df | sed -n 's/.*\([0-9]\)%.*/\1/p'
i've been trying that. it will get you the last digit, but not the one in tens place. i dont know why a
df | sed -n 's/.*\([0-9]+\)%.*/\1/p'
of course, you can add another [0-9] but that will only return if you have a number with 2 digits.
slackie: that one will fail if you dont have /dev in your line (for instance, for swap)