# man > Filter::Util::Exec(3pm)

## NAME
    [Filter::Util::Exec](https://www.chedong.com/phpMan.php/perldoc/Filter%3A%3AUtil%3A%3AExec/markdown) - exec source filter

## SYNOPSIS
        use [Filter::Util::Exec](https://www.chedong.com/phpMan.php/perldoc/Filter%3A%3AUtil%3A%3AExec/markdown);

## DESCRIPTION
    This module is provides the interface to allow the creation of *Source Filters* which use a Unix
    coprocess.

    See [Filter::exec](https://www.chedong.com/phpMan.php/perldoc/Filter%3A%3Aexec/markdown), [Filter::cpp](https://www.chedong.com/phpMan.php/perldoc/Filter%3A%3Acpp/markdown) and [Filter::sh](https://www.chedong.com/phpMan.php/perldoc/Filter%3A%3Ash/markdown) for examples of the use of this module.

    Note that the size of the buffers is limited to 32-bit.

  filter_add()
    The function, "filter_add" installs a filter. It takes one parameter which should be a
    reference. The kind of reference used will dictate which of the two filter types will be used.

    If a CODE reference is used then a *closure filter* will be assumed.

    If a CODE reference is not used, a *method filter* will be assumed. In a *method filter*, the
    reference can be used to store context information. The reference will be *blessed* into the
    package by "filter_add".

    See [Filter::Util::Call](https://www.chedong.com/phpMan.php/perldoc/Filter%3A%3AUtil%3A%3ACall/markdown) for examples of using context information using both *method filters* and
    *closure filters*.

## AUTHOR
    Paul Marquess

## DATE
    11th December 1995.