Hello, Monks, I am trying to make the expect interact with "units" program. But it does not want to match anything, except qr/.*/ and the $exp->before prints nothing. If you want to test, the units can be obtained from http://www.gnu.org/software/units/

use Expect;

$Expect::Debug = 3;    # verbose debug output
$Expect::Log_Stdout = 1;  # show chatter for debugging
$Expect::Exp_Internal =1;
  my $exp = Expect->spawn("units")
    or die "Cannot spawn unit: $!\n";

$exp->log_stdout(1);
$exp->expect(15,
               [ qr/you have/i => sub { my $exp = shift;
                                       print "you have";
                                     $exp->send("2 km");
                                     exp_continue; } ],
               [ qr/you want/i , sub { my $exp = shift;
                                       print "you want"; 
                                       $exp->send("m");
                                       exp_continue; }],
                   [ 'eof', sub { my $exp = shift; print "eof"; print 
+$exp->before(); } ],
                   [ qr/.*/, sub { my $exp = shift;
                                   print $exp->error;
                                   print $exp->before();
                        } ]
              );
[download]

The units executed in the terminal will print these

user@dell:~> units
2526 units, 72 prefixes, 56 nonlinear units

You have:
[download]

In the log it shows this

spawn id(20): Does `'
match:
  pattern #1: -re `(?^i:you have)'? No.
  pattern #2: -re `(?^i:you want)'? No.
  pattern #3: -eof `'? No.
  pattern #4: -re `(?^:.*)'? YES!!
    Before match string: `'
    Match string: `'
    After match string: `'
    Matchlist: ()
Calling hook CODE(0x7fd8217449c0)...
Returning from expect successfully.
  spawn id(20): accumulator: `'
Closing spawn id(20).
[download]

Before match string: `' Why does it show `' ? what is that string ? And what is wrong with the code ? Thanks

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