if ($line =~ /blablabla :(.+?): bleblable/){
$my_var = fixn($1);
do_whatever_I_want_with($my_var);
} 
##</code><code>##

sub fixn($){
        my $str = "@_";
        $str =~ s/[^a-zA-Z0-9^_\-\\`\.\[\]\{\}~]//g;
        chomp $str;
        return $str;
}