Listing I/O Assignments

You can find out the current assignments for system and programmer logical units with the LISTIO command, which lists all the system or programmer logical units, even those that are unassigned. To list only currently assigned units, enter:
listio a
To find out the current assignment of one specific unit, for example SYS100, enter:
listio sys100
When you use the STAT option, LISTIO lists, for disk devices, whether the disk is read-only or read/write. For example, if you enter
listio sys100 (stat
you may receive the reply:
SYS100 B   R/W
This reply indicates that SYS100 is assigned to the B-disk, which is a read/write disk.
With the EXEC option of the LISTIO command, you can create a disk file containing the list of assignments. The name of the file is $LISTIO EXEC. It contains two EXEC numeric variables, &1 and &2, for each unit listed. For example, if you enter the command:
listio sys081 (exec
the file $LISTIO EXEC may contain the record:
&1 &2 SYS081 PRINTER
You can cancel all current assignments by leaving the CMS/DOS environment and then re-entering it:
set dos off
set dos on