Re: [Expectperl-discuss] ssh works from console but not once daemonized

[expect <ex...@ih...>]

On Sun, 14 Sep 2003 16:27:52 -0500
"Chris Muth" <mut...@mc...> wrote:

> Hi,
> 
> I am working on a script that daemonizes and then uses
> ssh to login/operate/logout of a remote machine.
> 
> The code works perfectly when it is not demonized, (with the demonization
> code commented out).  The script will run and partially work if the
> code (the lines indicated below) is left in,-- it will fork, detach, and
> sleep but fail to get the command prompt on the remote machine.
> I have it log to a file (LOG_FILE), because when it is daemonized I cannot
> see the output.
> 
> The only thing I can think of is that ssh must do something to the
> terminal/console that works
> when I run it manually on the console, but when the program
> is daemonized, ssh cannot do whatever it is trying to do and fails.
> 
> The segment below fails saying "never got command prompt".  This means that
> it got the password prompt from the remote machine
> and sent the password, but never got the command prompt after that.
> 
> I don't think this is an expect problem, I think that it is a problem with
> how ssh and expect work together.
> My guess is that ssh is not intentionally failing, but it is trying to do
> something that does not work with the terminal that expect uses.
> 
> I have even tried "ssh -l root" to specify the username, "ssh -T" so ssh
> won't allocate a pseudo-tty, and not setting the pty to raw; all to no
> avail.
> 
> Does anyone have any ideas?
> Below is the code segment.
> 
> Thanks,
> -Chris Muth
> 
> 
> #!/usr/bin/perl5.8 -w
> 
> #prompt user for host to login to, and password
> print"host: ";$host=<STDIN>;chomp$host;
> print"pass: ";$pass=<STDIN>;chomp$pass;
> 
> use Expect;

$Expect::Debug = 1;

> use POSIX;
> 
> #  Comment out daemonizing code starting here
> #######################################
> $pid = fork();
> exit 0 if ($pid);
> 
> POSIX::setsid();
> close STDIN;

I commented this

#close STDIN;


> close STDOUT;
> close STDERR;
> 
> sleep 5;
> #######################################
> # comment out daemonizing code ending here
> 
> open (LOG_FILE, "> output"); # open log file
> 
> $exp = new Expect;
> $exp->raw_pty(1);
> 
> # login to the remote host
> #$exp->spawn("/usr/local/bin/ssh",'-T',"$host");  # Even tried ssh -T
> $exp->spawn("/usr/local/bin/ssh","$host");

and had to do this (probably not pertinent to your problem)

$exp->spawn("/usr/local/bin/ssh","usernameonremotehost\@$host");

And it worked.  If it's not suitable as a solution it should provide
the clue.

> 
> # wait for Password: prompt
> $retval = $exp->expect(30,'-re','word:\s$');
> if (!defined $retval){
>    print LOG_FILE "Never got password prompt\n"; flush LOG_FILE;
> } else {
>    $exp->send("$pass\n");
>    #($retval,undef,$retstr,undef,undef) = $exp->expect(30,'stdin: is not a tty'); # for ssh -T
>    ($retval,undef,$retstr,undef,undef) = $exp->expect(30,'# ');
> 
>    # do something on the remote machine, test results
>    if (!defined $retval){
>       print LOG_FILE "Never got command prompt\n"; flush LOG_FILE;
>    } else {
>       print LOG_FILE "\"$retstr\"\n"; flush LOG_FILE;
>       $exp->send("echo Hello World\n");
>       $exp->expect(5,'This will make expect sleep for 5 seconds');
>       $exp->send("logout\n");
>       print LOG_FILE "It worked\n"; flush LOG_FILE;
>    }
> }
> $exp->hard_close();
> print LOG_FILE "\n"; flush LOG_FILE;
> close LOG_FILE;
> exit 0;
> 
> 
> 
> 
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