the expression $var =~ /regex/ returns a true or false value, not the captured value. The special variable $1 contains the value you captured in the parentheses, so you should use something along the following lines: 

my $build;
if ($vadata =~ /=(\d+)\s*$/) {
    $build = $1;
}

[download]
and use $build only if it's not null.

UPDATE: actually the OP was matching in list context, not scalar context, so a messed up answer. Please ignore and see above and below for a more enlightened discussion...

"Principle of Least Astonishment: Any language that doesn’t occasionally surprise the novice will pay for it by continually surprising the expert..

In reply to Re^2: Use of uninitialized value when using regex by Erez
in thread Use of uninitialized value when using regex by PerlScholar

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