Fifos + Pipes

Sascha2481 has asked for the wisdom of the Perl Monks concerning the following question:

Hello, i dont know where i can post my problem. I hope you can help me.

$|=1;
my $recv = 0; 
while(1) {
$recv++;
if($recv > 200) { 
print "<!-- //--> "; 
undef $recv;
}

open(FIFO,"<fifo"); 
my @read = <FIFO>;
close(FIFO);

foreach(@read) {
............
}

sleep 1; 
}
[download]

If i start this program it reads from a PIPE. But it waits so long till the program reads from a PIPE and THEN goes again trough the Loop. But i want that: Go trough loop , read from pipe , sleep 1 second and then start the loop again. I hope you can help me , sorry for my bad english.

Comment on Fifos + Pipes Download Code

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Re: Fifos + Pipes by jonadab (Parson) on Oct 02, 2003 at 13:22 UTC
If you want to get through that loop and actually get to any of the code below that reads from the fifo, you'll need a much faster processor, preferably a quantum computer. Otherwise, you might try putting code that reads from the pipe inside the loop, or something, or maybe `last if $recv > $somemaximumvalue`. update: but that won't work if you reset $recv to 0 before it reaches the max value. I think what you really want is to read a line inside the loop. If i start this program it reads from a PIPE. But it waits so long till the program reads from a PIPE and THEN goes again trough the Loop. No, you have that backwards. It's doing the reverse: going through the loop first before it opens the pipe. Since the loop never exits, the pipe is never read. `$;=sub{$/};@;=map{my($a,$b)=($_,$;);$;=sub{$a.$b->()}} split//,".rekcah lreP rehtona tsuJ";$\=$ ;->();print$/` [download]	[reply] [d/l] [select]
Re: Fifos + Pipes by Anonymous Monk on Oct 03, 2003 at 10:12 UTC
I think there is nothing to read in this "fifo". The process is waiting for a CR which is never arriving. For your tests use a textfile instead of "fifo". Use a string $read instead of a array @read. If this is unsuccessful use the debug-mode of the perl-interpreter. Good luck rolf	[reply]