4.3BSD-UWisc/man/cat2/ioctl.2

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IOCTL(2)            UNIX Programmer's Manual             IOCTL(2)



NAME
     ioctl - control device

SYNOPSIS
     #include <sys/ioctl.h>

     ioctl(d, request, argp)
     int d;
     unsigned long request;
     char *argp;

DESCRIPTION
     _I_o_c_t_l performs a variety of functions on open descriptors.
     In particular, many operating characteristics of character
     special files (e.g. terminals) may be controlled with _i_o_c_t_l
     requests.  The writeups of various devices in section 4 dis-
     cuss how _i_o_c_t_l applies to them.

     An  ioctl _r_e_q_u_e_s_t has encoded in it whether the argument is
     an "in" parameter or "out" parameter, and the size of the
     argument _a_r_g_p in bytes.  Macros and defines used in specify-
     ing an ioctl _r_e_q_u_e_s_t are located in the file <_s_y_s/_i_o_c_t_l._h>.

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

ERRORS
     _I_o_c_t_l will fail if one or more of the following are true:

     [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 refer-
                    ences.

     [EINVAL]       _R_e_q_u_e_s_t or _a_r_g_p is not valid.

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












Printed 12/27/86          March 4, 1986                         1