deallocvt - deallocate unused virtual terminals
deallocvt [__ ''N1 N2'' __...?
If given no argument, the program deallocvt
deallocates kernel memory and data structures for all unused
virtual terminals. If arguments Ni are given, only
TTY's /dev/ttyNi are deallocated.
A virtual terminal is unused if it is not the foreground
console, and no process has it open for reading or writing,
and no text has been selected on its screen.