gethostbyname: What does $aliases look like?

[Skeeve]

I wrote a small script where I use

($name, $aliases, $addrtype, 
          $length, @addrs) = gethostbyname $host;

and since I don't have any host having more than 2 names (i.e. 1 alias) I don't know what $aliases would look like, had the machine 3 or more names.

Are the names in a string? Space seperated? Komma seperated?

Or wil $aliases be a reference to an array?

Can someone please enlighten me?

[tomfahle]

Just add some aliases where it doesn't hurt and it's easy to figure out. (I use a tiny virtual machine for this purpose.)

#!/usr/bin/perl
use strict;
use warnings;

use Dumpvalue;  # Core Module, dumps like the debugger

my $dumper = new Dumpvalue;

my $host = shift;

my ($name,$aliases,$addrtype,$length,@addrs) = gethostbyname($host) or
+ die "Can't resolve $host $!\n";


print "$aliases\n";
$dumper->dumpValue(\$aliases);

My /etc/hosts file

127.0.0.1    localhost    tf-laptop    my-laptop

Running the above code with the argument localhost yields:

$ perl gethostbyname.pl localhost
tf-laptop my-laptop
-> 'tf-laptop my-laptop'

$aliases is a string holding the aliases seperated by whitespace.

Hth
Thomas

[ikegami]

An array of strings, I would suppose, like the system call.

Then again, Perl doesn't return an array when there's only one alias. Maybe it returns one at most?

$ perl -MData::Dumper -e'print Dumper $_ for (gethostbyname $ARGV[0])[
+0,1]' www.google.com
$VAR1 = 'www.l.google.com';
$VAR1 = 'www.google.com';

Update: They are space-joined. From pp_sys.c:

PUSHs(space_join_names_mortal(hent->h_aliases));

[Skeeve]

Thanks, ikegami