gethostbyname: What does $aliases look like?

Skeeve has asked for the wisdom of the Perl Monks concerning the following question:

I wrote a small script where I use

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

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?

s$$([},&%#}/&/]+}%&{})*;#$&&s&&$^X.($'^"%]=\&(|?*{%
+.+=%;.#_}\&"^"-+%*).}%:##%}={~=~:.")&e&&s""`$''`"e

Comment on gethostbyname: What does $aliases look like? Select or Download Code

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Re: gethostbyname: What does $aliases look like? by tomfahle (Priest) on Sep 14, 2009 at 07:32 UTC
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"; $dumper->dumpValue(\$aliases);` [download] My /etc/hosts file `127.0.0.1 localhost tf-laptop my-laptop` [download] Running the above code with the argument localhost yields: `$ perl gethostbyname.pl localhost tf-laptop my-laptop -> 'tf-laptop my-laptop'` [download] $aliases is a string holding the aliases seperated by whitespace. Hth Thomas	[reply] [d/l] [select]
Re: gethostbyname: What does $aliases look like? by ikegami (Patriarch) on Sep 14, 2009 at 06:58 UTC
An array of strings, I would suppose, like the system call. Then again, Perl doesn't return an array when there's only one alias. Maybe it returns one at most? `$ perl -MData::Dumper -e'print Dumper $_ for (gethostbyname $ARGV[0])[ +0,1]' www.google.com $VAR1 = 'www.l.google.com'; $VAR1 = 'www.google.com';` [download] Update: They are space-joined. From `pp_sys.c`: `PUSHs(space_join_names_mortal(hent->h_aliases));` [download]	[reply] [d/l] [select]
Re^2: gethostbyname: What does $aliases look like? by Skeeve (Parson) on Sep 14, 2009 at 07:12 UTC
Thanks, ikegami `s$$([},&%#}/&/]+}%&{});#$&&s&&$^X.($'^"%]=\&(\|?{%` `+`.+=%;.#_}\&"^"-+%*).}%:##%}={~=~:.")&e&&s""`$''`"e	[reply] [d/l] [select]


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