1. What do you understand by a shell? and why is it needed? 2. Is there similarity between Unix and Linux, demonstrate based on historical background. 3. Differentiate between $ and # in shell script. 4. With example describe the shell command syntax. 5. Name the alternative command for echo. 6. Describe key component of Linux Operating Systems. 7. What is the alternative to if-else statements in shell scripting? 8. Write a short script to describe check weather the given file exists