When a client's INET socket is closed, the socket on the server's end will show up as 'ready', but the next read from it will read 0 bytes, or in perl's case as 'undef' if you read it with <$socket>. In the case of 'non-blocking' io, if you get a positive can_read() and read length of 0, then the socket was closed on the other end. 

@reads = $select->can_read() ;
for( @reads ) {
   $data = <$_> ;
   if( $data == undef && $! != EWOULDBLOCK ) {
       # socket closed from the other end
   }
}

[download]
Reference: Unix Network Programming 2nd Ed Vol 1 page 166-167, by W. Richard Stevens

In reply to Re: IO::Select->can_read isn't recognising closed INET connections by ptkdb
in thread IO::Select->can_read isn't recognising closed INET connections 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.