There are a number of builtin ways to do this, partucularly if the regex is stored in perl syntax.

1. do FILE;
2. open FL, $fname; $re = <FL>; close FL;
3. require FILE
4. use MODULE

Each listed way has it's own conventions for getting a value out. The elegant way if to make the file a module:

package VIR;
our $vir = qr/My\s+[Rr]egex/;
1;
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Usage:

#!/usr/bin/perl -w
use strict;
use lib '/location/of/lib/';
use VIR;

$_="My regexen";
print "found\n" if m/$VIR::vir/;
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Each listed way has it's own conventions for getting a value out.

After Compline,
Zaxo