Mount usb drive on raspberry
Plug In the USB drive
Create amount point
sudo mkdir /media/usb
sudo chown -R pi:pi /media/usb
Manually mount the device
sudo mount /dev/sda1 /media/usb -o uid=pi,gid=pi
Unmount the drive
sudo umount /media/usb
Auto mount (follow the link below for more information)
ls -l /dev/disk/by-uuid/
Find the UUID of the drive and add it in fstab file
sudo nano /etc/fstab
UUID= /media/usb vfat auto,nofail,noatime,users,rw,uid=pi,gid=pi 0 0
Use CTRL-X and y to save and exit the nano editor.
Source: https://www.raspberrypi-spy.co.uk/2014/05/how-to-mount-a-usb-flash-disk-on-the-raspberry-pi/