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<H1>ioctl(2)</H1>
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<H2>NAME</H2><PRE>
ioctl - control device
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<H2>SYNOPSIS</H2><PRE>
<STRONG>#include</STRONG> <STRONG>&lt;sys/types.h&gt;</STRONG>
<STRONG>#include</STRONG> <STRONG>&lt;sys/ioctl.h&gt;</STRONG>
<STRONG>int</STRONG> <STRONG>ioctl(int</STRONG> <EM>d</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>request</EM><STRONG>,</STRONG> <STRONG>void</STRONG> <STRONG>*</STRONG><EM>argp</EM><STRONG>)</STRONG> <STRONG>(Minix)</STRONG>
<STRONG>int</STRONG> <STRONG>ioctl(int</STRONG> <EM>d</EM><STRONG>,</STRONG> <STRONG>ioreq_t</STRONG> <EM>request</EM><STRONG>,</STRONG> <STRONG>void</STRONG> <STRONG>*</STRONG><EM>argp</EM><STRONG>)</STRONG> <STRONG>(Minix</STRONG>-<STRONG>vmd)</STRONG>
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<H2>DESCRIPTION</H2><PRE>
<STRONG>Ioctl</STRONG> performs a variety of functions on open descriptors. In
particular, many operating characteristics of character special files
(e.g. terminals) may be controlled with <STRONG>ioctl</STRONG> requests. The writeups of
various devices in section 4 discuss how <STRONG>ioctl</STRONG> applies to them.
An ioctl <EM>request</EM> has encoded in it whether the argument is an "in"
parameter or "out" parameter, and the size of the argument <EM>argp</EM> in bytes.
Macros and defines used in specifying an ioctl <EM>request</EM> are located in the
file &lt;<EM>sys</EM>/<EM>ioctl</EM>.<EM>h</EM>&gt;.
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<H2>RETURN VALUE</H2><PRE>
If an error has occurred, a value of -1 is returned and <STRONG>errno</STRONG> is set to
indicate the error.
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<H2>ERRORS</H2><PRE>
<STRONG>Ioctl</STRONG> will fail if one or more of the following are true:
[EBADF] <EM>D</EM> is not a valid descriptor.
[ENOTTY] <EM>D</EM> is not associated with a character special device.
[ENOTTY] The specified request does not apply to the kind of object
that the descriptor <EM>d</EM> references.
[EINVAL] <EM>Request</EM> or <EM>argp</EM> is not valid.
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<H2>SEE ALSO</H2><PRE>
<STRONG><A HREF="../man2/execve.2.html">execve(2)</A></STRONG>, <STRONG><A HREF="../man2/fcntl.2.html">fcntl(2)</A></STRONG>, <STRONG><A HREF="../man4/mt.4.html">mt(4)</A></STRONG>, <STRONG><A HREF="../man4/tty.4.html">tty(4)</A></STRONG>, <STRONG><A HREF="../man4/intro.4.html">intro(4)</A></STRONG>.
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