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  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 │
       └──────────────────────────────────────────────────────────────────────────────┴───────────────┴─────────┘

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)