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up vote -2 down vote favorite

so what I want to do is remove everything after and including the first "/" to appear after a "." so: http://linux.pacific.net.au/primary.xml.gz would become: http://linux.pacific.net.au

How do I do this using regex? The system I'm running on can't use URI tool.

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2  
I assume you have tried something and couldn't do it. Show us your work first. – Hameed Aug 9 '12 at 1:48
Just because you can't use a Perl module doesn't mean that you can't look inside it to see what it does and how it does it. – brian d foy Aug 9 '12 at 18:31

3 Answers

up vote 5 down vote accepted

I suggest you use URI::Split which will separate a standard URL into its constuent parts for you and rejoin them. You want the first two parts - the scheme and the host.

use strict;
use warnings;

use URI::Split qw/ uri_split uri_join /;

my $scheme_host = do {
  my (@parts) = uri_split 'http://linux.pacific.net.au/primary.xml.gz';
  uri_join @parts[0,1];
};

print $scheme_host;

output

http://linux.pacific.net.au

Update

If your comment The system I'm running on can't use URI tool means you can't install modules, then here is a regular expression solution.

You say you want to remove everything after and including the first "/" to appear after a ".", so /^.*?\./ finds the first dot, and m|[^/]+| finds everything after it up tot he next slash.

The output is identical to that of the preceding code

use strict;
use warnings;

my $url = 'http://linux.pacific.net.au/primary.xml.gz';

my ($scheme_host) = $url =~ m|^( .*?\. [^/]+ )|x;

print $scheme_host;
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I have a feeling it is a assignment question and s/he needs to build the regex... – Hameed Aug 9 '12 at 2:57
@Hameed: Hmm maybe. I've also just realised that The system I'm running on can't use URI tool probably means the URI module – Borodin Aug 9 '12 at 3:11
up vote 4 down vote

The system I'm running on can't use URI tool.

I really recommend doing whatever you can to fix that problem first. If you're not able to use CPAN modules then you'll be missing out on a lot of the power of Perl and your Perl programming life will be far more frustrating than it needs to be.

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I'm actually surprised to discover that URI is not in the core these days. – friedo Aug 9 '12 at 14:07
up vote 3 down vote 
$url = 'http://linux.pacific.net.au/primary.xml.gz';
($domain) = $url =~ m!(https?://[^:/]+)!;
print $domain;

output:

http://linux.pacific.net.au

and this is the official regular expression can be used to decode a URI:

  my($scheme, $authority, $path, $query, $fragment) =
  $uri =~ m|(?:([^:/?#]+):)?(?://([^/?#]*))?([^?#]*)(?:\?([^#]*))?(?:#(.*))?|;
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