tcgetattr

Synopsis

#include <termios.h>

int tcgetattr(int fildes, struct termios *termios_p);

Status

Partially implemented

Conformance

IEEE Std 1003.1-2017

Description

tcgetattr() - get the parameters associated with the terminal

The tcgetattr() function shall get the parameters associated with the terminal referred to by fildes and store them in the termios structure referenced by termios_p. The fildes argument is an open file descriptor associated with a terminal.

The termios_p argument is a pointer to a termios structure.

The tcgetattr() operation is allowed from any process.

If the terminal device supports different input and output baud rates, the baud rates stored in the termios structure returned by tcgetattr() shall reflect the actual baud rates, even if they are equal. If differing baud rates are not supported, the rate returned as the output baud rate shall be the actual baud rate. If the terminal device does not support split baud rates, the input baud rate stored in the termios structure shall be the output rate (as one of the symbolic values).

Return value

Upon successful completion, 0 shall be returned. Otherwise, -1 shall be returned and errno set to indicate the error.

Errors

The tcgetattr() function shall fail if:

• EBADF - The fildes argument is not a valid file descriptor.

• ENOTTY - The file associated with fildes is not a terminal.

• EINVAL - The file associated with fildes is not a terminal, and the server handling it reports unsupported requests with EINVAL (see POSIX deviations).

POSIX deviations

If the file associated with fildes is not a terminal, the error reported by tcgetattr() depends on the server handling the file. The function is implemented on top of ioctl(), and the kernel forwards every request to the server without checking the type of the file. Servers that do not handle terminal requests report them either with ENOTTY (for example files in jffs2) or with EINVAL (for example pipes and files in dummyfs).