I would suggest using the same @file option that GCC and other tools support but that's out of question since the syntax is now used by sets. But some kind of parameter would definitely be helpful. I'm using xargs to fetch the tree for tinderboxing, but the result is sub-optimal because most of the time the list is too big for a single emerge fetch run, and it's split in two calls.
What's wrong with this usage? emerge -p $(some command | cut | sed | whatever)
ARG_MAX is the problem. When you got a list of packages that is around 150K big, you hit ARG_MAX pretty hard. And xargs need to split that in two calls because it can only pass around 6200 atoms in one go.
(In reply to Diego Elio Pettenò from comment #0) > I would suggest using the same @file option that GCC and other tools support > but that's out of question since the syntax is now used by sets. But some > kind of parameter would definitely be helpful. why not just make a temporary set then? for this specific scenario (i.e. for fetching), there seem to be no features of emerge that would make one go better than multiple.