#!/bin/bash
#
# backup-solution.sh - make a backup copy of all the .c files in current directory
#
# usage: backup-solution.sh
# (no arguments)
#
# input: none
# output: a line of confirmation for each file backed up
#
# Tim Pierson, Fall 2022

for i in *.c
do
  echo "backing up $i"
  # check if backup alredy exits
  if [ -f "$i.bak" ]; then
	  echo -e "\tback up already exists"
	  # back up exists, see if back up same as .c
	  diff "$i" "$i.bak" &>/dev/null #send diff output to /dev/null
	  if [ "$?" -ne 0 ]; then
		#not the same, make new back up
		echo -e "\tback up doesn't match .c, making new .bak file"
  		cp "$i" "$i.bak"
	  else
		echo -e "\tback up matches .c, making no changes"
	  fi
  else
	  echo -e "\tback up does not exist, making new .bak file"
	  cp "$i" "$i.bak"
  fi
done

exit 0