ioctl.2

来自「<B>Digital的Unix操作系统VAX 4.2源码</B>」· 2 代码 · 共 82 行

.\" SCCSID: @(#)ioctl.2	8.1	9/11/90
.TH ioctl 2
.SH Name
ioctl \- control device
.SH Syntax
.nf
.ft B
#include <sys/ioctl.h>
.PP
.ft B
ioctl(d, request, argp)
int d, request;
char *argp;
.fi
.ft R
.SH Description
.NXR "file descriptor" "controlling"
.NXR "ioctl system call"
The
.PN ioctl
call performs a variety of functions
on open descriptors.  In particular, many operating
characteristics of character special files (for example, terminals)
can be controlled with 
.PN ioctl
requests.
Certain 
.PN ioctl
requests
operate on a number of device types. These include
informational 
.PN ioctl
requests, such as
.PN devio
and 
.PN nbuf .
The descriptions of various devices in the
.I Reference Pages, Section 4: Special Files
discuss how
.PN ioctl
applies to them. Also consult <sys/ioctl.h> 
for more information.
.PP
An 
.PN ioctl
.I request
has encoded in it whether the argument is an \*(lqin\*(rq parameter
or \*(lqout\*(rq parameter, 
and the size of the argument \fIargp\fP in bytes.
Macros and defines used in specifying an 
.PN ioctl
.I request
are located in the file <sys/ioctl.h>.
.SH Return Values
If an error has occurred, a value of \-1 is returned, and
.I errno
is set to indicate the error.
.SH Diagnostics
The
.PN ioctl
call fails under the following conditions:
.TP 15
[EBADF]
The \fId\fP is not a valid descriptor.
.TP 15
[ENOTTY]
The \fId\fP is not associated with a character
special device.
.TP 15
[ENOTTY]
The specified request does not apply to the kind
of object which the descriptor \fId\fP references.
.TP 15
[EINVAL]
The \fIrequest\fP or \fIargp\fP is not valid.
.TP 15
[EFAULT]
The \fIargp\fR points to memory that is not part of the process'
address space.
.SH See Also
execve(2), fcntl(2), devio(4), intro(4n), mu(4), nbuf(4), tty(4)