Question: how to transfer file from usb to linux?
Answer: You can simply use cp command to copy files.Usually any media will be mounted in /media/nameofusb/. inorder to copy a file you can use. cp. ... 
That is unusual.But you can try to remount the usb as rw as superuser by this command. mount -o remount,rw /dev/sdb1. here my device is sdb1. ... 
You should see something like this.