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You can't rely on the commands making it through in one piece.

Furthermore, there are recommendations to avoid using buffered IO (<SOCK>, read, eof, getline, getlines) in the docs. sysread is not buffered.

  • For each socket with data available (as returned by select),
    • Read (using sysread) from the socket.
    • If sysread returned undef,
      • Remove socket from the select object.
      • Handle error socket.
    • If sysread returned zero,
      • Remove socket from the select object.
      • Handle closed socket.
    • Append to the socket's buffer the data that was read from the socket.
    • While the buffer has a full line/command in it,
      • Extract the line/command from the buffer (leaving the rest in the buffer).
      • Process the extracted line/command.
my ($r_ready, $w_ready) = IO::Select::select($r_sel, $w_sel); foreach my $sock (@$r_ready) { # Create alias to the appropriate buffer. our $buf; local *buf = \$in_bufs{$sock}; my $rv = sysread($sock, $buf, 4096, length($buf)); # Read error. if (not defined $rv) { $r_sel->remove($sock); # ... Handle error socket ... next; } # Socket EOF if (not $rv) { $r_sel->remove($sock); # ... Handle closed socket ... next; } for (;;) { # Search for a complete command. my $pos = index($buf, "\x0A"); last if $pos < 0; my $cmd = substr($buf, 0, $pos+1, ''); # ... process $cmd ... } } foreach my $sock (@$w_ready) { # ... }

Update: Added code.
Update: Bug fix to handle the case where multiple commands in the buffer.

In reply to Re: IO::Handle read error description? by ikegami
in thread IO::Handle read error description? by Marcello

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