@world versus world...what's the difference?

[Spankin Partier]

Ok, noob question here... what's the difference between @world and just plain world or @system and system?

I've recently started noticing the @ symbol being added to some emerge commands, when I tried reading the man pages or searching with Google (which conveniently ignores the @ symbol ) I come up empty. I this just a new addition to portage's grammar?

[few]

@ indicates a package set. In portage-2.1 there are only @world and @system. In portage-2.2 there are more (emerge --list-sets). In both cases world and system are aliases for the correspnding sets, which means there is no difference. Other sets don't have such aliases.

[Spankin Partier]

So best practices now dictates that one should always use the @ symbol whenever calling a package set so one doesn't forget it when calling a non aliased set.

I'll have to keep an eye out for the new package sets when my systems start to upgrade 2.2. Thanks.