If have executed the following code with input redirected to dev/null

my @cmds = ("sh int des");                              # define comma
+nds.
my @hosts = ("XXX", "XXX");       # define hosts.
my @params = (\@cmds, \@hosts);                         # construct pa
+rameter array (currenlty mandatory for execution in a sub process).
my $job = new Job(\&exec_on_each, \@params);            # define job
Dispatcher::query_job($job);                            # add jobs to 
+the dispatchers queue.
my @out = Dispatcher::execute_jobs();                   # execute all 
+jobs and retieve the result.
print Tools::to_string(\@out);                          # print the re
+sult in the console.
[download]

You launch ssh without an absolute path name.

Have you made sure that $ENV{PATH} is the same when run via the web server as when run via the console?

Have you inspected the error message you get? $exp->error() might provide more information...

Thank you so much for your assistance! The subprocess that starts the ssh connection set the $ENV{"PATH"} = "/usr/bin"; (required by expect because of possible tainted return) The $exp->error() returns -1 after each interaction. Unfortuantly i'm very limited on the system i use, and i do not have access to Net::SSH::Any or IPC.

# assigns a job to a worker process.
# :param 0:     job.
# :return:
sub assign_job {
    my ($job) = @_;
    my $pid = open my $pipe => "-|";                    # create worke
+r process and connect it using a pipe.
    Debug::dlog("spawned process : $pid");
    die "Failed to fork: $!" unless defined $pid;       # check that c
+reation was successfull.
    my $routine = $job->get_routine();                  # get routine 
+to execute.
    my $params = $job->get_params();                    # get paramete
+rs to pass.
    unless ($pid) {                                     # the followin
+g code is only executed in the worker process:
        $ENV{"PATH"} = "/usr/bin";                      # delete conte
+xt.
        my $return = $routine->(@$params);              # execute rout
+ine.
        my $dump = Dumper($return);                     # serialize th
+e returned object.
        print($dump);                                   # print data s
+tring to pipe.
        Debug::dlog("process ".$$." dumped ".length($dump)." chars");
        exit;                                           # terminate pr
+ocess.
    } else {                                            # only in pare
+nt process:
        my $worker = new Worker($pipe, $pid);           # construct ne
+w worker object.
        push(@Dispatcher::workers, $worker);            # save worker 
+object.
    }
}
[download]

Thanks for your reply! I think i understand the issue now. When there is no terminal, there can't be any interaction. Unfortunately i can not establish a passwordless connection (for reasons i would like to ommit). I will test as you advised. I just wonder, even if i connect with a key, will i be able to retrieve the devices response without any terminal? Is there another library for perl, that works without a terminal?

Friendly Regards,

Phil

Personally, for interactive stuff, I would look at Net::SSH::Any or any of the modules that Net::SSH::Any uses. There you can conveniently send commands/input over a channel without needing Expect at all.

Alternatively, you could look at IPC::Run for opening a child process (in your case, the ssh connection) for reading and writing, but this goes close to reimplementing Expect yourself and won't solve the password issue.