Section: Linux Programmer's Manual (3)
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makedev, major, minor - manage a device number
#define _BSD_SOURCE /* See feature_test_macros(7) */
dev_t makedev(int maj, int min);
int major(dev_t dev);
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
Given major and minor device IDs,
combines these to produce a device ID, returned as the function result.
This device ID can be given to
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
functions are not specified in POSIX.1,
but are present on many other systems.
These interfaces are defined as macros.
Since glibc 2.3.3,
they have been aliases for three GNU-specific functions:
The latter names are exported, but the traditional names are more portable.
This page is part of release 3.27 of the Linux
A description of the project,
and information about reporting bugs,
can be found at
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This document was created by
using the manual pages.