This code started breeding within pkg.in/*/Makefile,
and it was lacking both E2K (as a generic alias,
not just "e2k or e2kv4") _and_ the ability to negate
selection, as in "everywhere but not on any e2k").

Let's fix all of that at once, and parallelize sed
execution as well; my tests with 1000-line file
containing "a b c d@!E2K e@e2k f g@!X86 h i@IA32"
lines show roughly 3x higher CPU load and lower
execution time (~0.3 sec vs ~0.9 sec on 801-PC).

And turn that code snippet into a proper filter
with inline edit capability (I've dropped the exit
trap as failing to mv signals a disaster anyway).