I want to limit the percentage of CPU a user who ssh to my comp can use like say only 25% cpu usage at max. How do i do this in ubuntu ?
I think you can't do that. What you can do is modifying priority for user. You can do that by editing file
Sets priority for john's processes to 20 (effective after next login). 20 is lowest priority.
This way john can use 100% of CPU, but if someone else needs it, other user will immediately get it, and john's tasks will wait (or actually slow down, not stop completely).