makedev(3) Library Functions Manual makedev(3)
NAME
makedev, major, minor - manage a device number
LIBRARY
Standard C library (libc, -lc)
SYNOPSIS
#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
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 de-
vice 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
For an explanation of the terms used in this section, see attributes(7).
┌────────────────────────────────────────────┬───────────────┬─────────┐
│ Interface │ Attribute │ Value │
├────────────────────────────────────────────┼───────────────┼─────────┤
│ makedev(), major(), minor() │ Thread safety │ MT-Safe │
└────────────────────────────────────────────┴───────────────┴─────────┘
VERSIONS
The BSDs expose the definitions for these macros via <sys/types.h>.
STANDARDS
None.
HISTORY
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.
SEE ALSO
mknod(2), stat(2)
Linux man-pages 6.9.1 2024-05-02 makedev(3)
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