Expect_FAQ(3pm)

Expect.pm - Frequently Asked Questions This is a growing collection of things that might help. Please send you questions that are not answered here to [email protected]
Can I use this module with ActivePerl on Windows? I don't know. Probably not. There is no native support for ptys available under Windows. On the other hand, Cygwin (http://sourceware.cygnus.com) promises to provide POSIX ptys for NT, so it should be possible to run Expect.pm under Cygwin. The Tcl/Expect homepage at http://expect.nist.gov gives two links to porting projects that might be of interest (one being DejaGnu on Cygwin).
How can I find out what Expect is doing? If you set

  $Expect::Exp_Internal = 1;

Expect will tell you very verbosely what it is receiving and sending, what matching it is trying and what it found. You can do this on a per-command base with

  $exp->exp_internal(1);

You can also set

  $Expect::Debug = 1;

which gives you even more output.
I am seeing the output of the command I spawned. Can I turn that off? Yes, just set

  $Expect::Log_Stdout = 0;

to globally disable it or

   $exp->log_stdout(0);

for just that command. 'log_user' is provided as an alias so Tcl/Expect user get a DWIM experience... :-)
I want to log the whole session to a file. Use

  $exp->log_file("filename");

or

  $exp->log_file($filehandle);

to start logging. Note that the log is appended by default, but you can specify an optional mode "w" to truncate the logfile:

  $exp->log_file("filename", "w");

To stop logging, just call it with a false argument:

  $exp->log_file(undef);

How can I turn off multi-line matching for my regexps? To globally unset multi-line matching for all regexps:

  $Expect::Multiline_Matching = 0;

You can do that on a per-regexp basis by stating "(?-m)" inside the regexp (you need perl5.00503 or later for that).
How can I expect on multiple spawned commands? You can use the -i parameter to specify a single object or a list of Expect objects. All following patterns will be evaluated against that list. You can specify -i multiple times to create groups of objects and patterns to match against within the same expect statement. This works just like in Tcl/Expect. See the source example below.
I seem to have problems with ptys! [You're on HP-UX, right?] Well, pty handling is really a black magic, as it is extremely system dependend. I'm thinking about stealing the pty stuff from Tcl/Expect (Hi, Don!), as that code looks much more mature than what gets done in Expect and/or IO::[TP]ty. Please be patient, this may take a while...
How to automate login

  $obj->expect($timeout,
               [
                qr'login: $',
                sub {
                  my $fh = shift;
                  print $fh "$username\r"; exp_continue;
                }
               ],
               [
                'Password: $',
                sub {
                  my $fh = shift;
                  print $fh "$password\r"; exp_continue;
                }
               ],
               [
                timeout =>
                sub {
                  die "No login.\n";
                }
               ],
               '-re', qr'[#>:] $', #' wait for shell prompt, then exit expect
              );

How to expect on multiple spawned commands

  foreach my $cmd (@list_of_commands) {
    push @commands, new Expect $cmd;
  }

  expect($timeout,
         '-i', \@commands,
         [
          qr"pattern",          # find this pattern in output of all commands
          sub {
            my $obj = shift;    # object that matched
            print $obj "something\r";
            exp_continue;       # we don't want to terminate the expect call
          }
         ],
         '-i', $some_other_command,
         [
          "some other pattern",
          sub {
            my ($obj, $parmref) = @_;
            # ...

            # now we exit the expect command
          },
          \$parm
         ],
        );