here is a list of the commands and what output they produce (btw I use Leopard OS X):

uptime | cut -d" " -f4-8 | sed 's/,//g'

-> up 9 mins 2 users



uptime | sed 's/, *[0-9]* users.*$//'

-> 0:18 up 10 mins



uptime | sed 's/.*up \(.*\),.user.*/\1/'
-> 0:19 up 10 mins, 2 users, load averages: 0,61 0,54 0,31



I want it look like that: x days y h z min
I do not want to see the current time, the word up, commas, colons nor the load averages. Furthermore if the machine has only be running for a couple of minutes it should look like that: z min
-> so the output should print nothing else except the minutes (for hours the same: it should not display days yet)
I have been playing around with uptime | awk etc. but this command did not produce the required output since it changes depending on how long the machine has been running for.
Is there a command that solves my problem or is it impossible to produce the required output due to the changing uptime of the computer?