When should I use /dev/shm/ and when should I use /tmp/?

is a temporary file storage filesystem, i.e., tmpfs, that uses RAM for the backing store. It can function as a shared memory implementation that facilitates IPC. From Wikipedia: Recent 2.6 Linux kernel builds have started to offer /dev/shm as shared memory in the form of a ramdisk, more specifically as a world-writable directory that is stored in memory with a defined limit in /etc/default/tmpfs. /dev/shm support is completely optional within the kernel config file. It is included by default in…