<FH> reads until the end of the line. You want to read until the end of available data. You need to use sysread.

Simplisticly, sysread($handle, my $message, 1024); will work.

Realisticly, you need something adapted from that which I posted earlier. Give me a couple of minutes, and I will post the necessary code.

Update: I've just found out that -s will return the number of bytes available (on FreeBSD). So all you need is the following: 

sysread($handle, my $message, -s $handle);

[download]

You will need to split the lines apart, but that shouldn't be a problem.

Update: If you wanted to be super safe — i.e. if you don't want to reply on your OS's implementation details — you could use the following. As a bonus, it still supports multiple child handles. 

my %buf;

while (my @handles = $ios->can_read(0)) {
   foreach my $handle (@handles) {
      $buf{$handle} ||= { buf => '', offset => 0 };

      # Aliases to improve readability through conciseness.
      our $buf;    local *buf    = \($buf{$handle}{buf   });
      our $offset; local *offset = \($buf{$handle}{offset});

     #my $len = sysread($handle, $buf, -s $handle, $offset);#Portable?
      my $len = sysread($handle, $buf, 1024,       $offset);

      die("Unable to read from pipe: $!\n")
         if not defined $len;

      if (not $len) {
         $ios->remove($handle);
         next;
      }

      $offset += $len;

      for (;;) {
         my $pos = index($buf, "\x0A");

         last if not ++$pos;

         my $message = substr($buf, 0, $pos);
         $buf = substr($buf, $pos);
         $offset -= $pos;

         $message =~ s/\x0A$/\n/;  # For Macs.

         print "Read message: ".$message;
      }
   }
}

foreach (keys %buf) {
   die("Unable to read from pipe: Premature end of file\n")
      if $buf{$_}{offset};
}

[download]

In reply to Re: Reading from a pipe line by line by ikegami
in thread Reading from a pipe line by line by Marcello

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.