Bash / Shell

Bash (Bourne Again Shell) is a command-line interpreter and scripting language. Brian Fox wrote it in 1989 for the GNU Project as a free replacement for the Bourne shell (sh). Bash is the default login shell on most Linux distributions and was the default on macOS until Catalina (10.15), when Apple switched to zsh. Chet Ramey has maintained the project since 1990.

The current release is Bash 5.2. As a shell, Bash provides job control, command-line editing, history, and programmable completion. As a scripting language, it supports variables, arrays, functions, arithmetic, conditionals, loops, and string manipulation. Bash scripts are widely used for system administration, CI/CD pipelines, build automation, and gluing together command-line tools. The language is POSIX-compatible with extensions — scripts that stick to POSIX sh syntax run on Bash, but Bash-specific features like arrays and [[ ]] test expressions require Bash specifically.

The GNU Bash manual is the authoritative reference for the language and built-in commands. The source code is available on the GNU Savannah repository under the GPL.