Finding Your Own Name and Address
Problem
You want to find your (fully qualified) hostname.
Solution
First, get your (possibly qualified) hostname. Either try the standard Sys::Hostname module:
use Sys::Hostname; $hostname = hostname();
or POSIX’s uname
function:
use POSIX qw(uname); ($kernel, $hostname, $release, $version, $hardware) = uname(); $hostname = (uname)[1]; # or just one
Then turn it into an IP address and convert to its canonical name:
use Socket; # for AF_INET $address = gethostbyname($hostname) or die "Couldn't resolve $hostname : $!"; $hostname = gethostbyaddr($address, AF_INET) or die "Couldn't re-resolve $hostname : $!";
Discussion
Sys::Hostname tries to be portable by using knowledge about your system to decide how best to find the hostname. It tries many different ways of getting the hostname, but several involve running other programs. This can lead to tainted data (see Section 19.1).
POSIX::uname
, on the other hand, only works on
POSIX systems and isn’t guaranteed to provide anything useful
in the nodename
field that we are examining. That
said, the value is useful on many machines and
doesn’t suffer from the tainted data problem that Sys::Hostname
does.
Once you have the name, though, you must consider that it might be
missing a domain name. For instance, Sys::Hostname may return you
guanaco
instead of
guanaco.camelids.org
. To fix this, convert the
name back into an IP address with gethostbyname
and then back into a name again with
gethostbyaddr
. By involving the ...
Get Perl Cookbook now with the O’Reilly learning platform.
O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.