# Prebuild the RE patterns for efficiency's sake.
my @patterns = ( qr(pattern1),
                 qr(pattern2),
                 qr(pattern3),
                 qr(pattern_n) );
# Use paragraph mode in case your pattern spans multiple lines.
# This may need to be combined with the /s switch on your
# regexp.  Since we don't know what the patterns look like,
# I'll use this mechanism to be on the safe side.
{    
    local $/ = "\n\n";
    while ( my $paragraph = <FILE> ) {
        $paragraph =~ s/$_/pagingRAC/gs foreach @patterns;
        print TEMP_OUT $paragraph;    
    }
}