The nodev mount option specifies that the filesystem cannot contain special devices. Rationale: Since the /dev/shm filesystem is not intended to support devices, set this option to ensure that users cannot attempt to create special devices in /dev/shm partitions.
Edit the /etc/fstab file and add nodev to the fourth field (mounting options) for the /dev/shm partition. See the fstab(5) manual page for more information. Run the following command to remount /dev/shm : # mount -o remount,nodev /dev/shm References: https://manpages.debian.org/buster/initscripts/tmpfs.5.en.html Notes: The setting in /etc/default/rcS, if present, will still be used, but the setting in /etc/default/tmpfs will take precedence if enabled. If desired, the defaults may also be overridden with an entry in in /etc/fstab /run/shm was previously /dev/shm, and a compatibility symlink or bind mount will be created to allow the old path to continue to function. If an fstab entry for /dev/shm exists instead of /run/shm, then /dev/shm will continue to be used.