Where can you find the information about all mounted filesystems in Linux?

The information about all mounted filesystems in Linux can be found in the /proc/mounts file. This file contains a list of currently mounted filesystems, including details such as the device name, the mount point, the filesystem type, and mount options. It is dynamically generated by the kernel and reflects the current state of the system in real-time. This makes it a reliable source for checking which filesystems are active at any given moment.

The other choices represent different types of information related to storage but do not contain data about actively mounted filesystems. For instance, /proc/partitions provides details on the partitions recognized by the kernel, while /dev/disk/by-id and /dev/disk/by-label help identify disks and partitions by their unique identifiers or labels, respectively, rather than their mount status. Therefore, /proc/mounts is the authoritative location for understanding which filesystems are currently mounted on a Linux system.