In the following, '(.*)' consumes the rest of the string as expected: 
$_ = "a b=c";
/(a)(.*)(?:b=(\w))?/;

printf "\$2 is [%s]\n", defined $2 ? $2 : "undefined";
printf "\$3 is [%s]\n", defined $3 ? $3 : "undefined";

[download]
prints 
$2 is [ b=c]
$3 is [undefined]

[download]
 I thought that using '(.*?)' would match up to 'b' then allow the optional '(?:b=(\w))?' to match, but this doesn't seem to be the case. Since they are both optional I guess it doesn't work. How can I consume everything up to a potential (?:b=(\w))? and still get (?:b=(\w))? to match? 
$_ = "a b=c";
/(a)(.*?)(?:b=(\w))?/;

printf "\$2 is [%s]\n", defined $2 ? $2 : "undefined";
printf "\$3 is [%s]\n", defined $3 ? $3 : "undefined";

[download]
prints 
$2 is []
$3 is [undefined]

[download]

In reply to RE greediness by Danny

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.