"Everything is a file" describes one of the defining features of Unix, and its derivatives — that a wide range of input/output resources such as documents, directories, hard-drives, modems, keyboards, printers and even some inter-process and network communications are simple streams of bytes exposed through the filesystem name space.
In computing, a file system or filesystem controls how data is stored and retrieved.
A hard disk drive (HDD), hard disk, hard drive or fixed disk is an electromechanical data storage device that uses magnetic storage to store and retrieve digital information using one or more rigid rapidly rotating disks (platters) coated with magnetic material.
The inode is a data structure in a Unix-style file system that describes a filesystem object such as a file or a directory.
A journaling file system is a file system that keeps track of changes not yet committed to the file system's main part by recording the intentions of such changes in a data structure known as a "journal", which is usually a circular log.
In computing, a page cache, sometimes also called disk cache, is a transparent cache for the pages originating from a secondary storage device such as a hard disk drive (HDD).
Plan 9 from Bell Labs is a distributed operating system, originating in the Computing Sciences Research Center (CSRC) at Bell Labs in the mid-1980s, and building on UNIX concepts first developed there in the late 1960s; until the Labs' final release at the start of 2015.
A power outage (also called a power cut, a power out, a power blackout, power failure or a blackout) is a short-term or a long-term loss of the electric power to a particular area.
QNX is a commercial Unix-like real-time operating system, aimed primarily at the embedded systems market.
Soft updates is an approach to maintaining file system meta-data integrity in the event of a crash or power outage.
The Unix philosophy, originated by Ken Thompson, is a set of cultural norms and philosophical approaches to minimalist, modular software development.
Volatile memory, in contrast to non-volatile memory, is computer memory that requires power to maintain the stored information; it retains its contents while powered on but when the power is interrupted, the stored data is quickly lost.