Returns the device names of all devices on a system that meet the
    specified selection criteria.

    Note that the device names are returned in random order.

    Format

      F$DEVICE([search_devnam],[devclass],[devtype], [stream-id])

1  –  Return Value

    A character string containing the name of a device in the
    system's list of devices. After the last device name in the
    system's device list is returned, the F$DEVICE function returns a
    null string ("").

2  –  Arguments

 search_devnam

    Specifies the name of the device for which F$DEVICE is to search.
    The asterisk (*)  and the percent sign (%) wildcard characters
    are allowed in the search_devnam argument.

    Specify the search_devnam argument as a character string
    expression.

 devclass

    Specifies the device class for which F$DEVICE is to search.
    Specify the devclass argument as a character string expression
    that corresponds to a valid device class name.

    See the DVI$_DEVCLASS item in the $GETDVI system service for
    additional information.

 devtype

    Specifies the device type for which F$DEVICE is to search.
    Specify the devtype argument as a character string expression
    that corresponds to a valid type name.

    See the DVI$_DEVTYPE item in the $GETDVI system service for
    additional information.

                                   NOTE

       Specifying a device type without specifying a device class
       will result in an error.

 stream-id

    A positive integer representing the search stream identification
    number.

    The search stream identification number is used to maintain
    separate search contexts when you use the F$DEVICE function more
    than once and when you supply different search criteria. If you
    use the F$DEVICE function more than once in a command procedure
    and if you also use different search criteria, specify stream-id
    arguments to identify each search separately.

    If the search criteria are changed in a call before the device
    name list is exhausted, the context will be reinitialized and the
    search will restart.

    If you omit the stream-id argument, the F$DEVICE function assumes
    an implicit single search stream. That is, the F$DEVICE function
    starts searching at the beginning each time you specify different
    search criteria.

3  –  Example

  $ START:
  $     DEVICE_NAME = F$DEVICE("*0:","DISK","RA60")
  $     IF DEVICE_NAME .EQS. "" THEN EXIT
  $     SHOW SYMBOL DEVICE_NAME
  $     GOTO START

      This command procedure displays the device names of all the
      RA60s on a unit numbered 0.

      Because no stream-id argument is specified, F$DEVICE uses an
      implicit search stream. Each subsequent use of the F$DEVICE
      function uses the same search criteria to return the next
      device name. After the last device name is displayed, the
      F$DEVICE function returns a null string and the procedure
      exits.