This article helps to resolve the issue of "mkdir: /var/tmp/usb File exists"  message seen while creating a directory for the USB drive to mount.

While creating a directory to mount the USB the "File exists" message is seen. 

root@switch% mkdir /var/tmp/usb
mkdir: /var/tmp/usb File exists

This message indicates that the directory named usb is already present in /var/tmp directory. 

Either create a new directory to mount the usb drive or use the existing usb directory. 

Creating a new directory USB

root@switch% mkdir /var/tmp/USB
root@switch%
 

Note: No message in next line indicates that the USB directory is created successfully.