“Bash” stands for “Bourne-Again SHell,” and it is a widely used command-line interpreter for Unix-like operating systems. It is designed as an enhanced replacement for the original Bourne shell (sh) and is compatible with the sh syntax. Bash is the default shell on many Linux distributions and is also available on other Unix-based systems.
As a command-line interpreter, Bash provides a text-based interface through which users can interact with the operating system. It reads commands entered by the user and executes them, providing the corresponding output or performing the desired operations.
Bash offers a comprehensive set of features and capabilities that make it a powerful and flexible tool for command-line operations. It supports various functionalities, including command execution, variable handling, flow control (such as loops and conditionals), command substitution, I/O redirection, and process control. It also provides features like history management, command-line editing, and programmable completion, which enhance usability and productivity.
Being an sh-compatible shell, Bash supports most of the sh syntax and commands. This means that scripts and commands written for the Bourne shell (sh) can generally be executed by Bash without modifications. However, Bash extends the capabilities of the Bourne shell and introduces additional features, such as arrays, associative arrays, and improved command-line editing.
Bash also includes a set of built-in commands and utilities that can be executed directly from the shell prompt, without relying on external programs. These built-in commands provide functionalities like file manipulation, string manipulation, arithmetic operations, and more.
In addition to being a command-line interpreter, Bash is also a scripting language. It allows users to write shell scripts, which are collections of commands and instructions that can be executed sequentially or conditionally. Shell scripting with Bash is widely used for automating tasks, creating complex workflows, and developing system administration scripts.
bash Command Examples
1. Start an interactive shell session:
2. Start an interactive shell session without loading startup configs:
# bash --norc
3. Execute specific [c]ommands:
# bash -c "echo 'bash is executed'"
4. Execute a specific script:
# bash /path/to/script.sh
5. Execute a specific script while printing each command before executing it:
# bash -x /path/to/script.sh
6. Execute a specific script and stop at the first [e]rror:
# bash -e /path/to/script.sh
7. Execute specific commands from stdin:
# echo "echo 'bash is executed'" | bash
Overall, Bash is a powerful and versatile shell and command-line interpreter. It provides a rich set of features, compatibility with the sh syntax, and the ability to execute both interactive commands and shell scripts. With its extensive capabilities, Bash is a fundamental tool for Unix-like systems and is widely utilized by system administrators, developers, and power users for various command-line operations and automation tasks.