how to backup raspberry pi sd card to usb drive
Making a backup makes sense. But doing it all by hand makes less sense. What if you forget it? That’s exactly when you need it. 

So you automate the backup. For example, once a night, at a time when the system to be backed up has nothing to do.
Task

• Create a backup of your user directory “/ home/pi” on a USB stick.
• Create an executable script file that runs the backup.
• The backup should be created automatically every day at one o’clock.