1.\" $NetBSD: makedev.3,v 1.2 2011/04/01 06:03:06 jruoho Exp $ 2.\" 3.\" Copyright (c) 2008 Ed Schouten <ed@FreeBSD.org> 4.\" All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 15.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25.\" SUCH DAMAGE. 26.\" 27.\" $FreeBSD: src/share/man/man3/makedev.3,v 1.2 2008/09/28 20:26:16 ed Exp $ 28.\" 29.Dd April 1, 2011 30.Dt MAKEDEV 3 31.Os 32.Sh NAME 33.Nm makedev , 34.Nm major , 35.Nm minor 36.Nd device number conversion 37.Sh SYNOPSIS 38.In sys/types.h 39.Ft dev_t 40.Fn makedev "int major" "int minor" 41.Ft int 42.Fn major "dev_t dev" 43.Ft int 44.Fn minor "dev_t dev" 45.Sh DESCRIPTION 46The 47.Fn makedev 48macro allows a unique device number to be generated based on its 49.Fa major 50and 51.Fa minor 52number. 53The 54.Fn major 55and 56.Fn minor 57macros can be used to obtain the original numbers from the device number 58.Fa dev . 59.Pp 60All block and character devices are uniquely 61identified by a pair of major and minor numbers. 62The major number refers to a certain device class (e.g. disks, TTYs) 63while the minor number identifies an instance within the device class. 64.Sh RETURN VALUES 65The 66.Fn major 67macro returns a device major number that has a value between 0 and 255. 68The 69.Fn minor 70macro returns a device minor number whose value can span the complete 71range of an 72.Vt int . 73.Sh SEE ALSO 74.Xr mknod 2 , 75.Xr devname 3 , 76.Xr MAKEDEV 8 77