Perl expect output of executed command

Question

i wrote a little script which executes the ls command. Now I want to store the output of that command in a variable to work with it in the further perl script. Unfortunately I cannot grab the output from the ls command.

my ($core) = "servername";
    my $tel_con = "ssh ".$core. " -l $user";

    $ssh = Expect->spawn("$tel_con");
    $ssh->log_stdout(1);

    unless ( $ssh->expect( 5, -re => '$' ) ) {
            return "Never connected " . $ssh->exp_error() . "\n";
    }
    sleep 1;
    $ssh->send_slow(0, "ls -l\r");
    $ssh->clear_accum();
    my $str = $ssh->exp_after();
    print "STR = '$str'\n";

Maybe you can give me some help please?

salva · Accepted Answer · 2011-10-26 08:11:51Z

1

use Net::OpenSSH;

my $ssh = Net::OpenSSH->new($core, user => $user);
$ssh->error and die $ssh->error;

my $output = $ssh->capture('ls -l');

print "command output:\n$output\n\n";

answered Oct 26, 2011 at 8:11

salva

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Thorsten Niehues · Accepted Answer · 2012-09-05 14:06:18Z

1

In case you can not or don't want to use Net::OpenSSH you may do:

my @output = $exp->expect(5);
print 'OUT: '.$output[3].'END';

To get the whole output (including the used command, return string, console information)

answered Sep 5, 2012 at 14:06

Thorsten Niehues

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Hachi · Accepted Answer · 2011-10-24 14:42:14Z

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you could call expect in a seperate process and grab the output via qx or open a pipe

answered Oct 24, 2011 at 14:42

Hachi

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3 Comments

JohnDoe Over a year ago

Maybe you can give me a short example?

Hachi Over a year ago

Example: copy the expect-code in an extra file ssh.pl and do a my $ls_content = qx(ssh.pl $args);

JohnDoe Over a year ago

Sorry but I'm really new to expect. So I call the upper posted script with ls_content = qx(ssh.pl) ?

Katerberg · Accepted Answer · 2011-10-24 14:44:28Z

0

What is send_slow? Depending on how this command sends the ls command, the output can be received in different ways.

Most probably, the error output of the command is stored in the $? variable, possibly byte-shifted.

answered Oct 24, 2011 at 14:44

Katerberg

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jtv4k · Accepted Answer · 2011-10-24 21:07:48Z

0

It seems that Expect will redirect everything to STDOUT and log it internally. Since you enabled output with $ssh->log_stdout(1), you should be able to get the results of ls -l directly from STDOUT (maybe by redirecting standard out to a variable). You can also see try grab the data from the internal logging. Just make sure to grab the output before doing clear_accum().

From CPAN: $object->send_slow($delay, @strings);

... After each character $object will be checked to determine whether or not it has any new data ready and if so update the accumulator for future expect() calls and print the output to STDOUT and @listen_group if log_stdout and log_group are appropriately set.

answered Oct 24, 2011 at 21:07

jtv4k

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1 Comment

JohnDoe Over a year ago

Thanks. Can you give me a little code example please? I tried the following: $telnet = Expect->spawn("$tel_con"); $telnet->debug(3); $telnet->exp_internal(1); $telnet->log_stdout(0); $telnet->set_group($ret); $telnet->log_group(1); $telnet->expect(0); unless ( $telnet->expect( 5, -re => '$' ) ) { return "Never connected" . $telnet->exp_error() . "\n"; } sleep 1; $telnet->send_slow(0, "ls -l\r"); my $str = $telnet->before(); print "STR = '$str'\n"; print "ret = $ret\n";

PinkElephantsOnParade · Accepted Answer · 2012-06-08 15:29:31Z

0

Layman's terms?

I must obligatorily post this link - I still go there from time-to-time, it is the most layman-y explanation I've ever found of all things regex:

http://www.anaesthetist.com/mnm/perl/Findex.htm

answered Jun 8, 2012 at 15:29

PinkElephantsOnParade

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