#this is a file with comments
#another line
# how do I grep for uncoimmented lines?
try grep -v '^#' <file>
# that works
but grep -nv '^#' <file> is even better
# another comment

#preceeding line was whitespace
but this is real.

And now we can exclude whitespace or empty lines:
grep -nvE '^#|^ |^$' grepcomments
#rox