udev /dev devtmpfs rw,mode=0755 0 0 devpts /dev/pts devpts rw,noexec,nosuid,gid=5,mode=0620 0 0 ... technically udev is responsible for device name into linux system, so it it fetched the unique identification from device and create a persistent rules sometime so whenever you reboot, or detach and attach the same device you'll get the same. Check filesystem type. Use any of the following commands to detect the filesystem type of a partition on your own Linux system. It's very easy to detect the filesystem type of a mounted partition with the df command and the -T (type) option. $ df -T Filesystem Type 1K-blocks Used Available Use% Mounted on udev devtmpfs 986848 0 986848 0% /dev.