[ILUG] Re: Need Help with Perl Script

[Peter Heslin]

On Tue, May 02, 2000 at 03:45:57PM +0100, Dave O Connor wrote:
> That'd ouput the return value from that nasty shell command, which you don't
> really want. A slightly more efficient (resourcewise, anyway) would be
> something like:
> 
> sub num_users
> {
> 	open(USERS,"/usr/bin/users|");
> 
> 	my $users = <USERS>;
> 
> 	close USERS;
> 
> 	my @userlist = split(/\s+/,$users);
> 
> 	my @uniqlist;
> 
> 	foreach (@userlist)
> 	{
> 		if (!grep($_, at uniqlist))
> 		{
> 			push(@uniqlist,$_);
> 		}
> 	}
> 
> 	return scalar @uniqlist;
> }

Same idea:

perl -e 'print "There are ", scalar keys %{{map {$_ => 1} split " ", `users`}}, " users logged in.\n"'

Hashes are useful for finding unique elements in a list.

Peter