A shell is the user interface in which you can do the following:
- Interact with the kernel, filesystem, and processes
- Execute programs, aliases, and shell built-ins
A shell provides extra features such as the following:
- Scripting
- Auto-completion
- History and aliasing
There are many different shells available, such as KornShell, Bash, and the Z-Shell. Bash is the default shell on almost every Linux system. Its development started in 1988 as a replacement for one of the oldest shells: the Bourne Shell. Based on Bourne and lessons learned from other shells such as KornShell and the C-shell, Bash has become the most popular shell and is available on many different operating systems including Windows 10, FreeBSD, macOS, and Linux.
The most important features that were added are as follows:
- Command-line editing
- History support
- Auto-completion
- Integer calculations ...