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(unsigned int maj, unsigned 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  rep‐
       resented 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 3.74 of the Linux man-pages project.  A description of the
       project, information about reporting bugs, and the latest version of  this  page,  can  be
       found at http://www.kernel.org/doc/man-pages/.



Linux                                       2014-05-28                                 MAKEDEV(3)