Beginning Web Development With Perl : From Novice to ... - Nabo

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130CHAPTER 6 ■ NET:: TOOLSFor example, if you want to change the protocol from its default TCP, do so when creatingthe ping object. This example sets the protocol to ICMP:$pingobj = Net::Ping->new('icmp');Separate multiple arguments with commas when invoking new. For example, to set timeoutto 10 seconds, explicitly set the protocol first, and then set the timeout:$pingobj = Net::Ping->new('icmp', 10);Sending an ICMP Echo RequestUsing Net::Ping to send an ICMP echo request requires root privileges or that the Perl programbe setuid root. I won’t promote the use of setuid. Therefore, if you want to run an ICMP-basedcheck with Net::Ping, the program will need to be run as root. I dislike this option as well, butI’m choosing the lesser of two evils.Listing 6-15 (Pingex1.pl) sends a simple ICMP echo request to a host on the Internet andfrom there, reports on the response.Listing 6-15. A Simple Ping#!/usr/bin/perl -wuse Net::Ping;use strict;my $pingobj = Net::Ping->new('icmp');my $host = "www.google.com";my ($status,$time,$ip) = $pingobj->ping($host);if ($status) {print "Host $host ($ip) responded in $time seconds\n";} else {print "Host $host ($ip) unreachable\n";}■Note Don’t forget that you need root privilege to run the program in Listing 6-15. If you see an error similarto icmp ping requires root privilege, that means you don’t have root privilege!This example first invokes the new() method, creating the ping object, called $pingobj. Thecall to new() also changes the protocol to ICMP. Next, the host is set, which is www.google.com inthis example. The ping() method is called against the $pingobj with the argument of the host tobe pinged.
CHAPTER 6 ■ NET:: TOOLS 131When called in scalar context, the ping() method returns 1 for success or undef for a failure(an unsuccessful ping). When called in a list context, the ping() method returns the success flag(1 for success), the time that the operation took, and the IP address used.When run, the program produces output like this:Host www.google.com (64.233.167.104) responded in 0 secondsThe time returned by ping() is sent in integer format by default. This means that, manytimes, the time will be integer 0, since the ping operation took less than a second. To obtainmore accurate times, use the Time::HiRes module, as described in the next section.The final section of the example evaluates the $status variable. If the $status variable is1, the ping was successful and the results are printed. If the $status variable is 0, the ping wasunsuccessful and the corresponding result is also printed.Getting More Accurate TimesAs previously stated, the time returned by ping() is returned in integer seconds. This is fine if allyou’re looking for is success or failure of the ping operation as a whole. However, if you want toobtain more accurate times, you need to use the Time::HiRes module, available from CPAN. Thecode in Listing 6-16 (Pingex2.pl) is essentially the same as Listing 6-15, with two exceptions: theTime::HiRes module is brought into the namespace, and it includes a call to the hires() methodon the ping object.Listing 6-16. A Ping Using Time::HiRes for More Accurate Times#!/usr/bin/perl -wuse Net::Ping;use Time::HiRes;use strict;my $pingobj = Net::Ping->new('icmp');my $host = "www.google.com";$pingobj->hires();my ($status,$time,$ip) = $pingobj->ping($host);if ($status) {print "Host $host ($ip) responded in $time seconds\n";} else {print "Host $host ($ip) unreachable\n";}When run, the program produces output similar to that shown here:Host www.google.com (64.233.167.104) responded in 0.0691518783569336 seconds
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Beginning Web Development with Perl
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PART 5 ■ ■ ■ Creating Web Tem
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■CONTENTSvii■CHAPTER 4 System I
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■CONTENTSixCreating a SOAP Listen
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■CONTENTSxiTemplate Toolkit Synta
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About the Author■STEVE SUEHRING i
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AcknowledgmentsThanks to James Lee
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xx■INTRODUCTIONThis book will use
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CHAPTER 1■ ■ ■The CGI ModuleT
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CHAPTER 1 ■ THE CGI MODULE 5for t
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CHAPTER 1 ■ THE CGI MODULE 9exit;
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CHAPTER 1 ■ THE CGI MODULE 33Also
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CHAPTER 2■ ■ ■Popular CGI Mod
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CHAPTER 2 ■ POPULAR CGI MODULES 3
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50CHAPTER 3 ■ DATABASES AND PERLT
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52CHAPTER 3 ■ DATABASES AND PERLm
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54CHAPTER 3 ■ DATABASES AND PERLl
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56CHAPTER 3 ■ DATABASES AND PERLc
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58CHAPTER 3 ■ DATABASES AND PERLR
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62CHAPTER 3 ■ DATABASES AND PERLw
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64CHAPTER 3 ■ DATABASES AND PERLA
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74CHAPTER 4 ■ SYSTEM INTERACTION
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76CHAPTER 4 ■ SYSTEM INTERACTIONt
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Page 104 and 105: CHAPTER 5■ ■ ■LWP ModulesLWP
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Page 126 and 127: 112CHAPTER 6 ■ NET:: TOOLSmy $pop
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Page 148 and 149: PART 3■ ■ ■XML and RSS
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Page 168 and 169: 156CHAPTER 8 ■ PERL AND RSShttp:/
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Page 192 and 193: PART 4■ ■ ■PerformanceEnhance
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184CHAPTER 10 ■ APACHE AND MOD_PE
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202CHAPTER 11 ■ DEVELOPMENT WITH
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CHAPTER 12■ ■ ■The Template T
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CHAPTER 12 ■ THE TEMPLATE TOOLKIT
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CHAPTER 13■ ■ ■Perl Web Sites
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CHAPTER 13 ■ PERL WEB SITES WITH
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284APPENDIX ■ PERL BASICSKeywords
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286APPENDIX ■ PERL BASICS$ perl n
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288APPENDIX ■ PERL BASICSAnd line
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290APPENDIX ■ PERL BASICSCan you
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292APPENDIX ■ PERL BASICSBy defau
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294APPENDIX ■ PERL BASICS#!/usr/b
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296APPENDIX ■ PERL BASICSThe last
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298APPENDIX ■ PERL BASICSThe NOT
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300APPENDIX ■ PERL BASICSprint "S
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302APPENDIX ■ PERL BASICSthe syst
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304APPENDIX ■ PERL BASICS$ perl s
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306APPENDIX ■ PERL BASICSThis cod
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308APPENDIX ■ PERL BASICS$a = 6 *
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310APPENDIX ■ PERL BASICS$a = "A9
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312APPENDIX ■ PERL BASICS#!/usr/b
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314APPENDIX ■ PERL BASICSmy $name
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316APPENDIX ■ PERL BASICSis short
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318APPENDIX ■ PERL BASICSLet’s
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320APPENDIX ■ PERL BASICSOther Te
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322APPENDIX ■ PERL BASICS}}}actio
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324APPENDIX ■ PERL BASICSNotice t
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326APPENDIX ■ PERL BASICSLooping
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328APPENDIX ■ PERL BASICSuse stri
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330APPENDIX ■ PERL BASICSuntil ($
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332APPENDIX ■ PERL BASICSuse stri
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334APPENDIX ■ PERL BASICSdoneAll
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336APPENDIX ■ PERL BASICS$ perl r
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338APPENDIX ■ PERL BASICSSummaryT
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340■INDEXmethods for retrieving r
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342■INDEXdo() method for, 62dumpi
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344■INDEXhello option for Net::SM
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346■INDEXNet::DNS module, 125-128
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348■INDEXrecord with Net::DNS mod
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350■INDEXstoring mail server in e
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352■INDEXlogging based on, 229pri
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