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package Sys::Hostname;
use Carp;
require Exporter;
@ISA = qw(Exporter);
@EXPORT = qw(hostname);
=head1 NAME
Sys::Hostname - Try every conceivable way to get hostname
=head1 SYNOPSIS
use Sys::Hostname;
$host = hostname;
=head1 DESCRIPTION
Attempts several methods of getting the system hostname and
then caches the result. It tries C<syscall(SYS_gethostname)>,
C<`hostname`>, C<`uname -n`>, and the file F</com/host>.
If all that fails it C<croak>s.
All nulls, returns, and newlines are removed from the result.
=head1 AUTHOR
David Sundstrom <sunds@asictest.sc.ti.com>
Texas Instruments
=cut
sub hostname {
# method 1 - we already know it
return $host if defined $host;
# method 2 - syscall is preferred since it avoids tainting problems
eval {
{
package main;
require "syscall.ph";
}
$host = "\0" x 65; ## preload scalar
syscall(&main::SYS_gethostname, $host, 65) == 0;
}
# method 3 - trusty old hostname command
|| eval {
$host = `(hostname) 2>/dev/null`; # bsdish
}
# method 4 - sysV uname command (may truncate)
|| eval {
$host = `uname -n 2>/dev/null`; ## sysVish
}
# method 5 - Apollo pre-SR10
|| eval {
($host,$a,$b,$c,$d)=split(/[:\. ]/,`/com/host`,6);
}
# bummer
|| Carp::croak "Cannot get host name of local machine";
# remove garbage
$host =~ tr/\0\r\n//d;
$host;
}
1;
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