Well, you will have to read the documentation for your particular version of sudo and find out why it is failing, which one is the "invalid argument".

Regarding the Perl part, sudo does not expect the subcommand and its arguments passed combined into a single argument. Try as follows: 

$ssh->capture({ tty => 1,
                stdin_data => "$password\n" },
              'sudo', '-Sk', '-p', '', '--', 'su', '-lc', 'ls', imail'
+);

[download]

In reply to Re^9: Problem using Net::OpenSSH->capture to su to another user by salva
in thread Problem using Net::OpenSSH->capture to su to another user by tim.culhane

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