example 1: blah (foobar) blah

example 2: blah (foo
all sorts of content on
lots of lines
of data 
bar) blah

##</code><code>##

my $regex_string = join '|', @list_patterns;

open( FILE, "<", $arg1 ) or die "$arg1: $!";
$_ = do { local $/; <FILE> };  # temporarily set $/ = undef to slurp file
close FILE;

if ( /($regex_string)/is ) {
    # got a match...
}

##</code><code>##

my $list_regex = qr/($regex_string)/is;
...
if ( /$list_regex/ ) {
...