Here's some code that generates a hash similar to Jeffa's, but it's not a one liner. Meant for use in another program...
#!/usr/bin/perl
use warnings;
use strict;
# Hash that we'll store all the values (the name) in; keys are ports i
+n
# the form of ###/proto, i.e. 22/tcp
my %port2name;
open my $fh, '<', '/etc/services' or die "Failed open! $!";
while (<$fh>) {
next if /^#/ || /^$/;
chomp;
s/\s*#.*$//;
my ($name, $port) = split /\s+/, $_;
$port2name{$port} = $name;
}
close $fh;
# ... do whatever with the hash now
# For example, grab arguments from command line and
# print out name for each
for (@ARGV) {
print exists $port2name{$_}
? "$_: $port2name{$_}"
: 'Unknown port/proto combination.', "\n";
}