centos man page for major

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

NAME
       makedev, major, minor - manage a device number

SYNOPSIS
       #define _BSD_SOURCE	       /* See feature_test_macros(7) */
       #include <sys/types.h>

       dev_t makedev(int maj, int min);

       unsigned int major(dev_t dev);
       unsigned 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(),
       gnu_dev_major(), and gnu_dev_minor().  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 3.53 of the Linux man-pages project.  A description of the project, and information about reporting bugs, can
       be found at http://www.kernel.org/doc/man-pages/.

Linux								    2012-05-10								MAKEDEV(3)