mknod Post: 23660

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Top Forums UNIX for Dummies Questions & Answers mknod Post 23660 by killerserv on Wednesday 26th of June 2002 08:28:18 PM

06-26-2002

Registered User

In order to use mknod you need to know the major and minor node numbers for the device you wish to create. The devices.txt file in the kernel source documentation is the canonical source of this information.

To take an example, suppose that version of the MAKEDEV script does not know how to create the /dev/ttyS0 device file. Then you need to use mknod to create it. From looking at the devices.txt file that it should be a character device with major number 4 and minor number 64. So you now know all you need to create the file.

Exp:

Code:

	# mknod /dev/ttyS0 c 4 64
	# chown root.dialout /dev/ttyS0
	# chmod 0644 /dev/ttyS0
	# ls -l /dev/ttyS0
crw-rw----   1 root dialout    4,   64 Oct 23 18:23 /dev/ttyS0

As you can see, many more steps are required to create the file. In this example you can see the process required however

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mknod

mknod(5)							File Formats Manual							  mknod(5)

NAME

       mknod.h - header file of macros for handling device numbers

SYNOPSIS

DESCRIPTION

       The header file defines macros to create and interpret device identification numbers for use with the system call (see mknod(2)).

       The  use  of these macros is architecture-dependent.  See the System Administration Manual for your system for information on how to select
       major and minor device numbers.

       contains the macro

       which packs the major and minor components into a device identification number suitable for the dev argument of and the two macros:

       which extract the major and minor number components, respectively, from a device identification number, dev.

       The macro is a specification (see printf(3S)) that prints the minor number in the format best suited to the particular  implementation;	it
       is used by the long format of the command (see ls(1)) to show the minor numbers for device files.

       The  base of the number is indicated in the same way as in the C programming language: no leading zero for decimal, leading zero for octal,
       and leading for hexadecimal.

SEE ALSO

       ls(1), mknod(1M), mknod(2), printf(3S).

																	  mknod(5)