#!/usr/bin/perl
use warnings;
use strict;
use IPC::Open3;

my $pid = open3(\*WRITE, \*READ, 0, "/usr/sbin/tcpdump -i wlan0 ");
            #if \*ERROR is 0 (false), STDERR is sent to STDOUT 

print "pid $pid\n";

while(1){

select(undef,undef,undef,.01);  # small delay

 if( sysread \*READ,$output,1024 ){
     print "$output\n";
 }else{ print "finished\n"; exit; }

}
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