USB flash drive
ESOS is a niche Linux distribution. ESOS is intended to run on a USB flash drive, or some other type of removable media such as Secure Digital, CompactFlash, etc. ESOS is a memory resident operating system: At boot, a tmpfs file system is initialized as the root file system and the USB flash drive image is copied onto this file system. Configuration files and logs are periodically written to a USB flash drive (persistent storage) or by user intervention when configuration changes occur.