Informing the utility/command which file or group of files to process (reading/writing of files).
Following script is used to print command line argument and will show you how to access them:
http://siber.cankaya.edu.tr/SystemsProgramming/cfiles/demodemo
#!/bin/sh
#
# Script that demos, command line args
#
echo "Total number of command line argument are $#"
echo "$0 is script name"
echo "$1 is first argument"
echo "$2 is second argument"
echo "All of them are :- $* or $@"