Expect::Simple3pm

Wrapper around the expect module

Usage

  use Expect::Simple;
  my $obj = new Expect::Simple 
        { Cmd => [ dmcoords => 'verbose=1', "infile=$infile"],
          Prompt => [ -re => 'dmcoords>:\s+' ],
          DisconnectCmd => 'q',
          Verbose => 0,
          Debug => 0,
          Timeout => 100
        };
  $obj->send( $cmd );
  print $obj->before;
  print $obj->after;
  print $obj->match_str, "\n";
  print $obj->match_idx, "\n";
  print $obj->error_expect;
  print $obj->error;
  $expect_object = $obj->expect_handle;

Overview

"Expect::Simple" is a wrapper around the "Expect" module which should suffice for simple applications. It hides most of the "Expect" machinery; the "Expect" object is available for tweaking if need be.

Generally, one starts by creating an Expect::Simple object using new. This will start up the target program, and will wait until one of the specified prompts is output by the target. At that point the caller should send() commands to the program; the results are available via the before, after, match_str, and match_idx methods. Since Expect simulates a terminal, there will be extra "\r" characters at the end of each line in the result (on UNIX at least). This is easily fixed:

    ($res = $obj->before) =~ tr/\r//d;
    @lines = split( "\n", $res );

This is not done automatically.

Exceptions will be thrown on error (match with "/Expect::Simple/"). Errors from Expect are available via the error_expect method. More human readable errors are available via the error method.

The connection is automatically broken (by sending the specified disconnect command to the target) when the Expect::Simple object is destroyed.

Methods

new

    $obj = Expect::Simple->new( \%attr );

This creates a new object, starting up the program with which to communicate (using the Expect spawn method) and waiting for a prompt. The passed hash reference must contain at least the Prompt, DisconnectCmd, and Cmd elements. The available attributes are:

Cmd: Cmd => $command, Cmd => [ $command, $arg1, $arg2, ... ],

The command to which to connect. The passed command may either be a scalar or an array.

Prompt

This specifies one or more prompts to scan for. For a single prompt, the value may be a scalar; for more, or for matching of regular expressions, it should be an array reference. For example,

  Prompt => 'prompt1> ',
  Prompt => [ 'prompt1> ', 'prompt2> ', -re => 'prompt\d+>\s+' ]

All prompts are taken literally, unless immediately preceded by a "-re" flag, in which case they are regular expressions.

DisconnectCmd: This is the command to be sent to the target program which will cause it to exit.

RawPty: If set, then underlying Expect object's pty mode is set to raw mode (see Expect::raw_pty()).

Timeout: The time in seconds to wait until giving up on the target program responding. This is used during program startup and when any commands are sent to the program. It defaults to 1000 seconds.

Debug: The value is passed to Expect via its debug method.

Verbose: This results in various messages printed to the STDERR stream. If greater than 3, it turns on Expect's logging to STDOUT (via the log_stdout Expect method.

send: $obj->send( $cmd ); $obj->send( @cmds );

Send one or more commands to the target. After each command is sent, it waits for a prompt from the target. Only the output resulting from the last command is available via the after, before, etc. methods.

match_idx: This returns a unary based index indicating which prompt (in the list of prompts specified via the "Prompt" attribute to the new method) was received after the last command was sent. It will be undef if none was returned.

match_str: This returns the prompt which was matched after the last command was sent.

before: This returns the string received before the prompt. If no prompt was seen, it returns all output accumulated. This is usually what the caller wants to parse. Note that the first line will (usually) be the command that was sent to the target, because of echoing. Check this out to be sure!

after: This returns the 'after' string. Please read the Expect docs for more enlightenment.

error: This returns a cleaned up, more humanly readable version of the errors from Expect. It'll be undef if there was no error.

error_expect: This returns the original Expect error.

expect_handle: This returns the Expect object, in case further tweaking is necessary.

Releases

9 releases since Debian 5.0 (Lenny); the text changed 3 times.

Bugs

If the command to be run does not exist (or not in the current execution path), it's quite possible that the new method will not throw an exception. It's up to the caller to make sure that the command will run! There's no known workaround for this.

License

This software is released under the GNU General Public License. You may find a copy at

   http://www.fsf.org/copyleft/gpl.html

Author

Diab Jerius ([email protected])

From libexpect-simple-perl 0.04-3 in Debian 13 (Trixie). Parsed by carta from the page's man source.