simplify-merges: never remove all TREESAME parents

[thirdparty/git.git] / Documentation / rev-list-options.txt

Commit Limiting
~~~~~~~~~~~~~~~

Besides specifying a range of commits that should be listed using the
special notations explained in the description, additional commit
limiting may be applied.

Using more options generally further limits the output (e.g.
`--since=<date1>` limits to commits newer than `<date1>`, and using it
with `--grep=<pattern>` further limits to commits whose log message
has a line that matches `<pattern>`), unless otherwise noted.

Note that these are applied before commit
ordering and formatting options, such as `--reverse`.

--

-<number>::
-n <number>::
--max-count=<number>::

	Limit the number of commits to output.

--skip=<number>::

	Skip 'number' commits before starting to show the commit output.

--since=<date>::
--after=<date>::

	Show commits more recent than a specific date.

--until=<date>::
--before=<date>::

	Show commits older than a specific date.

ifdef::git-rev-list[]
--max-age=<timestamp>::
--min-age=<timestamp>::

	Limit the commits output to specified time range.
endif::git-rev-list[]

--author=<pattern>::
--committer=<pattern>::

	Limit the commits output to ones with author/committer
	header lines that match the specified pattern (regular
	expression).  With more than one `--author=<pattern>`,
	commits whose author matches any of the given patterns are
	chosen (similarly for multiple `--committer=<pattern>`).

--grep-reflog=<pattern>::

	Limit the commits output to ones with reflog entries that
	match the specified pattern (regular expression). With
	more than one `--grep-reflog`, commits whose reflog message
	matches any of the given patterns are chosen.  It is an
	error to use this option unless `--walk-reflogs` is in use.

--grep=<pattern>::

	Limit the commits output to ones with log message that
	matches the specified pattern (regular expression).  With
	more than one `--grep=<pattern>`, commits whose message
	matches any of the given patterns are chosen (but see
	`--all-match`).
+
When `--show-notes` is in effect, the message from the notes as
if it is part of the log message.

--all-match::
	Limit the commits output to ones that match all given --grep,
	instead of ones that match at least one.

-i::
--regexp-ignore-case::

	Match the regexp limiting patterns without regard to letters case.

--basic-regexp::

	Consider the limiting patterns to be basic regular expressions;
	this is the default.

-E::
--extended-regexp::

	Consider the limiting patterns to be extended regular expressions
	instead of the default basic regular expressions.

-F::
--fixed-strings::

	Consider the limiting patterns to be fixed strings (don't interpret
	pattern as a regular expression).

--perl-regexp::

	Consider the limiting patterns to be Perl-compatible regexp.
	Requires libpcre to be compiled in.

--remove-empty::

	Stop when a given path disappears from the tree.

--merges::

	Print only merge commits. This is exactly the same as `--min-parents=2`.

--no-merges::

	Do not print commits with more than one parent. This is
	exactly the same as `--max-parents=1`.

--min-parents=<number>::
--max-parents=<number>::
--no-min-parents::
--no-max-parents::

	Show only commits which have at least (or at most) that many
	commits. In particular, `--max-parents=1` is the same as `--no-merges`,
	`--min-parents=2` is the same as `--merges`.  `--max-parents=0`
	gives all root commits and `--min-parents=3` all octopus merges.
+
`--no-min-parents` and `--no-max-parents` reset these limits (to no limit)
again.  Equivalent forms are `--min-parents=0` (any commit has 0 or more
parents) and `--max-parents=-1` (negative numbers denote no upper limit).

--first-parent::
	Follow only the first parent commit upon seeing a merge
	commit.  This option can give a better overview when
	viewing the evolution of a particular topic branch,
	because merges into a topic branch tend to be only about
	adjusting to updated upstream from time to time, and
	this option allows you to ignore the individual commits
	brought in to your history by such a merge.

--not::

	Reverses the meaning of the '{caret}' prefix (or lack thereof)
	for all following revision specifiers, up to the next '--not'.

--all::

	Pretend as if all the refs in `refs/` are listed on the
	command line as '<commit>'.

--branches[=<pattern>]::

	Pretend as if all the refs in `refs/heads` are listed
	on the command line as '<commit>'. If '<pattern>' is given, limit
	branches to ones matching given shell glob. If pattern lacks '?',
	'{asterisk}', or '[', '/{asterisk}' at the end is implied.

--tags[=<pattern>]::

	Pretend as if all the refs in `refs/tags` are listed
	on the command line as '<commit>'. If '<pattern>' is given, limit
	tags to ones matching given shell glob. If pattern lacks '?', '{asterisk}',
	or '[', '/{asterisk}' at the end is implied.

--remotes[=<pattern>]::

	Pretend as if all the refs in `refs/remotes` are listed
	on the command line as '<commit>'. If '<pattern>' is given, limit
	remote-tracking branches to ones matching given shell glob.
	If pattern lacks '?', '{asterisk}', or '[', '/{asterisk}' at the end is implied.

--glob=<glob-pattern>::
	Pretend as if all the refs matching shell glob '<glob-pattern>'
	are listed on the command line as '<commit>'. Leading 'refs/',
	is automatically prepended if missing. If pattern lacks '?', '{asterisk}',
	or '[', '/{asterisk}' at the end is implied.

--ignore-missing::

	Upon seeing an invalid object name in the input, pretend as if
	the bad input was not given.

ifndef::git-rev-list[]
--bisect::

	Pretend as if the bad bisection ref `refs/bisect/bad`
	was listed and as if it was followed by `--not` and the good
	bisection refs `refs/bisect/good-*` on the command
	line.
endif::git-rev-list[]

--stdin::

	In addition to the '<commit>' listed on the command
	line, read them from the standard input. If a '--' separator is
	seen, stop reading commits and start reading paths to limit the
	result.

ifdef::git-rev-list[]
--quiet::

	Don't print anything to standard output.  This form
	is primarily meant to allow the caller to
	test the exit status to see if a range of objects is fully
	connected (or not).  It is faster than redirecting stdout
	to /dev/null as the output does not have to be formatted.
endif::git-rev-list[]

--cherry-mark::

	Like `--cherry-pick` (see below) but mark equivalent commits
	with `=` rather than omitting them, and inequivalent ones with `+`.

--cherry-pick::

	Omit any commit that introduces the same change as
	another commit on the "other side" when the set of
	commits are limited with symmetric difference.
+
For example, if you have two branches, `A` and `B`, a usual way
to list all commits on only one side of them is with
`--left-right` (see the example below in the description of
the `--left-right` option).  It however shows the commits that were cherry-picked
from the other branch (for example, "3rd on b" may be cherry-picked
from branch A).  With this option, such pairs of commits are
excluded from the output.

--left-only::
--right-only::

	List only commits on the respective side of a symmetric range,
	i.e. only those which would be marked `<` resp. `>` by
	`--left-right`.
+
For example, `--cherry-pick --right-only A...B` omits those
commits from `B` which are in `A` or are patch-equivalent to a commit in
`A`. In other words, this lists the `+` commits from `git cherry A B`.
More precisely, `--cherry-pick --right-only --no-merges` gives the exact
list.

--cherry::

	A synonym for `--right-only --cherry-mark --no-merges`; useful to
	limit the output to the commits on our side and mark those that
	have been applied to the other side of a forked history with
	`git log --cherry upstream...mybranch`, similar to
	`git cherry upstream mybranch`.

-g::
--walk-reflogs::

	Instead of walking the commit ancestry chain, walk
	reflog entries from the most recent one to older ones.
	When this option is used you cannot specify commits to
	exclude (that is, '{caret}commit', 'commit1..commit2',
	nor 'commit1\...commit2' notations cannot be used).
+
With '\--pretty' format other than oneline (for obvious reasons),
this causes the output to have two extra lines of information
taken from the reflog.  By default, 'commit@\{Nth}' notation is
used in the output.  When the starting commit is specified as
'commit@\{now}', output also uses 'commit@\{timestamp}' notation
instead.  Under '\--pretty=oneline', the commit message is
prefixed with this information on the same line.
This option cannot be combined with '\--reverse'.
See also linkgit:git-reflog[1].

--merge::

	After a failed merge, show refs that touch files having a
	conflict and don't exist on all heads to merge.

--boundary::

	Output excluded boundary commits. Boundary commits are
	prefixed with `-`.

--

History Simplification
~~~~~~~~~~~~~~~~~~~~~~

Sometimes you are only interested in parts of the history, for example the
commits modifying a particular <path>. But there are two parts of
'History Simplification', one part is selecting the commits and the other
is how to do it, as there are various strategies to simplify the history.

The following options select the commits to be shown:

<paths>::

	Commits modifying the given <paths> are selected.

--simplify-by-decoration::

	Commits that are referred by some branch or tag are selected.

Note that extra commits can be shown to give a meaningful history.

The following options affect the way the simplification is performed:

Default mode::

	Simplifies the history to the simplest history explaining the
	final state of the tree. Simplest because it prunes some side
	branches if the end result is the same (i.e. merging branches
	with the same content)

--full-history::

	Same as the default mode, but does not prune some history.

--dense::

	Only the selected commits are shown, plus some to have a
	meaningful history.

--sparse::

	All commits in the simplified history are shown.

--simplify-merges::

	Additional option to '--full-history' to remove some needless
	merges from the resulting history, as there are no selected
	commits contributing to this merge.

--ancestry-path::

	When given a range of commits to display (e.g. 'commit1..commit2'
	or 'commit2 {caret}commit1'), only display commits that exist
	directly on the ancestry chain between the 'commit1' and
	'commit2', i.e. commits that are both descendants of 'commit1',
	and ancestors of 'commit2'.

A more detailed explanation follows.

Suppose you specified `foo` as the <paths>.  We shall call commits
that modify `foo` !TREESAME, and the rest TREESAME.  (In a diff
filtered for `foo`, they look different and equal, respectively.)

In the following, we will always refer to the same example history to
illustrate the differences between simplification settings.  We assume
that you are filtering for a file `foo` in this commit graph:
-----------------------------------------------------------------------
	  .-A---M---N---O---P
	 /     /   /   /   /
	I     B   C   D   E
	 \   /   /   /   /
	  `-------------'
-----------------------------------------------------------------------
The horizontal line of history A---P is taken to be the first parent of
each merge.  The commits are:

* `I` is the initial commit, in which `foo` exists with contents
  "asdf", and a file `quux` exists with contents "quux".  Initial
  commits are compared to an empty tree, so `I` is !TREESAME.

* In `A`, `foo` contains just "foo".

* `B` contains the same change as `A`.  Its merge `M` is trivial and
  hence TREESAME to all parents.

* `C` does not change `foo`, but its merge `N` changes it to "foobar",
  so it is not TREESAME to any parent.

* `D` sets `foo` to "baz".  Its merge `O` combines the strings from
  `N` and `D` to "foobarbaz"; i.e., it is not TREESAME to any parent.

* `E` changes `quux` to "xyzzy", and its merge `P` combines the
  strings to "quux xyzzy".  `P` is TREESAME to `O`, but not to `E`.

'rev-list' walks backwards through history, including or excluding
commits based on whether '\--full-history' and/or parent rewriting
(via '\--parents' or '\--children') are used.  The following settings
are available.

Default mode::

	Commits are included if they are not TREESAME to any parent
	(though this can be changed, see '\--sparse' below).  If the
	commit was a merge, and it was TREESAME to one parent, follow
	only that parent.  (Even if there are several TREESAME
	parents, follow only one of them.)  Otherwise, follow all
	parents.
+
This results in:
+
-----------------------------------------------------------------------
	  .-A---N---O
	 /     /   /
	I---------D
-----------------------------------------------------------------------
+
Note how the rule to only follow the TREESAME parent, if one is
available, removed `B` from consideration entirely.  `C` was
considered via `N`, but is TREESAME.  Root commits are compared to an
empty tree, so `I` is !TREESAME.
+
Parent/child relations are only visible with --parents, but that does
not affect the commits selected in default mode, so we have shown the
parent lines.

--full-history without parent rewriting::

	This mode differs from the default in one point: always follow
	all parents of a merge, even if it is TREESAME to one of them.
	Even if more than one side of the merge has commits that are
	included, this does not imply that the merge itself is!  In
	the example, we get
+
-----------------------------------------------------------------------
	I  A  B  N  D  O  P
-----------------------------------------------------------------------
+
`M` was excluded because it is TREESAME to both parents.  `E`,
`C` and `B` were all walked, but only `B` was !TREESAME, so the others
do not appear.
+
Note that without parent rewriting, it is not really possible to talk
about the parent/child relationships between the commits, so we show
them disconnected.

--full-history with parent rewriting::

	Ordinary commits are only included if they are !TREESAME
	(though this can be changed, see '\--sparse' below).
+
Merges are always included.  However, their parent list is rewritten:
Along each parent, prune away commits that are not included
themselves.  This results in
+
-----------------------------------------------------------------------
	  .-A---M---N---O---P
	 /     /   /   /   /
	I     B   /   D   /
	 \   /   /   /   /
	  `-------------'
-----------------------------------------------------------------------
+
Compare to '\--full-history' without rewriting above.  Note that `E`
was pruned away because it is TREESAME, but the parent list of P was
rewritten to contain `E`'s parent `I`.  The same happened for `C` and
`N`.

In addition to the above settings, you can change whether TREESAME
affects inclusion:

--dense::

	Commits that are walked are included if they are not TREESAME
	to any parent.

--sparse::

	All commits that are walked are included.
+
Note that without '\--full-history', this still simplifies merges: if
one of the parents is TREESAME, we follow only that one, so the other
sides of the merge are never walked.

--simplify-merges::

	First, build a history graph in the same way that
	'\--full-history' with parent rewriting does (see above).
+
Then simplify each commit `C` to its replacement `C'` in the final
history according to the following rules:
+
--
* Set `C'` to `C`.
+
* Replace each parent `P` of `C'` with its simplification `P'`.  In
  the process, drop parents that are ancestors of other parents, and
  remove duplicates, but take care to never drop all parents that
  we are TREESAME to.
+
* If after this parent rewriting, `C'` is a root or merge commit (has
  zero or >1 parents), a boundary commit, or !TREESAME, it remains.
  Otherwise, it is replaced with its only parent.
--
+
The effect of this is best shown by way of comparing to
'\--full-history' with parent rewriting.  The example turns into:
+
-----------------------------------------------------------------------
	  .-A---M---N---O
	 /     /       /
	I     B       D
	 \   /       /
	  `---------'
-----------------------------------------------------------------------
+
Note the major differences in `N` and `P` over '--full-history':
+
--
* `N`'s parent list had `I` removed, because it is an ancestor of the
  other parent `M`.  Still, `N` remained because it is !TREESAME.
+
* `P`'s parent list similarly had `I` removed.  `P` was then
  removed completely, because it had one parent and is TREESAME.
--

Finally, there is a fifth simplification mode available:

--ancestry-path::

	Limit the displayed commits to those directly on the ancestry
	chain between the "from" and "to" commits in the given commit
	range. I.e. only display commits that are ancestor of the "to"
	commit, and descendants of the "from" commit.
+
As an example use case, consider the following commit history:
+
-----------------------------------------------------------------------
	    D---E-------F
	   /     \       \
	  B---C---G---H---I---J
	 /                     \
	A-------K---------------L--M
-----------------------------------------------------------------------
+
A regular 'D..M' computes the set of commits that are ancestors of `M`,
but excludes the ones that are ancestors of `D`. This is useful to see
what happened to the history leading to `M` since `D`, in the sense
that "what does `M` have that did not exist in `D`". The result in this
example would be all the commits, except `A` and `B` (and `D` itself,
of course).
+
When we want to find out what commits in `M` are contaminated with the
bug introduced by `D` and need fixing, however, we might want to view
only the subset of 'D..M' that are actually descendants of `D`, i.e.
excluding `C` and `K`. This is exactly what the '--ancestry-path'
option does. Applied to the 'D..M' range, it results in:
+
-----------------------------------------------------------------------
		E-------F
		 \       \
		  G---H---I---J
			       \
				L--M
-----------------------------------------------------------------------

The '\--simplify-by-decoration' option allows you to view only the
big picture of the topology of the history, by omitting commits
that are not referenced by tags.  Commits are marked as !TREESAME
(in other words, kept after history simplification rules described
above) if (1) they are referenced by tags, or (2) they change the
contents of the paths given on the command line.  All other
commits are marked as TREESAME (subject to be simplified away).

ifdef::git-rev-list[]
Bisection Helpers
~~~~~~~~~~~~~~~~~

--bisect::

Limit output to the one commit object which is roughly halfway between
included and excluded commits. Note that the bad bisection ref
`refs/bisect/bad` is added to the included commits (if it
exists) and the good bisection refs `refs/bisect/good-*` are
added to the excluded commits (if they exist). Thus, supposing there
are no refs in `refs/bisect/`, if

-----------------------------------------------------------------------
	$ git rev-list --bisect foo ^bar ^baz
-----------------------------------------------------------------------

outputs 'midpoint', the output of the two commands

-----------------------------------------------------------------------
	$ git rev-list foo ^midpoint
	$ git rev-list midpoint ^bar ^baz
-----------------------------------------------------------------------

would be of roughly the same length.  Finding the change which
introduces a regression is thus reduced to a binary search: repeatedly
generate and test new 'midpoint's until the commit chain is of length
one.

--bisect-vars::

This calculates the same as `--bisect`, except that refs in
`refs/bisect/` are not used, and except that this outputs
text ready to be eval'ed by the shell. These lines will assign the
name of the midpoint revision to the variable `bisect_rev`, and the
expected number of commits to be tested after `bisect_rev` is tested
to `bisect_nr`, the expected number of commits to be tested if
`bisect_rev` turns out to be good to `bisect_good`, the expected
number of commits to be tested if `bisect_rev` turns out to be bad to
`bisect_bad`, and the number of commits we are bisecting right now to
`bisect_all`.

--bisect-all::

This outputs all the commit objects between the included and excluded
commits, ordered by their distance to the included and excluded
commits. Refs in `refs/bisect/` are not used. The farthest
from them is displayed first. (This is the only one displayed by
`--bisect`.)
+
This is useful because it makes it easy to choose a good commit to
test when you want to avoid to test some of them for some reason (they
may not compile for example).
+
This option can be used along with `--bisect-vars`, in this case,
after all the sorted commit objects, there will be the same text as if
`--bisect-vars` had been used alone.
endif::git-rev-list[]


Commit Ordering
~~~~~~~~~~~~~~~

By default, the commits are shown in reverse chronological order.

--date-order::
	Show no parents before all of its children are shown, but
	otherwise show commits in the commit timestamp order.

--topo-order::
	Show no parents before all of its children are shown, and
	avoid showing commits on multiple lines of history
	intermixed.
+
For example, in a commit history like this:
+
----------------------------------------------------------------

    ---1----2----4----7
	\	       \
	 3----5----6----8---

----------------------------------------------------------------
+
where the numbers denote the order of commit timestamps, `git
rev-list` and friends with `--date-order` show the commits in the
timestamp order: 8 7 6 5 4 3 2 1.
+
With `--topo-order`, they would show 8 6 5 3 7 4 2 1 (or 8 7 4 2 6 5
3 1); some older commits are shown before newer ones in order to
avoid showing the commits from two parallel development track mixed
together.

--reverse::

	Output the commits in reverse order.
	Cannot be combined with '\--walk-reflogs'.

Object Traversal
~~~~~~~~~~~~~~~~

These options are mostly targeted for packing of Git repositories.

--objects::

	Print the object IDs of any object referenced by the listed
	commits.  '--objects foo ^bar' thus means "send me
	all object IDs which I need to download if I have the commit
	object 'bar', but not 'foo'".

--objects-edge::

	Similar to '--objects', but also print the IDs of excluded
	commits prefixed with a "-" character.  This is used by
	linkgit:git-pack-objects[1] to build "thin" pack, which records
	objects in deltified form based on objects contained in these
	excluded commits to reduce network traffic.

--unpacked::

	Only useful with '--objects'; print the object IDs that are not
	in packs.

--no-walk[=(sorted|unsorted)]::

	Only show the given commits, but do not traverse their ancestors.
	This has no effect if a range is specified. If the argument
	"unsorted" is given, the commits are show in the order they were
	given on the command line. Otherwise (if "sorted" or no argument
	was given), the commits are show in reverse chronological order
	by commit time.

--do-walk::

	Overrides a previous --no-walk.

Commit Formatting
~~~~~~~~~~~~~~~~~

ifdef::git-rev-list[]
Using these options, linkgit:git-rev-list[1] will act similar to the
more specialized family of commit log tools: linkgit:git-log[1],
linkgit:git-show[1], and linkgit:git-whatchanged[1]
endif::git-rev-list[]

include::pretty-options.txt[]

--relative-date::

	Synonym for `--date=relative`.

--date=(relative|local|default|iso|rfc|short|raw)::

	Only takes effect for dates shown in human-readable format, such
	as when using "--pretty". `log.date` config variable sets a default
	value for log command's --date option.
+
`--date=relative` shows dates relative to the current time,
e.g. "2 hours ago".
+
`--date=local` shows timestamps in user's local timezone.
+
`--date=iso` (or `--date=iso8601`) shows timestamps in ISO 8601 format.
+
`--date=rfc` (or `--date=rfc2822`) shows timestamps in RFC 2822
format, often found in E-mail messages.
+
`--date=short` shows only date but not time, in `YYYY-MM-DD` format.
+
`--date=raw` shows the date in the internal raw Git format `%s %z` format.
+
`--date=default` shows timestamps in the original timezone
(either committer's or author's).

ifdef::git-rev-list[]
--header::

	Print the contents of the commit in raw-format; each record is
	separated with a NUL character.
endif::git-rev-list[]

--parents::

	Print also the parents of the commit (in the form "commit parent...").
	Also enables parent rewriting, see 'History Simplification' below.

--children::

	Print also the children of the commit (in the form "commit child...").
	Also enables parent rewriting, see 'History Simplification' below.

ifdef::git-rev-list[]
--timestamp::
	Print the raw commit timestamp.
endif::git-rev-list[]

--left-right::

	Mark which side of a symmetric diff a commit is reachable from.
	Commits from the left side are prefixed with `<` and those from
	the right with `>`.  If combined with `--boundary`, those
	commits are prefixed with `-`.
+
For example, if you have this topology:
+
-----------------------------------------------------------------------
	     y---b---b  branch B
	    / \ /
	   /   .
	  /   / \
	 o---x---a---a  branch A
-----------------------------------------------------------------------
+
you would get an output like this:
+
-----------------------------------------------------------------------
	$ git rev-list --left-right --boundary --pretty=oneline A...B

	>bbbbbbb... 3rd on b
	>bbbbbbb... 2nd on b
	<aaaaaaa... 3rd on a
	<aaaaaaa... 2nd on a
	-yyyyyyy... 1st on b
	-xxxxxxx... 1st on a
-----------------------------------------------------------------------

--graph::

	Draw a text-based graphical representation of the commit history
	on the left hand side of the output.  This may cause extra lines
	to be printed in between commits, in order for the graph history
	to be drawn properly.
+
This enables parent rewriting, see 'History Simplification' below.
+
This implies the '--topo-order' option by default, but the
'--date-order' option may also be specified.

ifdef::git-rev-list[]
--count::
	Print a number stating how many commits would have been
	listed, and suppress all other output.  When used together
	with '--left-right', instead print the counts for left and
	right commits, separated by a tab. When used together with
	'--cherry-mark', omit patch equivalent commits from these
	counts and print the count for equivalent commits separated
	by a tab.
endif::git-rev-list[]


ifndef::git-rev-list[]
Diff Formatting
~~~~~~~~~~~~~~~

Below are listed options that control the formatting of diff output.
Some of them are specific to linkgit:git-rev-list[1], however other diff
options may be given. See linkgit:git-diff-files[1] for more options.

-c::

	With this option, diff output for a merge commit
	shows the differences from each of the parents to the merge result
	simultaneously instead of showing pairwise diff between a parent
	and the result one at a time. Furthermore, it lists only files
	which were modified from all parents.

--cc::

	This flag implies the '-c' option and further compresses the
	patch output by omitting uninteresting hunks whose contents in
	the parents have only two variants and the merge result picks
	one of them without modification.

-m::

	This flag makes the merge commits show the full diff like
	regular commits; for each merge parent, a separate log entry
	and diff is generated. An exception is that only diff against
	the first parent is shown when '--first-parent' option is given;
	in that case, the output represents the changes the merge
	brought _into_ the then-current branch.

-r::

	Show recursive diffs.

-t::

	Show the tree objects in the diff output. This implies '-r'.

-s::
	Suppress diff output.
endif::git-rev-list[]