Net::servent - by-name interface to Perl's built-in getserv*() functions
use Net::servent;
$s = getservbyname(shift || 'ftp') || die "no service";
printf "port for %s is %s, aliases are %s\n",
$s->name, $s->port, "@{$s->aliases}";
use Net::servent qw(:FIELDS);
getservbyname(shift || 'ftp') || die "no service";
print "port for $s_name is $s_port, aliases are @s_aliases\n";
This module's default exports override the core getservent(),
getservbyname(), and
getnetbyport() functions, replacing them with versions that return
``Net::servent'' objects. They take default second arguments of ``tcp''. This object has methods that return the similarly
named structure field name from the C's servent structure from netdb.h;
namely name, aliases, port, and proto. The aliases
method returns an array reference, the rest scalars.
You may also import all the structure fields directly into your namespace
as regular variables using the :FIELDS import tag. (Note that this still
overrides your core functions.) Access these fields as variables named
with a preceding n_. Thus, $serv_obj->name() corresponds to
$s_name if you import the fields. Array references are available as
regular array variables, so for example @{ $serv_obj->aliases()
} would be simply @s_aliases.
The getserv() function is a simple front-end that forwards a numeric
argument to getservbyport(), and the rest to getservbyname().
To access this functionality without the core overrides,
pass the use an empty import list, and then access
function functions with their full qualified names.
On the other hand, the built-ins are still available
via the CORE:: pseudo-package.
use Net::servent qw(:FIELDS);
while (@ARGV) {
my ($service, $proto) = ((split m!/!, shift), 'tcp');
my $valet = getserv($service, $proto);
unless ($valet) {
warn "$0: No service: $service/$proto\n"
next;
}
printf "service $service/$proto is port %d\n", $valet->port;
print "alias are @s_aliases\n" if @s_aliases;
}
While this class is currently implemented using the Class::Struct
module to build a struct-like class, you shouldn't rely upon this.
Tom Christiansen
