Shell Basics
Last updated
Last updated
A shell is a special user program that provides an interface for the user to use operating system services. Shell accepts human-readable commands from users and converts them into something which the kernel can understand.
It is a command language interpreter that executes commands read from input devices such as keyboards or from files. The shell gets started when the user logs in or starts the terminal.
Shell is broadly classified into two categories –
Command Line Shell
Graphical shell
Shell can be accessed by users using a command line interface. A special program called Terminal in Linux/macOS, or Command Prompt in Windows OS is provided to type in the human-readable commands.
Graphical shells provide means for manipulating programs based on the graphical user interface (GUI), by allowing for operations such as opening, closing, moving, and resizing windows, as well as switching focus between windows.
A program which is responsible for providing an interface to a user so that he/she can access the shell.
It basically allows users to enter commands and see the output of those commands in a text-based interface. Large scripts that are written to automate and perform complex tasks are executed in the terminal.
Usually, shells are interactive, which means they accept commands as input from users and execute them.
As a shell can also take commands as input from file, we can write these commands in a file and can execute them in shell to avoid this repetitive work. These files are called Shell Scripts or Shell Programs.
Each shell script is saved with `.sh` file extension e.g., myscript.sh.
A shell script has syntax just like any other programming language.
