system call invalidates all current open file descriptors in the system
for the file named by
Subsequent operations on any such descriptors
fail, with the exceptions that a
from a character device file which has been revoked
returns a count of zero (end of file),
system call will succeed.
If the file is a special file for a device which is open,
the device close function
is called as if all open references to the file had been closed
using a special close method which does not block.
Access to a file may be revoked only by its owner or the super user.
system call is currently supported only for block and character special
It is normally used to prepare a terminal device for a new login session,
preventing any access by a previous user of the terminal.