
- manipulated with the gitlink:git-symbolic-ref[1] command.
+ 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 gitlink:git-symbolic-ref[1]
+ command.
[[def_tag]]tag::
- A <<def_ref,ref>> pointing to a <<def_tag,tag>> or
+ 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
- <<def_commit,commit>> ancestry <<def_chain,chain>>.
+ commit ancestry <<def_chain,chain>>.
[[def_tag_object]]tag object::
An <<def_object,object>> containing a <<def_ref,ref>> pointing to
- another <<def_object,object>>, which can contain a message just like a
+ 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 <<def_tag_object,tag
- object>>".
+ 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
[[def_tracking_branch]]tracking branch::
A regular git <<def_branch,branch>> that is used to follow changes from
- another <<def_repository,repository>>. A <<def_tracking_branch,tracking
- branch>> should not contain direct modifications or have local commits
- made to it. A <<def_tracking_branch,tracking branch>> can usually be
+ 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 blob and <<def_tree,tree>> objects
- (i.e. a stored representation of a <<def_working_tree,working 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
[[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 <<def_tag,tag>> or <<def_commit,commit>> or
- <<def_tree_object,tree object>>.
+ object>> pointing to a tag or commit or tree object.
[[def_unmerged_index]]unmerged index::
An <<def_index,index>> which contains unmerged
<<def_branch,branch>>, <<def_tag,tag>>, 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 <<def_working_tree,working tree>> without using git at all.
+ 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.