If you simply want uptime formatted this small script will help.
uptime | awk -F'( |,|:)+' '{print $6,$7",",$8,"hours,",$9,"minutes."}'
Uptime by itself will display similar to:
20:25:48 up 3 days, 8:14, 1 user, load average: 2.07, 2.17, 2.35
Formatted using the code above will display similar to:
3 days, 8 hours, 15 minutes.
All information on this site is shared with the intention to help. Before any source code or program is ran on a production (non-development) system it is suggested you test it and fully understand what it is doing not just what it appears it is doing. I accept no responsibility for any damage you may do with this code.