termination of system command

[Anonymous Monk]

Hi Monks,
how to terminate command given specific time
if you see my code i can't come to second line untill kill the vmstat command

@val = `vmstat 10`;
foreach $_ (@val) {print "$_\n";}

can any body help me out on this

[Fletch]

In general one can use alarm (see also perlipc) to arrange for a signal to be delivered after a specified delay.

However in this specific case most implementations of vmstat should also take a count argument as well as a delay; start it with (say) vmstat 10 3 and you should only wait 20 seconds for 3 measurements (the first is immediate so you only get 2 delay periods).

[svenXY]

Hi,
you can also open it with '-|' (pipe from vmstat) and then use a while-loop as shown below:


#!/usr/bin/perl
use strict;
use warnings;

open(STAT, '-|', 'vmstat 2') or die "Could not open pipe: $!";

my $count; # not necessary, just for demonstration

while (<STAT>){
        last if $count++ > 5; # we don't want more than 5 lines of out
+put
        print $_, "\n";
}

print "...done\n";


Regards,
svenXY

[kyle]

Fletch is right about vmstat, but for an earlier discussion of interrupting backticks, see How to timeout if a call to an external program takes too long

[tcf03]

This does not answer your question directly, but why reinvent a wheel here? vmstat will stop itself using it like vmstat delay count. Using the following vmstat will stop collecting after 10 iterations at 10 second intervals.

@val = `vmstat 10 10`;



update - system or IPC::Run3 may serve you better.