Cmdline

Cmdline, short for command line, refers to a text-based interface for interacting with a computer system. In a cmdline session a command-line interpreter or shell reads user input, parses it into a command, options, and arguments, and executes the corresponding program or internal operation. This interface is used for system administration, automation, software development, and troubleshooting.

Commands are issued as text strings. They may be built into the shell or external programs. Options or flags modify command behavior, and arguments supply data such as filenames or parameters. Features often include pipelines that connect the output of one program to the input of another, and redirection that sends output to files or devices. Shells may support variables, conditionals, loops, and basic scripting constructs to automate tasks.

Common shells and environments vary by platform. Windows provides cmd.exe and PowerShell; Unix-like systems use sh, Bash, Zsh, and others. Each shell has its own syntax and built-ins, though many concepts are shared. Scripting is a major use case: batch files in Windows, shell scripts in Unix-like systems, and PowerShell scripts on Windows and cross-platform environments. Third-party scripting languages such as Python or Ruby are also used to implement complex command-line workflows.

Advantages of the cmdline include precision, scriptability, and strong support for automation and remote management. Limitations include a steeper learning curve compared with graphical interfaces and fragmentation across platforms. Security considerations center on executing trusted commands, validating input, and following principle-of-least-privilege practices to minimize risk.

Related concepts include command-line interfaces (CLI), shells, terminal emulators, and text-based scripting.