A Beginner's Guide to Perl Expect Bindings - A Simple Walkthrough

21 February 2012

Basic Perl “Hello World” Script (hello.pl) #

Let’s start with the basics. Here is a straightforward “Hello World” script written in Perl. Create a new file and name it hello.pl.

#!/usr/bin/perl
use strict;
use warnings;
use diagnostics;

print "-----------\n",
      "Hello World\n",
      "-----------\n";

In this script, we’re using Perl’s built-in modules for error handling (use strict; use warnings; use diagnostics;) to make sure the code is robust.

Introducing Expect Bindings with Perl (test.pl) #

Now, let’s dive into the main topic: how to use Expect bindings in a Perl script. Create another file, test.pl, and add the following code:

#!/usr/bin/perl
use strict;
use warnings;
use diagnostics;
use Expect;

my $timeout = 5;  # set timeout to 5 seconds
for my $i (1..20) {  # loop 20 times
    my $exp = Expect->spawn("./hello.pl")  # execute the hello.pl script
        or die "Couldn't spawn the process: $!\n";
    $exp->expect($timeout);  # wait for the process to complete
}

In this example, the Expect->spawn("./hello.pl") line runs the hello.pl script, and we use the expect method to wait for it to finish. We’ve also set a timeout for the script, ensuring it doesn’t hang indefinitely.