Check out Fcntl.
from the man page(unfortunately the perldoc page doesn't go into enough detail): 
F_SETFL  Set  the descriptor's flags to the value specified by arg.  
                Only O_APPEND, O_NONBLOCK and O_ASYNC
                may be set; the other flags are unaffected.

[download]


There is also some suggestions here (you can find with search)
  • FAQ - How do I open a file without blocking?
  • non-blocking accept


    • I will also recommend:
  • On asking for help
  • How to ReadTheFineManual

    • know thy FAQ - search is your friend

    grep
    grep> chown linux:users /world

    In reply to Re: non-blocking reading by grep
    in thread non-blocking reading by Anonymous Monk

    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.