useage="\nUseage: ./Lab_14.sh -i <infile> -o <outfile>\n -i <infile> The filename containing the existing data.\n -o <outfile> The
filename you want the output to go to."
options="\n\n Main Menu\n\n 1) Option 1\n 2) Option 2\n 3) Option 3\n 4) Option 4\n 5) Exit\n Please Select an Option from the
menu: "
selection=100 #setting the selection to a number so we dont run into errors
if [ "$#" == "0" ] #== means if arguments are = to 0
then
echo
echo "Error: No arguments present at all"
echo
echo -e $useage
exit 10 #sets error level to 10
fi
if [ "$1" != "-i" ] #if Variable 1 is not equal to -i
then
echo
echo "Error: Expecting \"-i\" for the first argument"
echo
echo -e $useage
exit 12
fi
if [ "$2" = "" ] #if Variable 2 is not equal to anything
then
echo
echo "Error: Second Argument is missing"
echo
echo -e $useage
exit 13
fi
if [ ! -e $2 ] #Checks to see if the file exists
then
echo
echo "Error: File Does not exist."
echo
echo -e $useage
exit 14
fi
if [ "$3" = "" ] #if there is nothing for 3rd variable is outputs this error
then
echo
echo "Error: Third Argument is missing"
echo
echo -e $useage
exit 15
fi
if [ "$3" != "-o" ] #if Variable 3 is not equal to -o it outputs this error
then
echo
echo "Error: Expecting \"-o\" for the third argument"
echo
echo -e $useage
exit 16
fi
if [ "$4" = "" ] #if Variable 4 is not equal to anything it outputs this error
then
echo
echo "Error: Fourth argument is missing"
echo
echo -e $useage
exit 17
fi
if [ $# \> 4 ] #Checks to see if the amount of arguments is grater than 4.
then
echo "Too many arguments provided on command line..."
echo -e $useage
exit 18
fi
if [ -e $4 ] #Checks to see if the file exists, if it does it asks if you wnat to overwrite or not
then
echo -e -n "\nMessage: File \"$4\" Already Exists. \nWould you like to overwrite the file? (y/n) "
read answer #loooks for the answer yes or no
case $answer in
y) echo -e "\nOverwrite Selected. Overwriting file...";;
n) echo -e "\nNo Overwtite Selected. Exiting the script..."
exit 19;;
*) echo -e "\nInvalid Input selected. Now exiting the script..."
exit 19;;
esac
else
until [ $selection = 5 ] #waits until the selection is 5 then exits the loop
do
case selection in
1) clear; echo -e -n $options #makes sure the script doesn't exit and waits for the user input.
read selection #reads the selection choosen by the user
echo -e "\\n Main Menu option \"$selection\" selected. \\n Press the <enter> key to continue..."; read;;
2) clear; echo -e -n $options
read selection
echo -e "\\n Main Menu option \"$selection\" selected. \\n Press the <enter> key to continue..."; read;;
3) clear; echo -e -n $options
read selection
echo -e "\\n Main Menu option \"$selection\" selected. \\n Press the <enter> key to continue..."; read;;
4) clear; echo -e -n $options
read selection
echo -e "\\n Main Menu option \"$selection\" selected. \\n Press the <enter> key to continue..."; read;;
*) clear; echo -e -n $options
read selection
echo -e "\\n Main Menu option \"$selection\" Not valid. You just crashed the script...."; read;;
exit 19;;
esac
clear
done
exit
fi
exit