Quick Answer: Why Ioctl Is Used In Linux?

What is inappropriate ioctl for device?

“inappropriate ioctl for device” is the error string for the ENOTTY error.

More generally, it is triggered when doing an ioctl on a device that does not support that ioctl, hence the error string.

To find out what ioctl is being made that fails, and on what file descriptor, run the script under strace/truss..

How do you pronounce ioctl?

Like the Linux ioctl. Pronounced “i-oct-el”.

What is Unix file descriptor?

In Unix and related computer operating systems, a file descriptor (FD, less frequently fildes) is an abstract indicator (handle) used to access a file or other input/output resource, such as a pipe or network socket. File descriptors form part of the POSIX application programming interface.

What is ioctl Linux?

The ioctl() system call manipulates the underlying device parameters of special files. … 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

How is ioctl implemented in Linux?

ioctl() is typically implemented as part of the corresponding driver, and then an appropriate function pointer is initialised with it, exactly as in other system calls like open() , read() , etc. For example, in character drivers, it is the ioctl or unlocked_ioctl (since kernel 2.6.

What does ioctl stand for?

input/output controlIn computing, ioctl (an abbreviation of input/output control) is a system call for device-specific input/output operations and other operations which cannot be expressed by regular system calls. It takes a parameter specifying a request code; the effect of a call depends completely on the request code.

Is ioctl blocking call?

In addition to SELECT, applications can use the IOCTL or FCNTL calls to help perform asynchronous (nonblocking) socket operations. The IOCTL call has many functions; establishing blocking mode is only one of its functions. The value in COMMAND determines which function IOCTL will perform.

Is ioctl thread safe?

ioctl() is not one of them, so it IS thread-safe. However, ioctl() is a cancellation point, so the thread can be terminated once it reaches ioctl().