Hmm, no, I think you're confusing can_read with the routine that actually does the reading, you're confusing a scalar variable with an array, and I can't tell if you've turned buffering off on the $lsn file handle, but I'm guessing not.

Your code: 

$results = $sel->can_read(0);# or die "cant read";
#print Dumper @results;

print "\n****Outside if****";
print "results== $results\n";

[download]

Ping code: 

if ( $select -> can_read( 0 ) ) {
    my $remote = recv ( $pinger, $buff, SIZE, RCV_FLAGS );
    if ( $debug ) { 
         print "result from ", unpack("C*",$remote), ":",
         unpack ( "C*", $target_addr), "\n"; 
    }

    # sometimes ICMP replies come from other devices, filter those out
    if ( $remote eq $target_addr ) {
        $received++;
    }
}

[download]

So, you've, at best, got a boolean result from the can_read, but then you use that as if can_read returned an array of data from the wire, rather than use a recv() call to actually read the data properly.

I'm also betting that you're Suffering from Buffering, which means unless you've tested by sending tons of stuff, the buffer never filled up, and it *LOOKS* like you've not received anything.

-Scott

In reply to Re^3: Checking if a socket has some data to read by 5mi11er
in thread Checking if a socket has some data to read by perlgsm

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.