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Operation

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MKNOD determines how to create the files based on the arguments passed to the program. When creating a device link or streams (character-type) file, you must enter both the major and minor numbers. To create a device link file, enter a major number of 0 and the LDEV number of the device as the minor number. To create a streams file, enter a major number greater than 0.

Syntax 

               mknod "name c|p major minor [link_name]"
Parameters
name

Creates a special or fifo file including the program name in the pathname.

c|p

Creates a device link file or streams file if this argument is 'c' (character type).

Creates a fifo file or pipe if this argument is 'p'.

major

Major number. The following major numbers are valid:

0

Creates a device link. The minor number represents the LDEV number.

1-254

Creates a streams file.

minor

Minor device type. This is used in conjunction with the major number option to provide a UNIX compatible device specification. The interpretion of the minor number is dependent on the value of the major number. If the major number is 0, then this number represents a LDEV number. If the major number is > 0, then this number represents a streams connection to a driver.

link_name

Creates the streams file with a link_name. This name is an eight-character MPE link_name (from the NMMGR link screen).

When the special file is created, it can be accessed through the HPFOPEN intrinsic and the C library "open" interface. The 0_NONBLOCK option can be specified using open.

MKNOD sets a CI variable mknodvar with the value 0 if successful. If errors occur, it returns the file system error status.

To create a fifo file called MYFIFO: 

   mknod "myfifo p"
To create a device link file for LDEV 7: 

   mknod "/dev/tape7 c,0,7"
To create a streams file with a link_name of DTSLINK, a major number of 1, and a minor number of 10: 

   mknod "strmfile c,1,10,dtslink"
You can use the LISTFILE command to display special files. For example: 

LISTFILE /dev/@,2

PATH= /dev/./

CODE  -------------LOGICAL RECORD----------------SPACE----- FILENAME
        SIZE  TYPE        EOF     LIMIT  R/B  SECTORS #X MX

        128W  FBf          0          1    1       0   0  * MYFIFO
        128W  FBs          0          1    1       0   0  * STRMFILE
        128W  FBd          0          1    1       0   0  * tape7

:LISTFILE /dev/tape7,5
**********************
FILE: /dev/tape7

FILE CODE : 0                  FOPTIONS: BINARY,FIXED,NOCCTL,DEVICE LINK
BLK FACTOR: 1                  OWNER   : **
REC SIZE: 256 (BYTES)          GROUP ID: **
BLK SIZE: 256 (BYTES)          SECURITY--READ   :
EXT SIZE: 0 (SECT)                       WRITE  :
NUM REC: 0                               APPEND :
NUM SEC: 0                               LOCK   :
NUM EXT: 0                               EXECUTE:
MAX REC: 1                             **SECURITY IS ON
                               FLAGS   : NO ACCESSORS
NUM LABELS: 0                  CREATED : THU, AUG 24, 1993 3:12 PM
MAX LABELS: 0                  MODIFIED: THU, AUG 24, 1993 3:12 PM
DISC DEV #: 1                  ACCESESED:THU, AUG 24, 1993 3:12 PM
SEC OFFSET: 0                  LABEL ADDR: **
VOLNAME   : MPEXL_SYSTEM_VOUME_SET:MEMBER1

DEV TYPE  : DEVICE LINK
LDEV      : 7                  IO CLASS: TAPE

Additional Discussion

For more information on streams and device link files, refer to the HPDEVCREATE intrinsic in the MPE/iX Intrinsics Reference Manual.



Chapter 14 MKNOD

Chapter 15 N7MF8CNV