# PerlIO::mmap - man - phpman

## NAME
    [PerlIO::mmap](https://www.chedong.com/phpMan.php/perldoc/PerlIO%3A%3Ammap/markdown) - Memory mapped IO

## SYNOPSIS
     open my $fh, '<:mmap', $filename;

## DESCRIPTION
    This layer does "read" and "write" operations by mmap()ing the file if possible, but falls back
    to the default behavior if not.

## IMPLEMENTATION NOTE
    "[PerlIO::mmap](https://www.chedong.com/phpMan.php/perldoc/PerlIO%3A%3Ammap/markdown)" only exists to use XSLoader to load C code that provides support for using memory
    mapped IO. One does not need to explicitly "use [PerlIO::mmap](https://www.chedong.com/phpMan.php/perldoc/PerlIO%3A%3Ammap/markdown);".