Use an inline thread: 

use threads;

...

my $pid :shared;
my $tid = async{
    ## Removed 'my' below. Thanks Jettero.
    $pid = system("ssh root@ip ./sleepwake (args) &"); 
    $pid = 0;
    return $?;
};

...

## kill 2, $pid if $pid;

...

unless( $pid ) 
    my $result = $tid->join;
    ## do something;
}

...

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Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.
"Too many [] have been sedated by an oppressive environment of political correctness and risk aversion."

In reply to Re: Remotely Executing a background command by BrowserUk
in thread Remotely Executing a background command by NolanPL

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