Explain the various programming maintenance tools in Unix operating system

i. command-line: It is the text interface that you used to interact with the shell.

ii. GNU: GNU is an acronym for GNU’s Not Unix. It is an organization founded by Richard Stallman. Many of the tools and bits of the Linux operating system were developed by GNU or under GNU’s public license.

iii. shell: It is a program that typically runs at each logged-in terminal which serves as the interpreter for user commands. The shell interprets a user’s command, and checks the validity and interfaces of the command with the kernel in executing the command.

iv. shell script: It is a file containing shell commands to perform a specific task. It is also called a shell program.