fi
(echo "$list1"; echo "$list2"; echo "$list3"; echo "$list4") |
sort -u |
grep -v '^$'
awk '
BEGIN { seen_default = 0 }
/^$/ { next }
/^default$/ { seen_default = 1; next }
{ print }
END { if (seen_default) print "default" }
'
}
usage()