makedev(3) - Linux manual page (original) (raw)

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 _devt_.

   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)](../man2/mknod.2.html), 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)](../man2/stat.2.html).

ATTRIBUTES top

   For an explanation of the terms used in this section, see
   [attributes(7)](../man7/attributes.7.html).
   ┌──────────────────────────────────────┬───────────────┬─────────┐
   │ **Interface** │ **Attribute** │ **Value** │
   ├──────────────────────────────────────┼───────────────┼─────────┤
   │ **makedev**(), **major**(), **minor**()          │ Thread safety │ MT-Safe │
   └──────────────────────────────────────┴───────────────┴─────────┘

VERSIONS top

   The BSDs expose the definitions for these macros via
   _<sys/types.h>_.

STANDARDS top

   None.

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
   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 top

   [mknod(2)](../man2/mknod.2.html), [stat(2)](../man2/stat.2.html)

COLOPHON top

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Linux man-pages 6.10 2024-07-23 makedev(3)

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