Jump to content United States-English
HP.com Home Products and Services Support and Drivers Solutions How to Buy
» Contact HP
More options
HP.com home
HP-UX Reference > M


HP-UX 11i Version 3: February 2007

Technical documentation

» Feedback
Content starts here

 » Table of Contents

 » Index


mknod — create special files


/sbin/mknod name c major minor

/sbin/mknod name b major minor

/sbin/mknod name p


The mknod command creates the following types of files:

  • Character device special file (first SYNOPSIS form),

  • Block device special file (second SYNOPSIS form),

  • FIFO file, sometimes called a named pipe (third SYNOPSIS form).

name is the path name of the file to be created. The newly created file has a default mode that is readable and writable by all users (0666), but the mode is modified by the current setting of the user's file mode creation mask (see umask(1)).

Character and Block Special Files

Character device special files are used for devices that can transfer single bytes at a time, such as nine-track magnetic tape drives, printers, plotters, disk drives operating in "raw" mode, and terminals. To create a character special file, use the c argument.

Block device special files are used for devices that usually transfer a block of data at a time, such as disk drives. To create a block device special file, use the b argument.

The remaining arguments specify the device that will be accessible through the new special file:


The major number specifies the major device type (for example, the device driver number).


The minor number specifies the device location, which is typically, but not always, the unit, drive, and/or line number.

The major and minor values can each be specified in hexadecimal, octal, or decimal, using C language conventions (decimal: no leading zero; octal: leading zero; hexadecimal: leading 0x).

The assignment of major and minor device numbers is specific to each HP-UX system. Refer to the System Administrator manuals supplied with your system for details.

Only users who have appropriate privileges can use mknod to create a character or block device special file.

FIFO files

To create a FIFO (named pipe or buffer) file, use the p argument. You can also use the mkfifo command for this purpose (see mkfifo(1)). All users can use mknod to create FIFO files.


Access Control Lists

In HFS file systems, optional ACL entries can be added to special files and FIFOs with the chacl command (see chacl(1)). In JFS file systems, optional ACL entries can be added to special files and FIFOs with the setacl command (see setacl(1)). However, system programs are likely to silently change or eliminate the optional ACL entries for these files.


chacl(1), mkdir(1), mkfifo(1), setacl(1), umask(1), lsdev(1M), sam(1M), mknod(2), acl(5), aclv(5), mknod(5).

HP-UX System Administrator manuals


mknod: SVID2, SVID3, XPG2

Printable version
Privacy statement Using this site means you accept its terms Feedback to webmaster
© 1983-2007 Hewlett-Packard Development Company, L.P.