On 4/1/06, Sick Twist <thesicktwist@hotmail.com> wrote:
p> I am trying to write a script that parses an unknown IP address from a page
> of HTML, compares the IP address to a file and overwrites the file if the
> saved IP address is different. My question is, what language should I
> investigate to accomplish this? Is this able to be done with a bash script
> and command line utilities or is there another language like perl or python
> that would be better suited for this task? C has always been my game so I'm
> less familiar with the strengths and capabilities of some of the other tools
> out there. Thanks in advance!
I'd use perl.
The following is completely untested, but it should work.
And no, this isn't my april fools. :)
It requires LWP::Simple, part of the www perl library, which on debian
(and probably ubuntu) is libwww-perl.
#!/usr/bin/perl
use strict;
use warnings;
use LWP::Simple 'get';
use IO::File;
my $url = 'http://whatismyip.com';
my $file = 'myipfile';
update_ipfile($file, fetch_old_ip($file), fetch_ip($url));
sub fetch_ip {
my ($url) = @_;
my $html = get($url);
if ($html =~ /(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})/s) {
my $ip = $1;
print "Found IP: $ip\n";
return $ip;
} else {
die "Cannot find ip address on $url\n";
}
}
sub fetch_old_ip {
my ($file) = @_;
# If $file exists, we open it and read the first line.
if (-e $file) {
my $fh = new IO::File($file, 'r') or die "Cannot open $file: $!";
my $line = $fh->getline;
chomp $line;
$fh->close;
return $line;
} else {
# Return something that cannot be an IP.
return "(nada)";
}
}
sub update_ipfile {
my ($file, $old_ip, $ip) = @_;
if ($old_ip ne $ip) {
print "Changing IP to $ip (was $old_ip)\n";
my $fh = new IO::File($file, 'w') or die "Cannot open $file for writing: $!";
$fh->print($ip);
$fh->close;
} else {
print "Old IP and new IP are the same ($ip).\n";
}
}
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