Unix Glossary

Browse 60 unix terms defined in plain English, from the cultural dictionary of computing.

60 Unix Terms

Awk
A classic Unix text-processing language and command-line tool used for filtering, transforming, and reporting on structured text streams. In slang usage,...
Bash
The Bourne Again Shell, the default command-line interpreter on most Linux distributions and macOS. Bash scripts are the glue of Unix system administration,...
Chmod
To change file or directory permissions on Unix-like systems using the `chmod` command. In casual engineering speech, people often use the command name as a...
chmod 777
A Unix command that makes a file or directory readable, writable, and executable by everyone, often used as a notorious example of a quick but unsafe...
Chroot Jail
A Unix isolation technique that changes a process's apparent root directory, restricting how it can access parts of the filesystem. Chroot jails provide...
Coreutils
The collection of fundamental GNU command-line utilities such as `ls`, `cp`, and `sort` that underpin many Unix-like workflows.
Cron Job
A scheduled task on Unix-like systems, configured via the crontab. The name comes from Chronos (Greek god of time). If you've ever wondered why something runs...
Crontab
The configuration file and command for managing cron jobs on Unix systems. The format uses five fields (minute, hour, day-of-month, month, day-of-week)...
Cut
In Prolog, the cut (!) operator commits to the current choice point, preventing backtracking past it. In Unix, the cut command extracts sections from each line...
Daemon
Daemon is a background process that runs continuously on a computer system without direct user interaction, performing system-level tasks or waiting to handle...
Dev Null
A reference to `/dev/null`, the Unix special file that discards anything written to it, often used figuratively for ignored messages, disappearing work, or...
Dotfile
A configuration file whose name starts with a dot (.), making it hidden in Unix directory listings. Examples include .gitignore, .bashrc, .env, and .eslintrc....
Fork Bomb
A denial-of-service pattern where processes recursively spawn more processes until the system exhausts its resources. The term is especially associated with...
GNU Coreutils
The GNU collection of essential command-line utilities such as `ls`, `cp`, `mv`, `cat`, and many others used across Unix-like systems. In open-source culture,...
Kill Dash Nine
A spoken version of `kill -9`, usually said with a tone that mixes practicality and violence. In engineering slang, it stands for the bluntest process...
Make
A build automation tool (originally from 1976) that reads dependency rules from a Makefile and executes only the commands needed to bring targets up to date,...
Makefile
A file containing rules, targets, dependencies, and shell commands read by the `make` utility to build a project. Each rule declares a target, its prerequisite...
Manpage
A manual page — the built-in documentation system on Unix-like systems, accessed via the 'man' command. The first and last resort for Unix questions, if you...
Man Page
Short for manual page, a command-line help document on Unix-like systems that describes a program, API, or system interface, usually accessed with the `man`...
Minicomputer
A mid-range computer class popular from the 1960s-1980s, smaller and cheaper than mainframes but more powerful than microcomputers. The PDP-11 and VAX were...
Multics
Multiplexed Information and Computing Service — an ambitious time-sharing operating system begun in 1964 that introduced hierarchical file systems, dynamic...
Named Pipe
A special file (FIFO) in the file system that enables unidirectional or bidirectional inter-process communication between unrelated processes on the same...
Neckbeard
A stereotype (sometimes self-applied with pride) of the deeply technical, socially awkward programmer — typically associated with Unix mastery, opinions about...
Neckbeard
A (self-deprecating) stereotype of an extremely knowledgeable but socially awkward programmer who uses Arch Linux, configures everything in the terminal, knows...
Pattern Action
A programming paradigm, most associated with AWK, where rules consist of a pattern (condition) paired with an action (code block). When input matches the...
Pipe
A mechanism for inter-process communication that connects the standard output of one process to the standard input of another, represented by the | character...
POSIX
Portable Operating System Interface — a family of IEEE standards (IEEE 1003) that define a common API, shell, and utility interface for Unix-like operating...
Process Group
A collection of one or more processes in a Unix-like OS that share a process group ID (PGID), allowing signals to be sent to the entire group at once. Process...
Redirection
The mechanism of sending a command's input or output to a file or another command instead of the default terminal. In Unix shells, > redirects stdout to a...
Root
The superuser account on Unix-like systems (UID 0) that has unrestricted access to all files, processes, and system calls. Also refers to the top-level node of...
Root Access
Administrative access with full control over a Unix-like system, allowing unrestricted changes to files, processes, and configuration. In practice it implies...
Root Access Security
The controls and practices used to protect root-level administrative access on Unix-like systems, including MFA, bastions, logging, least privilege, and...
Shebang
The #! character sequence at the beginning of a script file that tells the operating system which interpreter to use to execute it (e.g., #!/bin/bash,...
Shell
A command-line interpreter that reads user input (or scripts), parses it into commands, expands variables and globs, and executes programs — with common...
Shell Builtin
A command implemented directly inside the shell process rather than as a separate executable, either because it must modify the shell's own state (like `cd`,...
SIGKILL
Unix signal 9 — the unblockable, uncatchable signal that immediately terminates a process. When SIGTERM (the polite request to stop) is ignored, SIGKILL is the...
Signal Handler
A user-defined function registered with the operating system to execute when a process receives a specific signal (e.g., SIGTERM, SIGINT, SIGHUP). Because...
Socket
A software endpoint for bidirectional communication between two processes, identified by an IP address and port number for network sockets (TCP/UDP) or a...
Standard Error
The default output stream (file descriptor 2, or stderr) used by programs to emit error messages, warnings, and diagnostic information, separate from standard...
Standard Input
The default input stream (file descriptor 0, or stdin) from which a program reads data — typically the keyboard in an interactive terminal, or the output of...
Standard Output
The default output stream (file descriptor 1) to which a process writes its normal program output. In Unix-like systems, stdout is typically connected to the...
Stderr
Standard error (file descriptor 2) — the output stream reserved for error messages and diagnostic information. It is unbuffered by default and remains...
Stdin
Standard input (file descriptor 0) — the default input stream from which a process reads data, typically connected to the keyboard in an interactive session or...
Stdin/Stdout/Stderr
The three standard I/O streams in Unix: stdin (fd 0, input), stdout (fd 1, normal output), and stderr (fd 2, error output). The Unix philosophy of composing...
Stdout
Standard output (file descriptor 1) — the default output stream where a process writes its normal results. It is line-buffered when connected to a terminal and...
Sudo
Superuser Do — a Unix command that executes a command with elevated (root) privileges. In tech culture, used metaphorically: 'I sudo asked my boss for a...
Sudo Culture
The norms and attitudes around privileged access in Unix-like environments, including who gets it, how casually it is used, and whether escalation is treated...
Sudo Make Me a Sandwich
A classic xkcd-derived joke about privilege escalation, based on the idea that `sudo` can make almost any command permissible if you have the right rights. It...
Symbolic Link
A filesystem entry that contains a path reference to another file or directory rather than actual data. The OS transparently follows the link when accessed,...
Symlink
A symbolic link — a special file that acts as a pointer to another file or directory. Unlike hard links, symlinks can cross filesystems and point to...
Sysadmin Culture
The shared norms, humor, habits, and expectations of system administrators and infrastructure operators, including shell fluency, automation, incident...
TTY
Short for teletypewriter, a TTY is a terminal device interface in Unix-like systems that provides line-buffered, character-oriented I/O between a user and the...
Unix Beard
A humorous stereotype of the long-time Unix expert, often imagined as bearded, terminal-focused, and deeply knowledgeable about low-level systems. The phrase...
Unix Domain Socket
An inter-process communication mechanism on Unix-like systems that uses the socket API but communicates via a file path in the filesystem (e.g.,...
Unix Philosophy
A set of design principles originating from Ken Thompson and Dennis Ritchie's work at Bell Labs, emphasizing: write programs that do one thing well, write...
Unix Socket
A colloquial shorthand for Unix domain socket — an IPC endpoint identified by a filesystem path rather than an IP address and port. The socket file (e.g.,...
Vim
Vi IMproved — a highly configurable, modal text editor that's been a standard Unix tool since 1991. Famous for its steep learning curve and the enduring joke...
Vim vs Emacs
The long-running cultural rivalry between the text editors Vim and Emacs, often treated as a playful proxy for deeper preferences about tooling, extensibility,...
Worse Is Better
A software-design idea arguing that simpler, more pragmatic systems often win adoption over theoretically cleaner but more complex alternatives.
Zombie Process
Zombie Process is a process in a Unix-like operating system that has finished executing but still has an entry in the process table because its parent process...

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