Command to update the output of another command

If I have a team that each time gives me a result (for example, status). How can I do this to update this output every 2 seconds, for example ?. I remember that there is one team that does this. Example:

cat /proc/mdstat 

[======>..............]  resync = 30.8% (150544832/488383936) finish=65.8min speed=85472K/sec

othercommand cat /proc/mdstat

thank