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https://github.com/git/git
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![Jonathan Nieder](/assets/img/avatar_default.png)
It is not necessarily obvious to a git novice what it means for a filesystem tree to be equal to the HEAD. Spell it out. Signed-off-by: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
462 lines
20 KiB
Plaintext
462 lines
20 KiB
Plaintext
[[def_alternate_object_database]]alternate object database::
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Via the alternates mechanism, a <<def_repository,repository>>
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can inherit part of its <<def_object_database,object database>>
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from another object database, which is called "alternate".
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[[def_bare_repository]]bare repository::
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A bare repository is normally an appropriately
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named <<def_directory,directory>> with a `.git` suffix that does not
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have a locally checked-out copy of any of the files under
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revision control. That is, all of the `git`
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administrative and control files that would normally be present in the
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hidden `.git` sub-directory are directly present in the
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`repository.git` directory instead,
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and no other files are present and checked out. Usually publishers of
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public repositories make bare repositories available.
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[[def_blob_object]]blob object::
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Untyped <<def_object,object>>, e.g. the contents of a file.
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[[def_branch]]branch::
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A "branch" is an active line of development. The most recent
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<<def_commit,commit>> on a branch is referred to as the tip of
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that branch. The tip of the branch is referenced by a branch
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<<def_head,head>>, which moves forward as additional development
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is done on the branch. A single git
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<<def_repository,repository>> can track an arbitrary number of
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branches, but your <<def_working_tree,working tree>> is
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associated with just one of them (the "current" or "checked out"
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branch), and <<def_HEAD,HEAD>> points to that branch.
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[[def_cache]]cache::
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Obsolete for: <<def_index,index>>.
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[[def_chain]]chain::
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A list of objects, where each <<def_object,object>> in the list contains
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a reference to its successor (for example, the successor of a
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<<def_commit,commit>> could be one of its <<def_parent,parents>>).
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[[def_changeset]]changeset::
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BitKeeper/cvsps speak for "<<def_commit,commit>>". Since git does not
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store changes, but states, it really does not make sense to use the term
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"changesets" with git.
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[[def_checkout]]checkout::
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The action of updating all or part of the
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<<def_working_tree,working tree>> with a <<def_tree_object,tree object>>
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or <<def_blob_object,blob>> from the
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<<def_object_database,object database>>, and updating the
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<<def_index,index>> and <<def_HEAD,HEAD>> if the whole working tree has
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been pointed at a new <<def_branch,branch>>.
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[[def_cherry-picking]]cherry-picking::
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In <<def_SCM,SCM>> jargon, "cherry pick" means to choose a subset of
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changes out of a series of changes (typically commits) and record them
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as a new series of changes on top of a different codebase. In GIT, this is
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performed by the "git cherry-pick" command to extract the change introduced
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by an existing <<def_commit,commit>> and to record it based on the tip
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of the current <<def_branch,branch>> as a new commit.
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[[def_clean]]clean::
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A <<def_working_tree,working tree>> is clean, if it
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corresponds to the <<def_revision,revision>> referenced by the current
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<<def_head,head>>. Also see "<<def_dirty,dirty>>".
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[[def_commit]]commit::
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As a noun: A single point in the
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git history; the entire history of a project is represented as a
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set of interrelated commits. The word "commit" is often
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used by git in the same places other revision control systems
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use the words "revision" or "version". Also used as a short
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hand for <<def_commit_object,commit object>>.
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+
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As a verb: The action of storing a new snapshot of the project's
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state in the git history, by creating a new commit representing the current
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state of the <<def_index,index>> and advancing <<def_HEAD,HEAD>>
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to point at the new commit.
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[[def_commit_object]]commit object::
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An <<def_object,object>> which contains the information about a
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particular <<def_revision,revision>>, such as <<def_parent,parents>>, committer,
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author, date and the <<def_tree_object,tree object>> which corresponds
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to the top <<def_directory,directory>> of the stored
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revision.
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[[def_core_git]]core git::
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Fundamental data structures and utilities of git. Exposes only limited
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source code management tools.
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[[def_DAG]]DAG::
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Directed acyclic graph. The <<def_commit_object,commit objects>> form a
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directed acyclic graph, because they have parents (directed), and the
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graph of commit objects is acyclic (there is no <<def_chain,chain>>
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which begins and ends with the same <<def_object,object>>).
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[[def_dangling_object]]dangling object::
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An <<def_unreachable_object,unreachable object>> which is not
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<<def_reachable,reachable>> even from other unreachable objects; a
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dangling object has no references to it from any
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reference or <<def_object,object>> in the <<def_repository,repository>>.
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[[def_detached_HEAD]]detached HEAD::
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Normally the <<def_HEAD,HEAD>> stores the name of a
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<<def_branch,branch>>. However, git also allows you to <<def_checkout,check out>>
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an arbitrary <<def_commit,commit>> that isn't necessarily the tip of any
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particular branch. In this case HEAD is said to be "detached".
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[[def_dircache]]dircache::
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You are *waaaaay* behind. See <<def_index,index>>.
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[[def_directory]]directory::
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The list you get with "ls" :-)
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[[def_dirty]]dirty::
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A <<def_working_tree,working tree>> is said to be "dirty" if
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it contains modifications which have not been <<def_commit,committed>> to the current
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<<def_branch,branch>>.
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[[def_ent]]ent::
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Favorite synonym to "<<def_tree-ish,tree-ish>>" by some total geeks. See
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`http://en.wikipedia.org/wiki/Ent_(Middle-earth)` for an in-depth
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explanation. Avoid this term, not to confuse people.
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[[def_evil_merge]]evil merge::
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An evil merge is a <<def_merge,merge>> that introduces changes that
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do not appear in any <<def_parent,parent>>.
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[[def_fast_forward]]fast forward::
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A fast-forward is a special type of <<def_merge,merge>> where you have a
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<<def_revision,revision>> and you are "merging" another
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<<def_branch,branch>>'s changes that happen to be a descendant of what
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you have. In such these cases, you do not make a new <<def_merge,merge>>
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<<def_commit,commit>> but instead just update to his
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revision. This will happen frequently on a
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<<def_tracking_branch,tracking branch>> of a remote
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<<def_repository,repository>>.
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[[def_fetch]]fetch::
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Fetching a <<def_branch,branch>> means to get the
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branch's <<def_head_ref,head ref>> from a remote
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<<def_repository,repository>>, to find out which objects are
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missing from the local <<def_object_database,object database>>,
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and to get them, too. See also linkgit:git-fetch[1].
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[[def_file_system]]file system::
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Linus Torvalds originally designed git to be a user space file system,
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i.e. the infrastructure to hold files and directories. That ensured the
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efficiency and speed of git.
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[[def_git_archive]]git archive::
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Synonym for <<def_repository,repository>> (for arch people).
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[[def_grafts]]grafts::
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Grafts enables two otherwise different lines of development to be joined
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together by recording fake ancestry information for commits. This way
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you can make git pretend the set of <<def_parent,parents>> a <<def_commit,commit>> has
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is different from what was recorded when the commit was
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created. Configured via the `.git/info/grafts` file.
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[[def_hash]]hash::
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In git's context, synonym to <<def_object_name,object name>>.
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[[def_head]]head::
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A <<def_ref,named reference>> to the <<def_commit,commit>> at the tip of a
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<<def_branch,branch>>. Heads are stored in
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`$GIT_DIR/refs/heads/`, except when using packed refs. (See
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linkgit:git-pack-refs[1].)
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[[def_HEAD]]HEAD::
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The current <<def_branch,branch>>. In more detail: Your <<def_working_tree,
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working tree>> is normally derived from the state of the tree
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referred to by HEAD. HEAD is a reference to one of the
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<<def_head,heads>> in your repository, except when using a
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<<def_detached_HEAD,detached HEAD>>, in which case it may
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reference an arbitrary commit.
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[[def_head_ref]]head ref::
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A synonym for <<def_head,head>>.
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[[def_hook]]hook::
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During the normal execution of several git commands, call-outs are made
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to optional scripts that allow a developer to add functionality or
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checking. Typically, the hooks allow for a command to be pre-verified
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and potentially aborted, and allow for a post-notification after the
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operation is done. The hook scripts are found in the
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`$GIT_DIR/hooks/` directory, and are enabled by simply
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removing the `.sample` suffix from the filename. In earlier versions
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of git you had to make them executable.
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[[def_index]]index::
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A collection of files with stat information, whose contents are stored
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as objects. The index is a stored version of your
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<<def_working_tree,working tree>>. Truth be told, it can also contain a second, and even
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a third version of a working tree, which are used
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when <<def_merge,merging>>.
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[[def_index_entry]]index entry::
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The information regarding a particular file, stored in the
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<<def_index,index>>. An index entry can be unmerged, if a
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<<def_merge,merge>> was started, but not yet finished (i.e. if
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the index contains multiple versions of that file).
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[[def_master]]master::
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The default development <<def_branch,branch>>. Whenever you
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create a git <<def_repository,repository>>, a branch named
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"master" is created, and becomes the active branch. In most
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cases, this contains the local development, though that is
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purely by convention and is not required.
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[[def_merge]]merge::
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As a verb: To bring the contents of another
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<<def_branch,branch>> (possibly from an external
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<<def_repository,repository>>) into the current branch. In the
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case where the merged-in branch is from a different repository,
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this is done by first <<def_fetch,fetching>> the remote branch
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and then merging the result into the current branch. This
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combination of fetch and merge operations is called a
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<<def_pull,pull>>. Merging is performed by an automatic process
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that identifies changes made since the branches diverged, and
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then applies all those changes together. In cases where changes
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conflict, manual intervention may be required to complete the
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merge.
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+
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As a noun: unless it is a <<def_fast_forward,fast forward>>, a
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successful merge results in the creation of a new <<def_commit,commit>>
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representing the result of the merge, and having as
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<<def_parent,parents>> the tips of the merged <<def_branch,branches>>.
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This commit is referred to as a "merge commit", or sometimes just a
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"merge".
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[[def_object]]object::
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The unit of storage in git. It is uniquely identified by the
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<<def_SHA1,SHA1>> of its contents. Consequently, an
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object can not be changed.
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[[def_object_database]]object database::
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Stores a set of "objects", and an individual <<def_object,object>> is
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identified by its <<def_object_name,object name>>. The objects usually
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live in `$GIT_DIR/objects/`.
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[[def_object_identifier]]object identifier::
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Synonym for <<def_object_name,object name>>.
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[[def_object_name]]object name::
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The unique identifier of an <<def_object,object>>. The <<def_hash,hash>>
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of the object's contents using the Secure Hash Algorithm
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1 and usually represented by the 40 character hexadecimal encoding of
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the <<def_hash,hash>> of the object.
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[[def_object_type]]object type::
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One of the identifiers "<<def_commit_object,commit>>",
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"<<def_tree_object,tree>>", "<<def_tag_object,tag>>" or
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"<<def_blob_object,blob>>" describing the type of an
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<<def_object,object>>.
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[[def_octopus]]octopus::
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To <<def_merge,merge>> more than two <<def_branch,branches>>. Also denotes an
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intelligent predator.
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[[def_origin]]origin::
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The default upstream <<def_repository,repository>>. Most projects have
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at least one upstream project which they track. By default
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'origin' is used for that purpose. New upstream updates
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will be fetched into remote <<def_tracking_branch,tracking branches>> named
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origin/name-of-upstream-branch, which you can see using
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`git branch -r`.
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[[def_pack]]pack::
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A set of objects which have been compressed into one file (to save space
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or to transmit them efficiently).
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[[def_pack_index]]pack index::
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The list of identifiers, and other information, of the objects in a
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<<def_pack,pack>>, to assist in efficiently accessing the contents of a
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pack.
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[[def_parent]]parent::
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A <<def_commit_object,commit object>> contains a (possibly empty) list
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of the logical predecessor(s) in the line of development, i.e. its
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parents.
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[[def_pickaxe]]pickaxe::
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The term <<def_pickaxe,pickaxe>> refers to an option to the diffcore
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routines that help select changes that add or delete a given text
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string. With the `--pickaxe-all` option, it can be used to view the full
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<<def_changeset,changeset>> that introduced or removed, say, a
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particular line of text. See linkgit:git-diff[1].
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[[def_plumbing]]plumbing::
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Cute name for <<def_core_git,core git>>.
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[[def_porcelain]]porcelain::
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Cute name for programs and program suites depending on
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<<def_core_git,core git>>, presenting a high level access to
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core git. Porcelains expose more of a <<def_SCM,SCM>>
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interface than the <<def_plumbing,plumbing>>.
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[[def_pull]]pull::
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Pulling a <<def_branch,branch>> means to <<def_fetch,fetch>> it and
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<<def_merge,merge>> it. See also linkgit:git-pull[1].
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[[def_push]]push::
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Pushing a <<def_branch,branch>> means to get the branch's
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<<def_head_ref,head ref>> from a remote <<def_repository,repository>>,
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find out if it is a direct ancestor to the branch's local
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head ref, and in that case, putting all
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objects, which are <<def_reachable,reachable>> from the local
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head ref, and which are missing from the remote
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repository, into the remote
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<<def_object_database,object database>>, and updating the remote
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head ref. If the remote <<def_head,head>> is not an
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ancestor to the local head, the push fails.
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[[def_reachable]]reachable::
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All of the ancestors of a given <<def_commit,commit>> are said to be
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"reachable" from that commit. More
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generally, one <<def_object,object>> is reachable from
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another if we can reach the one from the other by a <<def_chain,chain>>
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that follows <<def_tag,tags>> to whatever they tag,
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<<def_commit_object,commits>> to their parents or trees, and
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<<def_tree_object,trees>> to the trees or <<def_blob_object,blobs>>
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that they contain.
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[[def_rebase]]rebase::
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To reapply a series of changes from a <<def_branch,branch>> to a
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different base, and reset the <<def_head,head>> of that branch
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to the result.
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[[def_ref]]ref::
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A 40-byte hex representation of a <<def_SHA1,SHA1>> or a name that
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denotes a particular <<def_object,object>>. These may be stored in
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`$GIT_DIR/refs/`.
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[[def_reflog]]reflog::
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A reflog shows the local "history" of a ref. In other words,
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it can tell you what the 3rd last revision in _this_ repository
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was, and what was the current state in _this_ repository,
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yesterday 9:14pm. See linkgit:git-reflog[1] for details.
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[[def_refspec]]refspec::
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A "refspec" is used by <<def_fetch,fetch>> and
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<<def_push,push>> to describe the mapping between remote
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<<def_ref,ref>> and local ref. They are combined with a colon in
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the format <src>:<dst>, preceded by an optional plus sign, +.
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For example: `git fetch $URL
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refs/heads/master:refs/heads/origin` means "grab the master
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<<def_branch,branch>> <<def_head,head>> from the $URL and store
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it as my origin branch head". And `git push
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$URL refs/heads/master:refs/heads/to-upstream` means "publish my
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master branch head as to-upstream branch at $URL". See also
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linkgit:git-push[1].
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[[def_repository]]repository::
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A collection of <<def_ref,refs>> together with an
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<<def_object_database,object database>> containing all objects
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which are <<def_reachable,reachable>> from the refs, possibly
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accompanied by meta data from one or more <<def_porcelain,porcelains>>. A
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repository can share an object database with other repositories
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via <<def_alternate_object_database,alternates mechanism>>.
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[[def_resolve]]resolve::
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The action of fixing up manually what a failed automatic
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<<def_merge,merge>> left behind.
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[[def_revision]]revision::
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A particular state of files and directories which was stored in the
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<<def_object_database,object database>>. It is referenced by a
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<<def_commit_object,commit object>>.
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[[def_rewind]]rewind::
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To throw away part of the development, i.e. to assign the
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<<def_head,head>> to an earlier <<def_revision,revision>>.
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[[def_SCM]]SCM::
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Source code management (tool).
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[[def_SHA1]]SHA1::
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Synonym for <<def_object_name,object name>>.
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[[def_shallow_repository]]shallow repository::
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A shallow <<def_repository,repository>> has an incomplete
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history some of whose <<def_commit,commits>> have <<def_parent,parents>> cauterized away (in other
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words, git is told to pretend that these commits do not have the
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parents, even though they are recorded in the <<def_commit_object,commit
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object>>). This is sometimes useful when you are interested only in the
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recent history of a project even though the real history recorded in the
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upstream is much larger. A shallow repository
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is created by giving the `--depth` option to linkgit:git-clone[1], and
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its history can be later deepened with linkgit:git-fetch[1].
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[[def_symref]]symref::
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Symbolic reference: instead of containing the <<def_SHA1,SHA1>>
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id itself, it is of the format 'ref: refs/some/thing' and when
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referenced, it recursively dereferences to this reference.
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'<<def_HEAD,HEAD>>' is a prime example of a symref. Symbolic
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references are manipulated with the linkgit:git-symbolic-ref[1]
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command.
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[[def_tag]]tag::
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A <<def_ref,ref>> pointing to a <<def_tag_object,tag>> or
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<<def_commit_object,commit object>>. In contrast to a <<def_head,head>>,
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a tag is not changed by a <<def_commit,commit>>. Tags (not
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<<def_tag_object,tag objects>>) are stored in `$GIT_DIR/refs/tags/`. A
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git tag has nothing to do with a Lisp tag (which would be
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called an <<def_object_type,object type>> in git's context). A
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tag is most typically used to mark a particular point in the
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commit ancestry <<def_chain,chain>>.
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[[def_tag_object]]tag object::
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An <<def_object,object>> containing a <<def_ref,ref>> pointing to
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another object, which can contain a message just like a
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<<def_commit_object,commit object>>. It can also contain a (PGP)
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signature, in which case it is called a "signed tag object".
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[[def_topic_branch]]topic branch::
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A regular git <<def_branch,branch>> that is used by a developer to
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identify a conceptual line of development. Since branches are very easy
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and inexpensive, it is often desirable to have several small branches
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that each contain very well defined concepts or small incremental yet
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related changes.
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[[def_tracking_branch]]tracking branch::
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A regular git <<def_branch,branch>> that is used to follow changes from
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another <<def_repository,repository>>. A tracking
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branch should not contain direct modifications or have local commits
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made to it. A tracking branch can usually be
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identified as the right-hand-side <<def_ref,ref>> in a Pull:
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<<def_refspec,refspec>>.
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[[def_tree]]tree::
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Either a <<def_working_tree,working tree>>, or a <<def_tree_object,tree
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object>> together with the dependent <<def_blob_object,blob>> and tree objects
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(i.e. a stored representation of a working tree).
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[[def_tree_object]]tree object::
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An <<def_object,object>> containing a list of file names and modes along
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with refs to the associated blob and/or tree objects. A
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<<def_tree,tree>> is equivalent to a <<def_directory,directory>>.
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[[def_tree-ish]]tree-ish::
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A <<def_ref,ref>> pointing to either a <<def_commit_object,commit
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object>>, a <<def_tree_object,tree object>>, or a <<def_tag_object,tag
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object>> pointing to a tag or commit or tree object.
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[[def_unmerged_index]]unmerged index::
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|
An <<def_index,index>> which contains unmerged
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<<def_index_entry,index entries>>.
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[[def_unreachable_object]]unreachable object::
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An <<def_object,object>> which is not <<def_reachable,reachable>> from a
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<<def_branch,branch>>, <<def_tag,tag>>, or any other reference.
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[[def_upstream_branch]]upstream branch::
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|
The default <<def_branch,branch>> that is merged into the branch in
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question (or the branch in question is rebased onto). It is configured
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|
via branch.<name>.remote and branch.<name>.merge. If the upstream branch
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of 'A' is 'origin/B' sometimes we say "'A' is tracking 'origin/B'".
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[[def_working_tree]]working tree::
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The tree of actual checked out files. The working tree normally
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contains the contents of the <<def_HEAD,HEAD>> commit's tree,
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plus any local changes that you have made but not yet committed.
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