Re: threads, forks and SSH

You can use Net::OpenSSH::Parallel for that:

use Net::OpenSSH::Parallel;

my @hosts = (...);

my $pssh = Net::OpenSSH::Parallel;

# register the list of hosts:
$pssh->add_host($_) for @hosts;

# declare the commands you want to run in every host:
$pssh->push('*', cmd => 'do.this');
$pssh->push('*', cmd => 'do.that');
$pssh->push('*',
            { stdout_file => '%HOST%.csv' }, # %HOST% is replaced by t
+he host name
            cmd => 'make.csv');

# let Net::OpenSSH::Parallel take care of everything:
$pssh->run;

# finally, collect the errors and the temporary CSV files.
for my $host (@hosts) {
  my $error = $pssh->get_error($host);
  if ($error) {
    print STDERR "Failed to generate CSV from host '$host': $error\n";
  }
  else {
    system cat => "$host.csv";
    unlink "$host.csv";
  }
}
[download]

update: code adjusted according to some of the comments by serf below.

Comment on Re: threads, forks and SSH Download Code

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Re^2: threads, forks and SSH by serf (Chaplain) on Dec 15, 2015 at 13:31 UTC
Meh about: `system 'cat $host.csv'; system 'rm $host.csv';` [download] You have open and print, you have unlink, and you have ways of checking that what you wanted to do worked correctly. Perl isn't a shell script. I would suggest that it's more reliable, more efficient, more cross-OS portable, and generally better practice to do these things natively in Perl than shelling out via system. I get given grief at my $JOB by "scripts" that people who don't know Perl have written in Perl which should be in Perl but are full of awk and sed and grep and wc pipes and other badness. These scripts spawn many more processes than they need to, use more memory, and end up doing knarly things like jamming up, failing silently or causing excessive IO over NFS etc, bringing down our systems. When we post code on perlmonks, people who don't know as much as we do will take what we've written without understanding it and use it thinking it's the right way to do it. I think we should try and be responsible and steer them in the right direction. /me dismounts soapbox	[reply] [d/l]
Re^3: threads, forks and SSH by ralph2014 (Initiate) on Dec 15, 2015 at 14:04 UTC
Morning again Monks! Thank you so much for the replies. This module sounds just what im looking for. Im not too bothered about things being a little dirty aslong as it gets it done quickly and I get decent output. I should add its a windows server 2003. ralph	[reply]
Re^4: threads, forks and SSH by salva (Canon) on Dec 15, 2015 at 14:15 UTC
Oops, then you can not use it: Net::OpenSSH does not work on Windows. Your best option there is to go for Net::SSH2 or Net::SSH::Perl, but IIRC, both have issues with threads.	[reply]
Re^5: threads, forks and SSH by ralph2014 (Initiate) on Dec 15, 2015 at 23:45 UTC
Re^6: threads, forks and SSH by dasgar (Priest) on Dec 16, 2015 at 05:29 UTC
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