open(ALIASES3, "+<$aliases_file") or &error("Kann die Datei $aliases_file nicht lesen!");
    while (<ALIASES3>){
        push(@aliases4, $_);
    }
    close (ALIASES3);
    open(ALIASES4, ">$aliases_file") or &error("Kann die Datei $aliases_file nicht lesen!");
    while (<@aliases4>){    
        print ALIASES4 $_."\n";
    } 
    close (ALIASES4);

admin:
admin@localhost
user:
user@localhost
user2:
user2@localhost

admin: admin@localhost
user: user@localhost
user2: user2@localhost

open(my $read_aliases, "<$aliases_file") or &error("Kann die Datei $aliases_file nicht lesen!");
my @aliases = <$read_aliases>
close ($read_aliases);

open(my $write_aliases, ">$aliases_file") or &error("Kann die Datei $aliases_file nicht oeffnen!");
print $write_aliases $_ for(@aliases);
close $write_aliases;