I suspect that it's due to the fact that $output doesn't contain what you think it does, and the return ($1) is uninitialized.

Better to check for this condition (untested):

sub getToken {
    my $output = `curl -k -s -XPOST (URL) -dgrant_type=password -dclie
+nt_id=(client ID) -dclient_secret=(client secret) -dusername=(usernam
+e) -dpassword=(password)`;   
    if ($output =~ /"access_token":"(.*)", "ex/g){
        return $1;
    }
    else {
        die "output not as expected...\n";
    }    
}

[download]

In reply to Re: why is this an uninitialized value? by stevieb
in thread why is this an uninitialized value? by jdorwin

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.