NAME

       makedev, major, minor - manage a device number

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  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

       For an explanation of the terms used in this section, see attributes(7).

       ┌────────────────────────────┬───────────────┬─────────┐
       │Interface                   │ Attribute     │ Value   │
       ├────────────────────────────┼───────────────┼─────────┤
       │makedev(), major(), minor() │ Thread safety │ MT-Safe │
       └────────────────────────────┴───────────────┴─────────┘

CONFORMING TO

       The makedev(), major(), and minor() functions  are  not  specified  in  POSIX.1,  but  are
       present on many other systems.

NOTES

       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.

       The  BSDs  expose  the  definitions  for these macros via <sys/types.h>.  Depending on the
       version, glibc also exposes definitions for these macros from that header file 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)

COLOPHON

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