Hi Michael, I extracted the below codes from lab4 and have put down the queries below (after long ______). Apologies as I am still figuring out how to use more interactive editing style (at least with some colors?).

#!/bin/bash

get file name from command line

check if file exists

if file doesn't exist, print error message

if [[ ! -f $1 ]] ______ why we put $1 here? $1 is the first argument? or what are we referring to? can we put $0? then 1>&2 echo ERROR ______ what does &2 here mean? exit 1 else # if file exists, print 3rd line head -n 3 $1 | tail -n 1 fi