Okay, I can write two sample programs to illustrate my question.

p1.pl 
#!/usr/bin/perl

use strict;
use warnings;

$|=1;

my $p2 = "/tmp/p2.pl";

open(P2,"$p2 |") || die "P2: $p2 - $!\n";
while(<P2>) {
   print;
}

[download]
p2.pl 
#!/usr/bin/perl

use strict;
use warnings;
$|=1;

my $i;

for $i (1..10) {
   print ".";
   sleep 1;
}
print "\n";

[download]
The output of p2.pl is 1 dot every second for 10 seconds but the output of p1.p1 is 10 dots after 10 seconds. Thanks.

In reply to Re^2: Nested line buffered output by Anonymous Monk
in thread Nested line buffered output by Anonymous Monk

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