CommandLine

The command line, or command-line interface (CLI), refers to a text-based user interface for interacting with a computer. Users enter commands at a prompt to invoke programs, manage files, configure settings, and automate tasks. Unlike graphical user interfaces, the command line relies on precise syntax and options, with output typically displayed as text on the same console.

Most operating systems provide a command interpreter, or shell, which parses input, executes built-in commands, and optionally runs external programs. Common shells include Unix-like systems’ Bash, Zsh, and KornShell; Windows’ cmd.exe and PowerShell. Shells offer features such as variables, scripting, command history, aliases, tab completion, and job control.

Commands often support arguments and options, which modify behavior. Output can be redirected to files or devices and chained with pipes to pass data between commands. Global environment settings, such as PATH and other environment variables, influence command lookup and behavior. Scripting allows batch or automated tasks via script files (for example .sh, .bat, .ps1). Scheduling tools like cron or Task Scheduler can run scripts automatically.

Advantages of the command line include speed, repeatability, scripting capabilities, remote administration, and lower resource usage. Limitations include a steeper learning curve and potential risks from executing powerful commands. Cross-platform differences mean knowledge must be adapted to each environment.

Historically, command-line interfaces were the primary method of interaction with computers and remain central in system administration, development workflows, and automation. See also command-line interface, shell, terminal.