```{index} single: Filter::exec ``` # Filter::exec exec source filter ## SYNOPSIS ```perl use Filter::exec qw(command parameters) ; ``` ## DESCRIPTION This filter pipes the current source file through the program which corresponds to the `command` parameter. As with all source filters its scope is limited to the current source file only. Every file you want to be processed by the filter must have a ```perl use Filter::exec qw(command ) ; ``` near the top. Here is an example script which uses the filter: ```perl use Filter::exec qw(tr XYZ PQR) ; $a = 1 ; print "XYZ a = $a\n" ; ``` And here is what it will output: ```text PQR = 1 ``` ## WARNING You should be _very_ careful when using this filter. Because of the way the filter is implemented it is possible to end up with deadlock. Be especially careful when stacking multiple instances of the filter in a single source file. ## AUTHOR Paul Marquess ## DATE 11th December 1995.