git-commit-vandalism/Documentation/git-log.txt
Jeff King 5fbb4bc191 doc/git-log: clarify handling of merge commit diffs
It can be surprising that git-log doesn't show any diff for merge
commits by default. Arguably "--cc" would be a reasonable default, but
it's very expensive (which is why we turn it on for "git show" but not
for "git log"). Let's at least document the current behavior, including
the recent "--first-parent implies -m" case

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-07-29 13:44:03 -07:00

283 lines
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git-log(1)
==========
NAME
----
git-log - Show commit logs
SYNOPSIS
--------
[verse]
'git log' [<options>] [<revision range>] [[--] <path>...]
DESCRIPTION
-----------
Shows the commit logs.
The command takes options applicable to the `git rev-list`
command to control what is shown and how, and options applicable to
the `git diff-*` commands to control how the changes
each commit introduces are shown.
OPTIONS
-------
--follow::
Continue listing the history of a file beyond renames
(works only for a single file).
--no-decorate::
--decorate[=short|full|auto|no]::
Print out the ref names of any commits that are shown. If 'short' is
specified, the ref name prefixes 'refs/heads/', 'refs/tags/' and
'refs/remotes/' will not be printed. If 'full' is specified, the
full ref name (including prefix) will be printed. If 'auto' is
specified, then if the output is going to a terminal, the ref names
are shown as if 'short' were given, otherwise no ref names are
shown. The default option is 'short'.
--decorate-refs=<pattern>::
--decorate-refs-exclude=<pattern>::
If no `--decorate-refs` is given, pretend as if all refs were
included. For each candidate, do not use it for decoration if it
matches any patterns given to `--decorate-refs-exclude` or if it
doesn't match any of the patterns given to `--decorate-refs`. The
`log.excludeDecoration` config option allows excluding refs from
the decorations, but an explicit `--decorate-refs` pattern will
override a match in `log.excludeDecoration`.
--source::
Print out the ref name given on the command line by which each
commit was reached.
--[no-]mailmap::
--[no-]use-mailmap::
Use mailmap file to map author and committer names and email
addresses to canonical real names and email addresses. See
linkgit:git-shortlog[1].
--full-diff::
Without this flag, `git log -p <path>...` shows commits that
touch the specified paths, and diffs about the same specified
paths. With this, the full diff is shown for commits that touch
the specified paths; this means that "<path>..." limits only
commits, and doesn't limit diff for those commits.
+
Note that this affects all diff-based output types, e.g. those
produced by `--stat`, etc.
--log-size::
Include a line ``log size <number>'' in the output for each commit,
where <number> is the length of that commit's message in bytes.
Intended to speed up tools that read log messages from `git log`
output by allowing them to allocate space in advance.
-L <start>,<end>:<file>::
-L :<funcname>:<file>::
Trace the evolution of the line range given by "<start>,<end>"
(or the function name regex <funcname>) within the <file>. You may
not give any pathspec limiters. This is currently limited to
a walk starting from a single revision, i.e., you may only
give zero or one positive revision arguments, and
<start> and <end> (or <funcname>) must exist in the starting revision.
You can specify this option more than once. Implies `--patch`.
Patch output can be suppressed using `--no-patch`, but other diff formats
(namely `--raw`, `--numstat`, `--shortstat`, `--dirstat`, `--summary`,
`--name-only`, `--name-status`, `--check`) are not currently implemented.
+
include::line-range-format.txt[]
<revision range>::
Show only commits in the specified revision range. When no
<revision range> is specified, it defaults to `HEAD` (i.e. the
whole history leading to the current commit). `origin..HEAD`
specifies all the commits reachable from the current commit
(i.e. `HEAD`), but not from `origin`. For a complete list of
ways to spell <revision range>, see the 'Specifying Ranges'
section of linkgit:gitrevisions[7].
[--] <path>...::
Show only commits that are enough to explain how the files
that match the specified paths came to be. See 'History
Simplification' below for details and other simplification
modes.
+
Paths may need to be prefixed with `--` to separate them from
options or the revision range, when confusion arises.
include::rev-list-options.txt[]
include::pretty-formats.txt[]
DIFF FORMATTING
---------------
By default, `git log` does not generate any diff output. The options
below can be used to show the changes made by each commit.
Note that unless one of `-c`, `--cc`, or `-m` is given, merge commits
will never show a diff, even if a diff format like `--patch` is
selected, nor will they match search options like `-S`. The exception is
when `--first-parent` is in use, in which merges are treated like normal
single-parent commits (this can be overridden by providing a
combined-diff option or with `--no-diff-merges`).
-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.
--combined-all-paths::
This flag causes combined diffs (used for merge commits) to
list the name of the file from all parents. It thus only has
effect when -c or --cc are specified, and is likely only
useful if filename changes are detected (i.e. when either
rename or copy detection have been requested).
-m::
--diff-merges::
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.
:git-log: 1
include::diff-options.txt[]
include::diff-generate-patch.txt[]
EXAMPLES
--------
`git log --no-merges`::
Show the whole commit history, but skip any merges
`git log v2.6.12.. include/scsi drivers/scsi`::
Show all commits since version 'v2.6.12' that changed any file
in the `include/scsi` or `drivers/scsi` subdirectories
`git log --since="2 weeks ago" -- gitk`::
Show the changes during the last two weeks to the file 'gitk'.
The `--` is necessary to avoid confusion with the *branch* named
'gitk'
`git log --name-status release..test`::
Show the commits that are in the "test" branch but not yet
in the "release" branch, along with the list of paths
each commit modifies.
`git log --follow builtin/rev-list.c`::
Shows the commits that changed `builtin/rev-list.c`, including
those commits that occurred before the file was given its
present name.
`git log --branches --not --remotes=origin`::
Shows all commits that are in any of local branches but not in
any of remote-tracking branches for 'origin' (what you have that
origin doesn't).
`git log master --not --remotes=*/master`::
Shows all commits that are in local master but not in any remote
repository master branches.
`git log -p -m --first-parent`::
Shows the history including change diffs, but only from the
``main branch'' perspective, skipping commits that come from merged
branches, and showing full diffs of changes introduced by the merges.
This makes sense only when following a strict policy of merging all
topic branches when staying on a single integration branch.
`git log -L '/int main/',/^}/:main.c`::
Shows how the function `main()` in the file `main.c` evolved
over time.
`git log -3`::
Limits the number of commits to show to 3.
DISCUSSION
----------
include::i18n.txt[]
CONFIGURATION
-------------
See linkgit:git-config[1] for core variables and linkgit:git-diff[1]
for settings related to diff generation.
format.pretty::
Default for the `--format` option. (See 'Pretty Formats' above.)
Defaults to `medium`.
i18n.logOutputEncoding::
Encoding to use when displaying logs. (See 'Discussion' above.)
Defaults to the value of `i18n.commitEncoding` if set, and UTF-8
otherwise.
log.date::
Default format for human-readable dates. (Compare the
`--date` option.) Defaults to "default", which means to write
dates like `Sat May 8 19:35:34 2010 -0500`.
+
If the format is set to "auto:foo" and the pager is in use, format
"foo" will be the used for the date format. Otherwise "default" will
be used.
log.follow::
If `true`, `git log` will act as if the `--follow` option was used when
a single <path> is given. This has the same limitations as `--follow`,
i.e. it cannot be used to follow multiple files and does not work well
on non-linear history.
log.showRoot::
If `false`, `git log` and related commands will not treat the
initial commit as a big creation event. Any root commits in
`git log -p` output would be shown without a diff attached.
The default is `true`.
log.showSignature::
If `true`, `git log` and related commands will act as if the
`--show-signature` option was passed to them.
mailmap.*::
See linkgit:git-shortlog[1].
notes.displayRef::
Which refs, in addition to the default set by `core.notesRef`
or `GIT_NOTES_REF`, to read notes from when showing commit
messages with the `log` family of commands. See
linkgit:git-notes[1].
+
May be an unabbreviated ref name or a glob and may be specified
multiple times. A warning will be issued for refs that do not exist,
but a glob that does not match any refs is silently ignored.
+
This setting can be disabled by the `--no-notes` option,
overridden by the `GIT_NOTES_DISPLAY_REF` environment variable,
and overridden by the `--notes=<ref>` option.
GIT
---
Part of the linkgit:git[1] suite