The REN (rename) command allows you to change the names of files. The file satisfying ufn2 is changed to ufn1.
The file Q.R is changed to X.Y.
The file XYZ.XXX is changed to XYZ.COM.
If ufn1 is already present, the REN command responds with the error Bad Name and does not perform the change. If ufn2 does not exist the message No File is printed at the console.