makedev(3) — Linux manual page


makedev(3)              Library Functions Manual              makedev(3)

NAME         top

       makedev, major, minor - manage a device number

LIBRARY         top

       Standard C library (libc, -lc)

SYNOPSIS         top

       #include <sys/sysmacros.h>

       dev_t makedev(unsigned int maj, unsigned int min);

       unsigned int major(dev_t dev);
       unsigned int minor(dev_t dev);

DESCRIPTION         top

       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).

ATTRIBUTES         top

       For an explanation of the terms used in this section, see
       │ Interface                           Attribute     Value   │
       │ makedev(), major(), minor()         │ Thread safety │ MT-Safe │

VERSIONS         top

       The BSDs expose the definitions for these macros via

STANDARDS         top


HISTORY         top

       BSD, HP-UX, Solaris, AIX, Irix.

       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

       Depending on the version, glibc also exposes definitions for
       these macros from <sys/types.h> if suitable feature test macros
       are defined.  However, this behavior was deprecated in glibc
       2.25, and since glibc 2.28, <sys/types.h> no longer provides
       these definitions.

SEE ALSO         top

       mknod(2), stat(2)

COLOPHON         top

       This page is part of the man-pages (Linux kernel and C library
       user-space interface documentation) project.  Information about
       the project can be found at 
       ⟨⟩.  If you have a bug report
       for this manual page, see
       This page was obtained from the tarball man-pages-6.9.1.tar.gz
       fetched from
       ⟨⟩ on
       2024-06-26.  If you discover any rendering problems in this HTML
       version of the page, or you believe there is a better or more up-
       to-date source for the page, or you have corrections or
       improvements to the information in this COLOPHON (which is not
       part of the original manual page), send a mail to

Linux man-pages 6.9.1          2024-05-02                     makedev(3)

Pages that refer to this page: mknod(2)dev_t(3type)stat(3type)udev_device_new_from_syspath(3)