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IOCTL(2)                  FreeBSD System Calls Manual                 IOCTL(2)

NAME
     ioctl - control device

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <sys/ioctl.h>

     int
     ioctl(int d, unsigned long request, ...);

DESCRIPTION
     The ioctl() function manipulates the underlying device parameters of
     special files.  In particular, many operating characteristics of
     character special files (e.g. terminals) may be controlled with ioctl()
     requests.  The argument d must be an open file descriptor.

     The third argument to ioctl is traditionally named char *argp.  Most uses
     of ioctl in FreeBSD 3.0 however, require the third argument to be a
     caddr_t or an int.

     An  ioctl request has encoded in it whether the argument is an ``in''
     parameter or ``out'' parameter, and the size of the argument argp in
     bytes.  Macros and defines used in specifying an ioctl request are
     located in the file <sys/ioctl.h>.

IMPLEMENTATION NOTES
     In the non-threaded library ioctl() is implemented as the ioctl syscall.

     In the threaded library, the ioctl syscall is assembled to
     _thread_sys_ioctl() and ioctl() is implemented as a function which locks
     d for read and write, then calls _thread_sys_ioctl().  Before returning,
     ioctl() unlocks d.

RETURN VALUES
     If an error has occurred, a value of -1 is returned and errno is set to
     indicate the error.

ERRORS
     ioctl() will fail if:

     [EBADF]            d is not a valid descriptor.

     [ENOTTY]           d is not associated with a character special device.

     [ENOTTY]           The specified request does not apply to the kind of
                        object that the descriptor d references.

     [EINVAL]           request or argp is not valid.

     [EFAULT]           argp points outside the process's allocated address
                        space.

SEE ALSO
     execve(2), fcntl(2), intro(4), tty(4)

HISTORY
     An ioctl() function call appeared in Version 7 AT&T UNIX.

FreeBSD 11.0-PRERELEASE        December 11, 1993       FreeBSD 11.0-PRERELEASE

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | IMPLEMENTATION NOTES | RETURN VALUES | ERRORS | SEE ALSO | HISTORY

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