Mount A USB Memory Stick / Drive
List available devices
ls -l /dev/disk/by-uuid/
SDA1 will be your USB memory stick (unless you have multiple). What it means:
The SD means SCSI device which also incoporates USB drives.
The A means the 1st drive found (the next would be SDB, SDC, etc)
The 1 means the first partition of the device (multiple partitions will give SDA2, SDA3, etc)
Create a directory to assign it to and apply ownership of it
Note that "usb" can be anything you want,
sudo mkdir /media/usb sudo chown -R pi:pi /media/usb
Mount the USB Drive
sudo mount /dev/sda1 /media/usb -o uid=pi,gid=pi
You can now access your drive using the path /media/usb/
Un-mount the USB drive
sudo umount /media/usb
E.g. if you want to remove it before the RPi is powered down