mercurial/help/patterns.txt

backout: make help more explicit about what backout does

The help for backout explains:

   The backout command merges the reverse effect of the reverted
   changeset into the working directory.

Unfortunately, that does not make it obvious to a newcomer what the
backout command does.  Since it performs a 3-way merge, what is the
common ancestor?  Will the result be automatically committed?  What is
this reverted changeset --- is it the rev passed with -r on the
command line or its inverse?

So try to clarify the description, avoiding jargon and being
explicit about what happens from the user's perspective.

Thanks to Gilles Moris, Steve Borho, Kevin Bullock, and timeless for
help.

Mercurial accepts several notations for identifying one or more files
at a time.

By default, Mercurial treats filenames as shell-style extended glob
patterns.

Alternate pattern notations must be specified explicitly.

To use a plain path name without any pattern matching, start it with
``path:``. These path names must completely match starting at the
current repository root.

To use an extended glob, start a name with ``glob:``. Globs are rooted
at the current directory; a glob such as ``*.c`` will only match files
in the current directory ending with ``.c``.

The supported glob syntax extensions are ``**`` to match any string
across path separators and ``{a,b}`` to mean "a or b".

To use a Perl/Python regular expression, start a name with ``re:``.
Regexp pattern matching is anchored at the root of the repository.

Plain examples::

  path:foo/bar   a name bar in a directory named foo in the root
                 of the repository
  path:path:name a file or directory named "path:name"

Glob examples::

  glob:*.c       any name ending in ".c" in the current directory
  *.c            any name ending in ".c" in the current directory
  **.c           any name ending in ".c" in any subdirectory of the
                 current directory including itself.
  foo/*.c        any name ending in ".c" in the directory foo
  foo/**.c       any name ending in ".c" in any subdirectory of foo
                 including itself.

Regexp examples::

  re:.*\.c$      any name ending in ".c", anywhere in the repository