http://www.perlmonks.org?node_id=58634
Description: If you have ever used Expect to execute commands on a remote system I am sure you have run into the problem of parsing the command output from the output of the Expect methods exp_before(), clear_accum(), etc... . If you send your command to this subroutine it will parse the output for you and return the command output as it would be returned from a backtick execution. Note: This subroutine uses a global Expect object variable which already has an established connection. The subroutine will not take commands that end in & .. for those commands just use $expect->print method. 
# Executes a command via a global expect object and
# returns the output of the command.
#
# Arguments:
#       1 - Command     <string variable containing the command string
+>
# Returns:
#       String variable cotaining the output of the specified command.
#

sub expect_execute($) {
        $expect->clear_accum();
        my $command = shift;
        my $x = '';
        my $temp = '';
        if ( $command =~ /;$/ ) {
                chop( $command );
        }
        print $expect "$command | sed 's/^/COMMAND_OUT: /g'; echo -n E
+ND_; echo EXPECT\n";
        $expect->expect( 300, -re => '^END_EXPECT' );
        my $result = $expect->exp_before();
        ( my @result ) = split( /\n/, $result );
        $result = '';
        foreach $x ( @result ) {
                $temp = $x;
                if ( chop( $temp ) eq "\r" ) {
                        chop( $x );
                }
                if ( $x =~ m/^COMMAND_OUT: / ) {
                        $temp = substr( $x, 13 );
                        $result = $result . $temp . "\n";
                }
        }
        return $result;
}
Replies are listed 'Best First'.
Re: Expect command output parser sub
by vishi (Beadle) on Jan 03, 2012 at 07:20 UTC

    This is brilliant!!!! Thank you so much for this.. I've been fooling around with this issue for over a year and never found anything satisfactory.

    Here's what I was using so far... it does the job..but there was a need to match for a pattern anyway...

    $sshMTT1->clear_accum();
$sshMTT1->expect(10,[qr/\$[\s]*/=> sub {$sshMTT1->send("grep <<<<<<*PA
+TTERN>*>>>>");}]);
@Output = $sshMTT1->expect(5);
$sshMTT1->send("\cC");
$exactOutput = $Output[3];
$exactOutput =~ tr/\cM//d;

    [download]

    The variable $exactOutput had more or less the value I was looking for and I used to pattern match on this variable... Primitive.. compared to the solution here!!!

[reply]
[d/l]
[select]

      This subroutine fails to execute the command if the executed command isn't supposed to return any value ( for example the cd command or mkdir command.

      For example if we try to execute the cd <XYZ_Directory> command using this subroutine, the directory change doesn't happen at all.

      Any help to make it fucntional for such commands is welcome

[reply]

        Any help to make it fucntional for such commands is welcome

        I would say its impossible so don't use it on such commands, or append ";pwd" so they do print output

[reply]
Re: Expect command output parser sub
by Anonymous Monk on Oct 26, 2007 at 09:54 UTC
    Great !!!!!!! You solved my problem.
[reply]
      Thank you!!!! I've been trying to figure out how to determine completion of a command, your approach is clever. If we can't get a clear indication by command, we can just insert our own! Sweet!
[reply]
        genius!! been looking for this for a few hours now...
[reply]