log
===

:Purpose: Show historical log for a branch or subset of a branch.
:Usage:   brz log [FILE...]

:Options:
  --authors=ARG         What names to list as authors - first, all or
                        committer.
  -c ARG, --change=ARG  Show just the specified revision. See also "help
                        revisionspec".
  --exclude-common-ancestry
                        Display only the revisions that are not part of both
                        ancestries (require -rX..Y).
  --forward             Show from oldest to newest.
  -h, --help            Show help message.
  --include-merged      Show merged revisions like --levels 0 does.
  -n N, --levels=N      Number of levels to display - 0 for all, 1 for flat.
  -l N, --limit=N       Limit the output to the first N revisions.
  -m ARG, --match=ARG   Show revisions whose properties match this expression.
  --match-author=ARG    Show revisions whose authors match this expression.
  --match-bugs=ARG      Show revisions whose bugs match this expression.
  --match-committer=ARG
                        Show revisions whose committer matches this
                        expression.
  --match-message=ARG   Show revisions whose message matches this expression.
  --omit-merges         Do not report commits with more than one parent.
  -q, --quiet           Only display errors and warnings.
  -r ARG, --revision=ARG
                        See "help revisionspec" for details.
  -p, --show-diff       Show changes made in each revision as a patch.
  --show-ids            Show internal object ids.
  --signatures          Show digital signature validity.
  --timezone=ARG        Display timezone as local, original, or utc.
  --usage               Show usage message and options.
  -v, --verbose         Show files changed in each revision.

  Log format:
    --log-format=ARG    Use specified log format.
    --gnu-changelog     Format used by GNU ChangeLog files.
    --line              Log format with one line per revision.
    --long              Detailed log format.
    -S, --short         Moderately short log format.

:Description:
  log is brz's default tool for exploring the history of a branch.
  The branch to use is taken from the first parameter. If no parameters
  are given, the branch containing the working directory is logged.
  Here are some simple examples::
  
    brz log                       log the current branch
    brz log foo.py                log a file in its branch
    brz log http://server/branch  log a branch on a server
  
  The filtering, ordering and information shown for each revision can
  be controlled as explained below. By default, all revisions are
  shown sorted (topologically) so that newer revisions appear before
  older ones and descendants always appear before ancestors. If displayed,
  merged revisions are shown indented under the revision in which they
  were merged.

:Output control:
  The log format controls how information about each revision is
  displayed. The standard log formats are called ``long``, ``short``
  and ``line``. The default is long. See ``brz help log-formats``
  for more details on log formats.

  The following options can be used to control what information is
  displayed::

    -l N        display a maximum of N revisions
    -n N        display N levels of revisions (0 for all, 1 for collapsed)
    -v          display a status summary (delta) for each revision
    -p          display a diff (patch) for each revision
    --show-ids  display revision-ids (and file-ids), not just revnos

  Note that the default number of levels to display is a function of the
  log format. If the -n option is not used, the standard log formats show
  just the top level (mainline).

  Status summaries are shown using status flags like A, M, etc. To see
  the changes explained using words like ``added`` and ``modified``
  instead, use the -vv option.

:Ordering control:
  To display revisions from oldest to newest, use the --forward option.
  In most cases, using this option will have little impact on the total
  time taken to produce a log, though --forward does not incrementally
  display revisions like --reverse does when it can.

:Revision filtering:
  The -r option can be used to specify what revision or range of revisions
  to filter against. The various forms are shown below::

    -rX      display revision X
    -rX..    display revision X and later
    -r..Y    display up to and including revision Y
    -rX..Y   display from X to Y inclusive

  See ``brz help revisionspec`` for details on how to specify X and Y.
  Some common examples are given below::

    -r-1                show just the tip
    -r-10..             show the last 10 mainline revisions
    -rsubmit:..         show what's new on this branch
    -rancestor:path..   show changes since the common ancestor of this
                        branch and the one at location path
    -rdate:yesterday..  show changes since yesterday

  When logging a range of revisions using -rX..Y, log starts at
  revision Y and searches back in history through the primary
  ("left-hand") parents until it finds X. When logging just the
  top level (using -n1), an error is reported if X is not found
  along the way. If multi-level logging is used (-n0), X may be
  a nested merge revision and the log will be truncated accordingly.

:Path filtering:
  If parameters are given and the first one is not a branch, the log
  will be filtered to show only those revisions that changed the
  nominated files or directories.

  Filenames are interpreted within their historical context. To log a
  deleted file, specify a revision range so that the file existed at
  the end or start of the range.

  Historical context is also important when interpreting pathnames of
  renamed files/directories. Consider the following example:

  * revision 1: add tutorial.txt
  * revision 2: modify tutorial.txt
  * revision 3: rename tutorial.txt to guide.txt; add tutorial.txt

  In this case:

  * ``brz log guide.txt`` will log the file added in revision 1

  * ``brz log tutorial.txt`` will log the new file added in revision 3

  * ``brz log -r2 -p tutorial.txt`` will show the changes made to
    the original file in revision 2.

  * ``brz log -r2 -p guide.txt`` will display an error message as there
    was no file called guide.txt in revision 2.

  Renames are always followed by log. By design, there is no need to
  explicitly ask for this (and no way to stop logging a file back
  until it was last renamed).

:Other filtering:
  The --match option can be used for finding revisions that match a
  regular expression in a commit message, committer, author or bug.
  Specifying the option several times will match any of the supplied
  expressions. --match-author, --match-bugs, --match-committer and
  --match-message can be used to only match a specific field.

:Tips & tricks:
  GUI tools and IDEs are often better at exploring history than command
  line tools: you may prefer qlog from qbzr, or the Loggerhead web
  interface.  See the Breezy
  Plugin Guide <https://www.breezy-vcs.org/doc/plugins/en/> and
  <http://wiki.breezy-vcs.org/IDEIntegration>.

  You may find it useful to add the aliases below to ``breezy.conf``::

    [ALIASES]
    tip = log -r-1
    top = log -l10 --line
    show = log -v -p

  ``brz tip`` will then show the latest revision while ``brz top``
  will show the last 10 mainline revisions. To see the details of a
  particular revision X,  ``brz show -rX``.

  If you are interested in looking deeper into a particular merge X,
  use ``brz log -n0 -rX``.

  ``brz log -v`` on a branch with lots of history is currently
  very slow. A fix for this issue is currently under development.
  With or without that fix, it is recommended that a revision range
  be given when using the -v option.

  brz has a generic full-text matching plugin, brz-search, that can be
  used to find revisions matching user names, commit messages, etc.
  Among other features, this plugin can find all revisions containing
  a list of words but not others.

  When exploring non-mainline history on large projects with deep
  history, the performance of log can be greatly improved by installing
  the historycache plugin. This plugin buffers historical information
  trading disk space for faster speed.

:See also: :doc:`log-formats <log-formats-help>`, :doc:`revisionspec <revisionspec-help>`


