mountpoint [-d|-q] directory | file
mountpoint -x device
mountpoint checks whether the given directory or file is mentioned in the /proc/self/mountinfo file.
Zero if the directory or file is a mountpoint, non-zero if not.
Karel Zak <email@example.com>
The util-linux mountpoint implementation was written from scratch for libmount. The original version for sysvinit suite was written by Miquel van Smoorenburg.
The mountpoint command is part of the util-linux package and is available from ftp://ftp.kernel.org/pub/linux/utils/util-linux/.