Shell Programming and Scripting

#! /bin/bash
echo "Beginning backup of files..."
# Check to see if files exist
if [ -f /home/user/Documents/backup.tar.gz ]; then
    read -p "Backup file already exists. Replace (y/n)?"
    [ "$REPLY" != "y" ] || tar -czf /home/user/Documents/backup.tar.gz /home/user/Documents/files
else
    tar -czf /home/user/Documents/backup.tar.gz /home/user/Documents/files
fi
echo "Backup complete."

#!/bin/bash
function yorn
{
   yn=""
   while [ "${yn}:" = ":" ]
   do
       printf "%s (y/n)? " "$1"
       read yn
       case $yn in
           [yY]|[Yy][Ee][Ss]) true;;
           [nN]|[nN][oO]) false;;
           *) yn="";;
       esac
  done
}
 
if [ ! -f /home/user/Documents/backup.tar.gz ] || yorn "Backup file already exists. Replace"
then
   tar -czf /home/user/Documents/backup.tar.gz /home/user/Documents/files
fi
echo "Backup complete."