/OUTPUT=filespec

    Specifies the output file to which the results of the SPAWN
    operation are written. No wildcards can be used in the file
    specification. (Do not specify SYS$COMMAND as a file
    specification for the /OUTPUT qualifier when using the /NOWAIT qualifier;
    both parent and subprocess output will be displayed simultaneously
    on your terminal.)

    You cannot explicitly specify non-record-oriented, process-
    permanent files (NRO PPFs) with the /OUTPUT qualifier. The system
    displays an error message when it encounters such a file as the
    value for the /OUTPUT qualifier.

    Note that when NRO PPFs are used as implicit output, the SPAWN
    command can succeed, as shown in the following table:

    Process Type   SYS$OUTPUT     Implicit Output

    Any            NRO PPF        Mailbox transmitting records for
    parent to write to its current
    SYS$OUTPUT device

    Any            Any other      SYS$OUTPUT

    If you omit the /OUTPUT qualifier, output is written to the
    current SYS$OUTPUT device.