@perderabo

the command you used does not work either because you don't use the command uptime you use echo "0:19 up 10 mins, 2 users, load averages: 0,61 0,54 0,31" | sed 's/.*up \(.*\),.user.*/\1/'
and that command will always produce 10 mins as the uptime
and if I change it to
uptime | sed 's/.*up \(.*\),.*user.*/\1/'
the output is the following
-> 6:58

which is my current uptime! (thx so far)

but how do I replace the colon with 'h' and how do I insert a 'min' after the minutes?

And can someone explain this command sed 's/.*up \(.*\),.*user.*/\1/' to me?

Thanks a lot guys for the help! I appreciate it!

update:
my attempt at soving the problem looks like this

uptime | sed 's/.*up \(.*\),.*user.*/\1/' | awk '{sub(":", "h ", $0); sub(" ", "", $0); print "uptime:" $0}'

But I do not know how to insert a 'min' directly after the minutes and how I can get rid of the two white spaces in front of the ' xh' (x for the number of hours).