1ioctl(2) System Calls ioctl(2)
2
6 ioctl - control device
7
9 #include <unistd.h>
10 #include <stropts.h>
11 int ioctl(int fildes, int request, /* arg */ ...);
13
16 The ioctl() function performs a variety of control functions on devices
17 and streams. For non-streams files, the functions performed by this
18 call are device-specific control functions. The request argument and
19 an optional third argument with varying type are passed to the file
20 designated by fildes and are interpreted by the device driver.
21 For streams files, specific functions are performed by the ioctl()
24 function as described in streamio(7I).
25 The fildes argument is an open file descriptor that refers to a device.
28 The request argument selects the control function to be performed and
29 depends on the device being addressed. The arg argument represents a
30 third argument that has additional information that is needed by this
31 specific device to perform the requested function. The data type of arg
32 depends upon the particular control request, but it is either an int or
33 a pointer to a device-specific data structure.
34 In addition to device-specific and streams functions, generic functions
37 are provided by more than one device driver (for example, the general
38 terminal interface.) See termio(7I)).
39
41 Upon successful completion, the value returned depends upon the device
42 control function, but must be a non-negative integer. Otherwise, −1 is
43 returned and errno is set to indicate the error.
44
46 The ioctl() function will fail for any type of file if:
47 EBADF The fildes argument is not a valid open file descriptor.
49 EINTR A signal was caught during the execution of the ioctl() func‐
52 tion.
53 EINVAL The stream or multiplexer referenced by fildes is linked
56 (directly or indirectly) downstream from a multiplexer.
57 The ioctl() function will also fail if the device driver detects an
61 error. In this case, the error is passed through ioctl() without
62 change to the caller. A particular driver might not have all of the
63 following error cases. Under the following conditions, requests to
64 device drivers may fail and set errno to indicate the error
65 EFAULT The request argument requires a data transfer to or from a
67 buffer pointed to by arg, but arg points to an illegal
68 address.
69 EINVAL The request or arg argument is not valid for this device.
72 EIO Some physical I/O error has occurred.
75 ENOLINK The fildes argument is on a remote machine and the link to
78 that machine is no longer active.
79 ENOTTY The fildes argument is not associated with a streams device
82 that accepts control functions.
83 ENXIO The request and arg arguments are valid for this device
86 driver, but the service requested can not be performed on
87 this particular subdevice.
88 ENODEV The fildes argument refers to a valid streams device, but
91 the corresponding device driver does not support the ioctl()
92 function.
93 Streams errors are described in streamio(7I).
97
99 See attributes(5) for descriptions of the following attributes:
100 ┌─────────────────────────────┬─────────────────────────────┐
105 │ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
106 ├─────────────────────────────┼─────────────────────────────┤
107 │Interface Stability │Standard │
108 └─────────────────────────────┴─────────────────────────────┘
109
111 attributes(5), standards(5), streamio(7I), termio(7I)
112SunOS 5.11 15 Feb 1996 ioctl(2)