Which command can be used to display all currently mounted filesystems?

The command that displays all currently mounted filesystems is found in the proc filesystem. By using cat /proc/self/mounts, you can read the current mount points along with pertinent information about each mounted filesystem, such as the device name, the mount point, the filesystem type, and various mount options. This file provides a live view of the mounts from the perspective of the current process.

The mount command also allows you to see currently mounted filesystems, but it is not as direct as reading the /proc file. It may display additional information or commands available for mounting and unmounting filesystems rather than simply listing them in a structured format.

Options such as free and lsmounts are not applicable for this task. The free command is specifically designed for displaying memory usage, while lsmounts is not a standard command on most Linux systems, which means it would not yield the desired output in this context. Thus, using the appropriate command from /proc is the most effective way to display all currently mounted filesystems on a Linux system.