The command findmnt is used to find mounted filesystems in Linux. This command will look for a particular filesystem in /etc/fstab, /etc/mtab or /proc/self/mountinfo.

This article explains many of the options of the findmnt command.

Full article here:
Linux findmnt Command To Find Mounted Filesystems (LinOxide)
Related:
8 examples of findmnt command to check mounted file systems on Linux (BinaryTides)