Unix file system technology

special computer file that discards all writes

Linux kernel security module

defines the directory structure and directory contents in Linux operating systems

An inode (index node) is a data structure in a Unix-style file system that describes a file-system object such as a file or a directory. Each inode stores the attributes and disk block locations of the object's data. File-system object attributes may include metadata (times of last change, access, modification), as well as owner and permission data.

file system used by many Unix and Unix-like operating systems

abstract indicator (handle) used to access a file or other input/output resource

filesystem object containing a reference to another object by path

interface to a device driver that appears in a file system as if it were an ordinary file; e.g. /dev/* in Unix-like systems; CON, PRN, NUL in DOS/Windows

fstab (after file systems table) is a system file commonly found in the directory /etc on Unix and Unix-like computer systems. The /etc/fstab file is used by utilities from the util-linux package (such as mount and findmnt), but it's not limited to them — it is also processed by systemd via systemd-fstab-generator for automatic mounting during boot. The fstab file typically lists all available disk partitions and other types of file systems and data sources that may not necessarily be disk-based, and indicates how they are to be initialized or otherwise integrated into the larger file system s

is a special file in Unix-like operating systems that provides as many null characters (ASCII NUL, 0x00) as are read from it. One of the typical uses is to provide a character stream for initializing data storage.

thumb|upright=1.5|256 byte hex dump of In Unix-like operating systems, ' and ' are special files that provide random numbers from a cryptographically secure pseudorandom number generator (CSPRNG). The CSPRNG is seeded with entropy (a value that provides randomness) from environmental noise, collected from device drivers and other sources. Users can obtain random numbers from the CSPRNG simply by reading the file. Not all operating systems implement the same methods for and .

numeric value used in Unix-like operating systems to uniquely identify a user account

In Unix-like systems, the access rights flags setuid and setgid (short for set user identity and set group identity) allow users to run an executable with the file system permissions of the executable's owner or group respectively and to change behaviour in directories. They are often used to allow users on a computer system to run programs with temporarily elevated privileges to perform a specific task. While the assumed user id or group id privileges provided are not always elevated, at a minimum they are specific.

In Linux, FreeBSD, and NetBSD, , or the always-full device, is a special file that always returns the error code (meaning "No space left on device") on writing, and provides any number of zero bytes to a process that reads from it (similar to ). This device is usually used when testing the behavior of a program when it encounters a "disk full" error. $ echo "Hello, World" > /dev/full bash: echo: write error: No space left on device

The proc filesystem (procfs) is a special filesystem in Unix-like operating systems that presents information about processes and other system information in a hierarchical file-like structure, providing a more convenient and standardized method for dynamically accessing process data held in the kernel than traditional tracing methods or direct access to kernel memory. Typically, it is mapped to a mount point named /proc at boot time. The proc file system acts as an interface to internal data structures about running processes in the kernel. In Linux, it can also be used to obtain information

user ownership access right flag that can be assigned to files and directories on Unix-like systems

Unix/POSIX system account group number; numeric value used to represent a specific group

native file system of the Minix operating system

Unix device node that allows a file to be mounted as if it were a device

OverlayFS is a union mount filesystem implementation for Linux. It combines multiple different underlying mount points into one, resulting in a single directory structure that contains underlying files and sub-directories from all sources. Common applications overlay a read/write partition over a read-only partition, such as with LiveCDs and IoT devices with limited flash memory write cycles.

The mtab (mounted file systems table) file is a system information file, commonly found on Unix-like systems.

file types in Unix operating systems

directory structure used by a Unix-like operating system

Special kind of logical device to allow storage device to be accessed directly

defining feature of Unix, and its derivatives