[thirdparty/man-pages.git] / man3 / makedev.3

.\" Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
.\"     <mtk.manpages@gmail.com>
.\"
.\" %%%LICENSE_START(VERBATIM)
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Permission is granted to copy and distribute modified versions of this
.\" manual under the conditions for verbatim copying, provided that the
.\" entire resulting derived work is distributed under the terms of a
.\" permission notice identical to this one.
.\"
.\" Since the Linux kernel and libraries are constantly changing, this
.\" manual page may be incorrect or out-of-date.  The author(s) assume no
.\" responsibility for errors or omissions, or for damages resulting from
.\" the use of the information contained herein.  The author(s) may not
.\" have taken the same level of care in the production of this manual,
.\" which is licensed free of charge, as they might when working
.\" professionally.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
.\" %%%LICENSE_END
.\"
.TH MAKEDEV 3 2014-05-28 "Linux" "Linux Programmer's Manual"
.SH NAME
makedev, major, minor \- manage a device number
.SH SYNOPSIS
.nf
.BR "#define _BSD_SOURCE" "             /* See feature_test_macros(7) */"
.B #include <sys/types.h>

.BI "dev_t makedev(unsigned int " maj ", unsigned int " min );

.BI "unsigned int major(dev_t " dev );
.BI "unsigned int minor(dev_t " dev );
.fi
.SH 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
.IR dev_t .

Given major and minor device IDs,
.BR makedev ()
combines these to produce a device ID, returned as the function result.
This device ID can be given to
.BR mknod (2),
for example.

The
.BR major ()
and
.BR 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
.BR stat (2).
.SH CONFORMING TO
The
.BR makedev (),
.BR major (),
and
.BR minor ()
functions are not specified in POSIX.1,
but are present on many other systems.
.\" The BSDs, HP-UX, Solaris, AIX, Irix
.SH NOTES
These interfaces are defined as macros.
Since glibc 2.3.3,
they have been aliases for three GNU-specific functions:
.BR gnu_dev_makedev (),
.BR gnu_dev_major (),
and
.BR gnu_dev_minor ().
The latter names are exported, but the traditional names are more portable.
.SH SEE ALSO
.BR mknod (2),
.BR stat (2)
Commit	Line	Data
47a0131a MK	1	.\" Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
	2	.\" <mtk.manpages@gmail.com>
	3	.\"
93015253	4	.\" %%%LICENSE_START(VERBATIM)
47a0131a MK	5	.\" Permission is granted to make and distribute verbatim copies of this
	6	.\" manual provided the copyright notice and this permission notice are
	7	.\" preserved on all copies.
	8	.\"
	9	.\" Permission is granted to copy and distribute modified versions of this
	10	.\" manual under the conditions for verbatim copying, provided that the
	11	.\" entire resulting derived work is distributed under the terms of a
	12	.\" permission notice identical to this one.
	13	.\"
	14	.\" Since the Linux kernel and libraries are constantly changing, this
	15	.\" manual page may be incorrect or out-of-date. The author(s) assume no
	16	.\" responsibility for errors or omissions, or for damages resulting from
	17	.\" the use of the information contained herein. The author(s) may not
	18	.\" have taken the same level of care in the production of this manual,
	19	.\" which is licensed free of charge, as they might when working
	20	.\" professionally.
	21	.\"
	22	.\" Formatted or processed versions of this manual, if unaccompanied by
	23	.\" the source, must acknowledge the copyright and authors of this work.
4b72fb64	24	.\" %%%LICENSE_END
47a0131a	25	.\"
8660ef9f	26	.TH MAKEDEV 3 2014-05-28 "Linux" "Linux Programmer's Manual"
47a0131a MK	27	.SH NAME
	28	makedev, major, minor \- manage a device number
	29	.SH SYNOPSIS
	30	.nf
86b91fdf	31	.BR "#define _BSD_SOURCE" " /* See feature_test_macros(7) */"
5f6f222a	32	.B #include <sys/types.h>
47a0131a	33
eb696b73	34	.BI "dev_t makedev(unsigned int " maj ", unsigned int " min );
47a0131a	35
2540aee7 MK	36	.BI "unsigned int major(dev_t " dev );
2540aee7 MK	37	.BI "unsigned int minor(dev_t " dev );
47a0131a	38	.fi
47a0131a MK	39	.SH DESCRIPTION
	40	A device ID consists of two parts:
	41	a major ID, identifying the class of the device,
	42	and a minor ID, identifying a specific instance of a device in that class.
	43	A device ID is represented using the type
	44	.IR dev_t .
	45
	46	Given major and minor device IDs,
	47	.BR makedev ()
	48	combines these to produce a device ID, returned as the function result.
	49	This device ID can be given to
	50	.BR mknod (2),
	51	for example.
	52
	53	The
	54	.BR major ()
	55	and
	56	.BR minor ()
	57	functions perform the converse task: given a device ID,
	58	they return, respectively, the major and minor components.
	59	These macros can be useful to, for example,
	60	decompose the device IDs in the structure returned by
	61	.BR stat (2).
47297adb	62	.SH CONFORMING TO
47a0131a	63	The
9afb166c MK	64	.BR makedev (),
9afb166c MK	65	.BR major (),
47a0131a MK	66	and
	67	.BR minor ()
	68	functions are not specified in POSIX.1,
	69	but are present on many other systems.
	70	.\" The BSDs, HP-UX, Solaris, AIX, Irix
	71	.SH NOTES
	72	These interfaces are defined as macros.
	73	Since glibc 2.3.3,
	74	they have been aliases for three GNU-specific functions:
27d47e71 MK	75	.BR gnu_dev_makedev (),
27d47e71 MK	76	.BR gnu_dev_major (),
47a0131a	77	and
27d47e71	78	.BR gnu_dev_minor ().
47a0131a	79	The latter names are exported, but the traditional names are more portable.
47297adb	80	.SH SEE ALSO
47a0131a MK	81	.BR mknod (2),
47a0131a MK	82	.BR stat (2)