Executing a tcpstat command and performing operations on its output simultaneously

Question

I am trying to run a tcpstat command that gives the output about number of icmp requests being received. and at the same time i need to check the count so that if it exceeds some threshold, a message should be displayed.

i tried out something like this

#!/usr/bin/perl

my @count= system "tcpstat -i eth1 -f icmp[0]==8 -o %C";

my $i=0;
while ($i<1000)
{
print "count of packets is :".$count[$i]."\n";
$i=$i+1;
if($count[$i]>50)
{   
print "thats a lot of pings";
}
}

but it doesn't seem to work because.. the execution of the command doesn't end without an user interrupt...

is it possible to do that? running the command and simultaneously performing operations over its output?

Answer 1

Run your tcpstat command in shell and pipe the output to your perl script.

tcpstat -i eth1 -f icmp[0]==8 -o %C  |  perl script.pl

In this way, you should expect your input from <STDIN> and remove the system call in perl, of course.