Create a script that will allow the user to enter one of several choices from the command line. The specific requirements are as follows:

1. Copy one file to another. The user enters the source and destination file to copy to and from. The script shall handle the following cases:
a. Source file name specified does not exist. Script shall display an error message and terminate. Optionally, the script can display an error message and prompt the user to specify the source file name to copy from.
b. Source and destination files both exist. Script shall prompt for permission to overwrite the destination file. If permission is denied, program will display message and terminate.
c. Source file specified with no destination file specified. Script shall display error message and terminate or optionally, it can prompt the user to enter the file name to copy to.

2. Remove a file if it exists. The user provides the name of the file to remove or delete. Display a message indicating success or failure back to the user and terminates. The script shall handle the following conditions:
a. If the user enters the remove file option but no file name specified the script shall display an error message and terminate or, optionally, display an error message and prompt the user for the file name to remove and remove the file if it exists.
b. If the specified file does not exist the script shall display an error message and terminate.

3. Display the current day of the week. The script shall allow the user an option to display the day of the week.

4. Display the month's calendar. The script shall allow the user an option to display the month's calendar.

5. The script should be named commands.sh and accept options in the command line as either -r or -R for removing a file, -c or -C for copying a file, -d or –D to display the day of the week and –m or –M to display the month's calendar.

6. If the user enters command.sh without any options the script shall display the usage examples as shown below.

7. The script shall include the option and the necessary positional parameters information to perform the options as follows:

Copy a file:
prompt$ ./commands.sh –c sourceFile destinationFile
prompt$ ./commands.sh –C sourceFile destinationFile

Remove a file:
prompt$ ./commands.sh –r fileName
prompt$ ./commands.sh –r filename

Display day of week:
prompt$ ./commands.sh –d
prompt$ ./commands.sh –D

Display month's calendar:
prompt$ ./commands.sh –m
prompt$ ./commands.sh –M