Shell Glossary

Browse 18 shell terms defined in plain English, from the cultural dictionary of computing.

18 Shell Terms

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,...
Exit Code
A numeric value returned by a process to its parent when it terminates. By convention, 0 means success and any non-zero value indicates an error. Shell scripts...
Export
To make a function, variable, or class available for import by other modules. In JavaScript/TypeScript, 'export' controls the public API of a module. In shell...
Field Separator
A character or string used to delimit fields in a record. In Unix tools like AWK and cut, the field separator (FS or -d) determines how lines are split into...
Here Document
A type of string literal in shell scripting and several programming languages that preserves line breaks and allows embedding of multi-line text inline,...
One Liner
A command or piece of code compressed into a single line, usually for speed, cleverness, or convenience. Some one-liners are elegant; others become unreadable...
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...
PowerShell
Microsoft's task automation framework and command-line shell, built on .NET and designed around the concept of passing objects (not text) between commands....
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...
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 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`,...
Shell Expansion
The series of transformations the shell applies to a command line before execution — including brace expansion (`{a,b}`), tilde expansion (`~`),...
Shell Variable
A named value stored within the shell session, local to that shell process unless explicitly exported (at which point it becomes an environment variable...
Subshell
A child shell process spawned by the current shell to execute commands in an isolated environment, where variable changes and directory changes do not affect...
Tab Completion
A shell and editor feature that automatically completes partially typed commands, file paths, or variable names when the user presses the Tab key, using...
Terminal Emulator
A graphical application — such as iTerm2, Windows Terminal, Alacritty, or GNOME Terminal — that emulates a traditional hardware terminal by hosting a shell...
Variable Expansion
The shell mechanism that replaces a variable reference ($VAR or ${VAR}) with its value before executing a command. Supports default values (${VAR:-default}),...
Zsh
The Z Shell — an extended Bourne-compatible shell that became the default login shell on macOS starting with Catalina. It offers powerful features over bash...

Related Topics