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Use LWP UserAgent to check and see if a remote site has changed
Standard Web Modules example from a Well House Consultants training course
More on Standard Web Modules [link]
Source code: cc2 Module: P408
use LWP::UserAgent;
# Get remote site name $site = $ARGV[0] || "www.wellho.net"; $limit = 100; @omit = ("cgi"); # Keep a local mirror for next time comparison mkdir $site if (! -e $site) ; # Grab robots.txt; alert user if it has changed and (manual) check is needed $agent = LWP::UserAgent->new; $agent->agent("Well House Consultants"); @alt = ("Not Available","Changed","Unchanged","Freshly Collected"); getpage("http://$site/robots.txt"); die "robots.txt was $alt[$altered]\n" if ($altered%2); # Start at index.html ... @pagequeue = ("http://$site/index.html"); while ($file = shift @pagequeue) { next if ($already{$file}); # Skip pages already checked last if (++$npages > $limit); # limit pages to handle sleep 5 unless ($npages%10); # Pause to prevent denial of service attack $already{$file} = $stat = getpage($file); if ($altered == 1 or $altered == 3) { print "$file: $stat, page was $alt[$altered]\n"; $alert++; } # Convert links found so that they can be compared foreach (@links) { $fully = URI ->new_abs($_,$file) ->canonical; $fully =~ s/#.*//; $hopper = 1; foreach $leave (@omit) { $hopper = 0 if ($fully =~ /$leave/) } if ($fully =~ m!^http://$site/!i and $hopper) { push @pagequeue,$fully; } } } $alert and print "alter count is $alert\n"; ################################# sub getpage { $req = HTTP::Request->new(GET => ($pagewant=$_[0])); $res = $agent->request($req); $altered = 0; @links = (); if (($status = $res->code()) == 200) { ($mirrorname = $pagewant) =~ tr!/:!%=!; $page = $res -> content(); $altered = 3; if (-e "$site/$mirrorname") { open (FH,"$site/$mirrorname"); read (FH, $oldpage, -s "$site/$mirrorname"); $altered = ($page eq $oldpage) + 1; } open (FH,">$site/$mirrorname"); print FH $page; @links = ($page =~ m/href\s*=\s*"?([^">\s]+)/ig); } return ($status); } Learn about this subject
This module and example are covered on our public Using Perl on the Web course. If you have a group of
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private or on site course for you.
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Other Examples
This example comes from our "Standard Web Modules" training module. You'll find a description of the topic and some
other closely related examples on the "Standard Web Modules" module index page.
Full description of the source code
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