Parallel SSH with Custom Parameters to Each Host

Question

There are plenty of threads and documentation about parallel ssh, but I can't find anything on passing custom parameters to each host. Using pssh as an example, the hosts file is defined as:

111.111.111.111
222.222.222.222

However, I want to pass custom parameters to each host via a shell script, like this:

111.111.111.111 param1a param1b ...
222.222.222.222 param2a param2b ...

Or, better, the hosts and parameters would be split between 2 files.

Because this isn't common, is this misuse of parallel ssh? Should I just create many ssh processes from my script? How should I approach this?

Answer 1

You could use GNU parallel .

Suppose you have a file argfile :

111.111.111.111 param1a param1b ...
222.222.222.222 param2a param2b ...

Then running

parallel --colsep ' ' ssh {1} prog {2} {3} ... :::: argfile

Would run prog on each host with the corresponding parameters. It is important that the number of parameters be the same for each host.

Answer 2

Here is a solution that you can use, after tailoring it to suit your needs:

#!/bin/bash
#filename: example.sh
#usage: ./example.sh <par1> <par2> <par3> ... <par6>

#set your ip addresses
$traf1=1.1.1.1
$traf2=2.2.2.2
$traf3=3.3.3.3

#set some custom parameters for your scripts and use them as you wish.
#In this example, I use the first 6 command line parameters passed when run the example.sh


ssh -T $traf1 -l username "/export/home/path/to/script.sh $1  $2" 1>traf1.txt 2>/dev/null &
echo "Fetching data from traffic server 2..."
ssh -T $traf2 -l username "/export/home/path/to/script.sh $3  $4" 1> traf2.txt 2>/dev/null &
echo "Fetching data from traffic server 3..."
ssh -T $traf3 -l username "/export/home/path/to/script.sh $5  $6" 1> traf3.txt 2>/dev/null &

#your application will block on this line, and will only continue if all 
#3 remotely executed scripts will complete
wait

Keep in mind that the above requires that you setup passwordless login between the machines, otherwise the solution will break to request for password input.

Answer 3

If you can use Perl:

use Net::OpenSSH::Parallel;
use Data::Dumper;

my $pssh = Net::OpenSSH::Parallel->new;

$pssh->add_host('111.111.111.111');
$pssh->add_host('222.222.222.222');

$pssh->push('111.111.111.111', $cmd, $param11, $param12);
$pssh->push('222.222.222.222', $cmd, $param21, $param22);

$pssh->run;

if (my %errors = $ssh->get_errors) {
  print STDERR "ssh errors:\n", Dumper \%errors;
}