view mercurial/helptext/patterns.txt @ 45095:8e04607023e5

procutil: ensure that procutil.std{out,err}.write() writes all bytes

Python 3 offers different kind of streams and it’s not guaranteed for all of
them that calling write() writes all bytes.

When Python is started in unbuffered mode, sys.std{out,err}.buffer are
instances of io.FileIO, whose write() can write less bytes for
platform-specific reasons (e.g. Linux has a 0x7ffff000 bytes maximum and could
write less if interrupted by a signal; when writing to Windows consoles, it’s
limited to 32767 bytes to avoid the "not enough space" error). This can lead to
silent loss of data, both when using sys.std{out,err}.buffer (which may in fact
not be a buffered stream) and when using the text streams sys.std{out,err}
(I’ve created a CPython bug report for that:
https://bugs.python.org/issue41221).

Python may fix the problem at some point. For now, we implement our own wrapper
for procutil.std{out,err} that calls the raw stream’s write() method until all
bytes have been written. We don’t use sys.std{out,err} for larger writes, so I
think it’s not worth the effort to patch them.

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.

.. note::

  Patterns specified in ``.hgignore`` are not rooted.
  Please see :hg:`help hgignore` for details.

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, and when the path points to a directory, it is matched
recursively. To match all files in a directory non-recursively (not including
any files in subdirectories), ``rootfilesin:`` can be used, specifying an
absolute path (relative to the 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``. ``rootglob:`` can be used
instead of ``glob:`` for a glob that is rooted at the root of the
repository.

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.

To read name patterns from a file, use ``listfile:`` or ``listfile0:``.
The latter expects null delimited patterns while the former expects line
feeds. Each string read from the file is itself treated as a file
pattern.

To read a set of patterns from a file, use ``include:`` or ``subinclude:``.
``include:`` will use all the patterns from the given file and treat them as if
they had been passed in manually.  ``subinclude:`` will only apply the patterns
against files that are under the subinclude file's directory. See :hg:`help
hgignore` for details on the format of these files.

All patterns, except for ``glob:`` specified in command line (not for
``-I`` or ``-X`` options), can match also against directories: files
under matched directories are treated as matched.
For ``-I`` and ``-X`` options, ``glob:`` will match directories recursively.

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"
  rootfilesin:foo/bar the files in a directory called foo/bar, but not any files
                      in its subdirectories and not a file bar in directory foo

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/*          any file in directory foo
  foo/**         any file in directory foo plus all its subdirectories,
                 recursively
  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.
  rootglob:*.c   any name ending in ".c" in the root of the repository

Regexp examples::

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

File examples::

  listfile:list.txt  read list from list.txt with one file pattern per line
  listfile0:list.txt read list from list.txt with null byte delimiters

See also :hg:`help filesets`.

Include examples::

  include:path/to/mypatternfile    reads patterns to be applied to all paths
  subinclude:path/to/subignorefile reads patterns specifically for paths in the
                                   subdirectory