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makedev(3) Library Functions Manual makedev(3)
makedev, major, minor - manage a device number
Standard C library (libc, -lc)
#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);
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).
For an explanation of the terms used in this section, see
attributes(7).
┌──────────────────────────────────────┬───────────────┬─────────┐
│ Interface │ Attribute │ Value │
├──────────────────────────────────────┼───────────────┼─────────┤
│ makedev(), major(), minor() │ Thread safety │ MT-Safe │
└──────────────────────────────────────┴───────────────┴─────────┘
The BSDs expose the definitions for these macros via
<sys/types.h>.
None.
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
portable.
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.
mknod(2), stat(2)
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
⟨⟩.
This page was obtained from the tarball man-pages-6.15.tar.gz
fetched from
⟨Linux man-pages 6.15 2025-05-17 makedev(3)
Pages that refer to this page: mknod(2), dev_t(3type), stat(3type), udev_device_new_from_syspath(3)
