bash
also: Bourne Again Shell, sh (when bash is invoked as sh), bash shell
Bash is the Bourne Again Shell, a command-line interpreter that reads and executes user commands and shell scripts on Linux and Unix systems. It's the default login shell on most Linux distributions.
Bash (Bourne Again Shell) is a Unix shell and command language that interprets commands typed by users or read from scripts. It's an improved version of the original Bourne shell (sh) and is the most widely used shell in Linux environments.
Bash provides interactive command execution, allowing users to run programs, manage files, and control system processes. When you open a terminal on Linux, you're typically using a bash shell. You can type commands like ls, cd, or grep directly at the prompt.
Bash also supports scripting—you can write sequences of commands in a text file (a bash script) and execute them as a program. For example, a script file backup.sh might contain multiple commands to automate system maintenance tasks. Scripts begin with a shebang line like #!/bin/bash to tell the system to use bash as the interpreter.
Beyond basic command execution, bash provides programming features including variables, loops, conditionals, functions, and I/O redirection, making it a powerful tool for system administration and automation.