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, C<`hostname`>, C<`uname -n`>, and the file F. If all that fails it Cs. All nulls, returns, and newlines are removed from the result. =head1 AUTHOR David Sundstrom EFE Texas Instruments =cut sub hostname { # method 1 - we already know it return $host if defined $host; if ($^O eq 'VMS') { # method 2 - no sockets ==> return DECnet node name eval { local $SIG{__DIE__}; $host = (gethostbyname('me'))[0] }; if ($@) { return $host = $ENV{'SYS$NODE'}; } # method 3 - has someone else done the job already? It's common for the # TCP/IP stack to advertise the hostname via a logical name. (Are # there any other logicals which TCP/IP stacks use for the host name?) $host = $ENV{'ARPANET_HOST_NAME'} || $ENV{'INTERNET_HOST_NAME'} || $ENV{'MULTINET_HOST_NAME'} || $ENV{'UCX$INET_HOST'} || $ENV{'TCPWARE_DOMAINNAME'} || $ENV{'NEWS_ADDRESS'}; return $host if $host; # method 4 - does hostname happen to work? my($rslt) = `hostname`; if ($rslt !~ /IVVERB/) { ($host) = $rslt =~ /^(\S+)/; } return $host if $host; # rats! $host = ''; Carp::croak "Cannot get host name of local machine"; } elsif ($^O eq 'MSWin32') { ($host) = gethostbyname('localhost'); chomp($host = `hostname 2> NUL`) unless defined $host; return $host; } else { # Unix # method 2 - syscall is preferred since it avoids tainting problems eval { local $SIG{__DIE__}; { package main; require "syscall.ph"; } $host = "\0" x 65; ## preload scalar syscall(&main::SYS_gethostname, $host, 65) == 0; } # method 2a - syscall using systeminfo instead of gethostname # -- needed on systems like Solaris || eval { local $SIG{__DIE__}; { package main; require "sys/syscall.ph"; require "sys/systeminfo.ph"; } $host = "\0" x 65; ## preload scalar syscall(&main::SYS_systeminfo, &main::SI_HOSTNAME, $host, 65) != -1; } # method 3 - trusty old hostname command || eval { local $SIG{__DIE__}; $host = `(hostname) 2>/dev/null`; # bsdish } # method 4 - sysV uname command (may truncate) || eval { local $SIG{__DIE__}; $host = `uname -n 2>/dev/null`; ## sysVish } # method 5 - Apollo pre-SR10 || eval { local $SIG{__DIE__}; ($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;