In this recitation, you will write a BASH script which will backup a directory, keeping only the last N days of backups (default 5). Your script should be able to change this value via the command-line.

The skills that you will demonstrate:

• Ability to write a bash program
• Ability to access command-line arguments
• Ability to run programs from your script and capture the output
• Ability to use tar and gzip to pack a directory into a compressed file

Complete the following tasks. You may receive guidance from your instructor or other students. All code that you submit should be written by you.

1. Obtain the name of the directory from the command line as a required parameter.
2. Check for an optional switch and parameter (-t ) which will override the default retention
3. Calculate the name of the backup file based on the directory and the date. Ex: src_2020_01_27
4. Use tar cvfz
   to pack and compress your directory and place in a backup directory.
5. Remove any files older than N days from the backup directory.

Some useful hints:

1. The date program can output in any format. Try date +%Y for an example
2. In your script you can capture the output of command lines in reverse quotes `date`
3. Your output filename should be built up as a string by concatenation
4. The find command can delete certain files. Look at -mtime and -delete switches.

Requirements:

• Your program should be named backup.sh without the quotes.
• You should include your name and EUID in a comment at the top of the file
• Your program should use the bash shell
• The optional switch -t will take a numeric argument in days
• The default retention is 5 days
• Create a new directory of your choice to hold backups
• Your program will be graded largely on whether is works correctly on the CSE machines (e.g. cse01, cse02, , cse06) so you should make sure that your program compiles and runs correctly on one of these machines.