Why would you need this: 
  $s =~ s/^[ \t]+//mg;   # remove leading whitespace from each line
  $s =~ s/^\s+//;        # remove leading whitespace

[download]
when the second line will do everything that the firstline is doing?
Remember that $s is a multi-line string. So the regex mg modifier in the first regex above ensures that each line in the multi-line string has leading spaces and tabs removed from it.

The second regex, OTOH, does not have any modifiers, so it does not apply to every line in the multi-line string; instead, it trims leading whitespace (this time, including newlines) from the front of the multiline string -- trimming multiple blank lines from the front of a multi-line string, for example.

In reply to Re^2: Removing multiple trailing comment lines from a string by eyepopslikeamosquito
in thread Removing multiple trailing comment lines from a string by eyepopslikeamosquito

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.