First, sorry to anybody who has emailed me or attempted to contact me on
IRC recently.  I've been out of town for a few days.

This morning I started wondering where USE flags are actually used in
the ebuilds, so I quickly generated a report.  Here is the generator and
the output, in case anybody else is interested.  Yes, the generator is
a hack, I just wrote it out quickly on the commandline.

$ cd /usr/portage
$ find . -type d | 
    while read d; do 
	/bin/ls -t1 $d/*.ebuild 2>/dev/null | head -1
    done | 
    xargs perl -ne '
	s/#.*//; 
	s/^\s*//; 
	/DESCRIPTION/ && next; 
	($f = $ARGV) =~ s|.*/||; 
	/\buse\s+(\w+)/ || next; 
	printf "%-20s %-30s %s", $1, $f, $_' | 
    sort > report.txt

Note there are some false ones in the mix that I didn't bother to weed
out.  That's why the line from the ebuild is included in the report, so
that those are apparent.

Of additional interest are those USE flags, set in /etc/make.conf, that
are never referenced in any ebuilds.  Those are listed below.  (Btw,
I realize this is just about the least efficient way of producing this
report.  That's not my goal here.)

$ . /etc/make.conf
$ for u in $USE; do grep -q "^$u" report.txt || echo $u; done
lm_sensors
libg++

Aron