termination of system command

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

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Re: termination of system command by Fletch (Bishop) on Feb 11, 2008 at 15:06 UTC
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). The cake is a lie. The cake is a lie. The cake is a lie.	[reply]
Re: termination of system command by svenXY (Deacon) on Feb 11, 2008 at 15:21 UTC
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";` [download] Regards, svenXY	[reply] [d/l] [select]
Re: termination of system command by kyle (Abbot) on Feb 11, 2008 at 15:56 UTC
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	[reply] [d/l]
Re: termination of system command by tcf03 (Deacon) on Feb 11, 2008 at 16:27 UTC
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`; [download] update - system or IPC::Run3 may serve you better. Ted -- "That which we persist in doing becomes easier, not that the task itself has become easier, but that our ability to perform it has improved." --Ralph Waldo Emerson	[reply] [d/l]