Actually, the string was split according to the separator. But you put the separator into parentheses, which also put the separator into the result list. Maybe it is just the way that you are printing your results that confuses you?

#!perl -w
use strict;
use Data::Dumper;

my @a1 = split /abc/, "uno abc dos";
my @a2 = split /(abc)/, "uno abc dos";

print "a1: ", Dumper \@a1;

print "a2: ", Dumper \@a2;

__END__
a1: $VAR1 = [
          'uno ',
          ' dos'
        ];
a2: $VAR1 = [
          'uno ',
          'abc',
          ' dos'
        ];
[download]

These two variants of results are what you can get using a plain split. Others have already replied with ways you can modify those results to move, for example, the second element of the array into $1, but split does not set or modify the capture variables.

First, as you see, from my example, capturing parenthesis do not work, i.e., the string is not splitted according to what I intended to be a separator: 'abc'.

Um, no

#!/usr/bin/perl --
use strict; use warnings; 
use Data::Dumper;
my @a1 = split /abc/, "uno abc dos";
my @a2 = split /(abc)/, "uno abc dos";
my @a3 = split /(?:abc)/, "uno abc dos";
print "a1 @a1\n", Dumper( \@a1 ), "\n";
print "a2 @a2\n", Dumper( \@a2 ), "\n";
print "a3 @a3\n", Dumper( \@a3 ), "\n";
__END__
a1 uno   dos
$VAR1 = [
          'uno ',
          ' dos'
        ];

a2 uno  abc  dos
$VAR1 = [
          'uno ',
          'abc',
          ' dos'
        ];

a3 uno   dos
$VAR1 = [
          'uno ',
          ' dos'
        ];
[download]

Tutorials: Debugging and Optimization: Basic debugging checklist

By the way, I'm new here, and I understood this is the site to ask for some help, if it isn't, please tell me where to go with my silly questions.

Welcome, see The Perl Monks Guide to the Monastery