egrep is Extended grep that supports added grep features like “+” (1 or more occurrence of previous character),”?”(0 or 1 occurrence of previous character) and “|” (alternate matching)
Arguments can be passed as: scriptName “Arg1” “Arg2”….”Argn” and can be accessed inside the script as $1 , $2 .. $n
Shell is a interface between user and the kernel. Even though there can be only one kernel ; a system can have many shell running simultaneously . Whenever a user enters a command through keyboard the shell communicates with the kernel to execute it and then display the output to the user.