How to test if a given path is a mount point

Question

Suppose do you want test if /mnt/disk is a mount point in a shell script. How do you do this?

Answer 1

Here is a variant with "df -P" which is supposed to be portable:

mat@owiowi:/tmp$ f(){ df -P  | awk '{ if($6 == "'$1'")print   }' ; }
mat@owiowi:/tmp$ f /
/dev/mapper/lvm0-vol1  20642428  17141492   2452360      88% /
mat@owiowi:/tmp$ f /mnt
mat@owiowi:/tmp$ f /mnt/media
/dev/mapper/lvm0-media  41954040  34509868   7444172      83% /mnt/media