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Expect-1.11
River stage three • 33 direct dependents • 530 total dependents
/ Expect.pm

NAME

Expect.pm - Frequently Asked Questions

SYNOPSIS

This is a growing collection of things that might help. Please send you questions that are not answered here to RGiersig@cpan.org

DESCRIPTION

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...

Source Examples

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
	 ],
	);