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makedev(3) [freebsd man page]

MAKEDEV(3)						   BSD Library Functions Manual 						MAKEDEV(3)

makedev, major, minor -- device number conversion SYNOPSIS
#include <sys/types.h> dev_t makedev(int major, int minor); int major(dev_t dev); int minor(dev_t dev); DESCRIPTION
The makedev() macro allows a unique device number to be generated based on its major and minor number. The major() and minor() macros can be used to obtain the original numbers from the device number dev. In previous implementations of FreeBSD all block and character devices were uniquely identified by a pair of major and minor numbers. The major number referred to a certain device class (e.g. disks, TTYs) while the minor number identified an instance within the device class. Later versions of FreeBSD automatically generate a unique device number for each character device visible in /dev/. These numbers are not divided in device classes. On FreeBSD these macros are only used by utilities that need to exchange numbers with other operating systems that may use different encod- ings for dev_t, but also applications that present these numbers to the user in a more conventional way. RETURN VALUES
The major() macro returns a device major number that has a value between 0 and 255. The minor() macro returns a device minor number whose value can span the complete range of an int. SEE ALSO
mknod(2), devname(3), devfs(5) BSD
September 28, 2008 BSD

Check Out this Related Man Page

MAKEDEV(3)						     Linux Programmer's Manual							MAKEDEV(3)

makedev, major, minor - manage a device number SYNOPSIS
#define _BSD_SOURCE #include <sys/types.h> dev_t makedev(int maj, int min); int major(dev_t dev); int minor(dev_t dev); DESCRIPTION
A device ID consists of two parts: a major ID, identifying the class of the device, and a minor ID, identifying a specific instance of a device in that class. A device ID is represented using the type dev_t. Given major and minor device IDs, makedev() combines these to produce a device ID, returned as the function result. This device ID can be given to mknod(2), for example. The major() and minor() functions perform the converse task: given a device ID, they return, respectively, the major and minor components. These macros can be useful to, for example, decompose the device IDs in the structure returned by stat(2). CONFORMING TO
The makedev() major() and minor() functions are not specified in POSIX.1, but are present on many other systems. NOTES
These interfaces are defined as macros. Since glibc 2.3.3, they have been aliases for three GNU-specific functions: gnu_dev_makedev(3), gnu_dev_major(3), and gnu_dev_minor(3). The latter names are exported, but the traditional names are more portable. SEE ALSO
mknod(2), stat(2) COLOPHON
This page is part of release 3.25 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at Linux 2008-12-01 MAKEDEV(3)
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