Then I assume the match doesn't span more than one line?

my @match;
while (<>)) {
   my @caps = /pat/
      or next;
   @match = @caps;
}

if (@match) {
    print("Captured @match\n");
} else {
    die("No match\n");
}
[download]

or

my $match;
while (<>)) {
   $match = $_ if /pat/;
}

if (defined($match)) {
    print("Matched $match");
} else {
    die("No match\n");
}
[download]

All this guessing is leading to suboptimal solutions and wated work. If this is still not good, please provide more info about your problem.