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Expect - choreographing multiple pings and analysing result
Interprocess Communication example from a Well House Consultants training course
More on Interprocess Communication [link]

This example is described in the following article(s):
   • Expect in Perl - a short explanation and a practical example - [link]

Source code: check Module: P223
#!/usr/bin/env perl

use Expect;

# Subroutine to handle each line returned

sub linebyline {
        # Grab the information from the expect_out buffer
        $line = $exp->before();
        if ($line =~ /\((\d+\.\d+\.\d+\.\d+)\)/) {
                print "At $1\n";
        if ($line =~ /time=([\d\.]+)\s*(\w+)/) {
                print "Round trip - $1 $2\n";
        if ($line =~ /(\d+) packets transmitted, (\d+) packets received/) {
                print "$2 of $1 received\n";
                $result{$host} = ("Failed","1/3","2/3","AOK")[$2];

@hosts = ("www.wellhousemanor.co.uk","www.wellho.net","www.sheepbingo.co.uk",

# Loop through each host of interets

foreach $host(@hosts) {

print "\nChecking $host ...\n";
$result{$host} = "no result recorded";

# start a spawn process
$exp = Expect->spawn("ping -c3 $host") or die ("Cannot Spawn");
# turn off echo of results on to screen

$trigger = 1;

# read results backline by line, with timeout and end of file trapped
while ($trigger) {
        $exp->expect( 5,
                [qr"\r\n" => \&linebyline ] ,
                [timeout => sub {$trigger = 0; print "TIMED OUT\n";
                        $result{$host} = "Timed Out"; }] ,
                [eof => sub {$trigger = 0}] );


# Print final analysis table

print "\nCompleted ... \n";
foreach $host(sort {$result{$a} cmp $result{$b}} keys %result) {
        printf ("%-10s %s\n",$result{$host},$host);


Sample output:

wizard:csr2 graham$ ./check

Checking www.wellhousemanor.co.uk ...
Round trip - 100.171 ms
Round trip - 68.998 ms
Round trip - 84.314 ms
3 of 3 received

Checking www.wellho.net ...
Round trip - 29.984 ms
Round trip - 50.758 ms
Round trip - 130.806 ms
3 of 3 received

Checking www.sheepbingo.co.uk ...
Round trip - 43.693 ms
Round trip - 44.986 ms
Round trip - 48.093 ms
3 of 3 received

Checking control.wellho.net ...

Checking office.wellho.net ...
Round trip - 110.232 ms
Round trip - 111.055 ms
Round trip - 130.407 ms
3 of 3 received

Checking manor.wellho.net ...
Round trip - 173.806 ms
1 of 3 received

Checking wellho.net ...
Round trip - 475.397 ms
Round trip - 398.913 ms
Round trip - 316.539 ms
3 of 3 received

Completed ...
1/3 manor.wellho.net
AOK wellho.net
AOK office.wellho.net
AOK www.wellhousemanor.co.uk
AOK www.wellho.net
AOK www.sheepbingo.co.uk
Timed Out control.wellho.net
wizard:csr2 graham$

Learn about this subject
This module and example are covered on our public Perl Extra course. If you have a group of three or more trainees who need to learn the subject, we can also arrange a private or on site course for you.

Books covering this topic
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Other Examples
This example comes from our "Interprocess Communication" training module. You'll find a description of the topic and some other closely related examples on the "Interprocess Communication" module index page.

Full description of the source code
You can learn more about this example on the training courses listed on this page, on which you'll be given a full set of training notes.

Many other training modules are available for download (for limited use) from our download centre under an Open Training Notes License.

Other resources
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This web site is written and maintained by Well House Consultants.

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This is a sample program, class demonstration or answer from a training course. It's main purpose is to provide an after-course service to customers who have attended our public private or on site courses, but the examples are made generally available under conditions described below.

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