What is a command shell?

A program that interprets commands, is a way to interface with the operating system and run commands.

How to write a shell script?

a$.$ Use any editor like vi$,$ vim, pico, or mcedit to write a shell script.

b$.$ After writingthe shell script set execute permission for your script as follows:

Examples:

$ chmod $+x$ your$-$script$-$name

$ chmod $755$ your$-$script$-$name

Try the following shell then print the result:

Save the file and know we should give the access permission as follow :

'Explain each line in the script?.

Exercise: Write the following shell script, save it$,$ execute it and note down its output: