tcsetattrfd

tcsetattrfd is a non-POSIX extension of the terminal attribute interface. It mirrors the general purpose idea of tcsetattr but is implemented as an auxiliary function on some systems to operate on a file descriptor that is tied to a controlling terminal. Because it is not part of the POSIX standard, its availability and exact semantics vary by platform and library implementation.

Prototype and semantics

The typical prototype is similar to the standard tcsetattr:

int tcsetattrfd(int fd, int optional_actions, const struct termios *termios_p);

- fd: a file descriptor associated with a terminal for which the attributes will be set.

- optional_actions: one of the same values used by tcsetattr (for example, TCSANOW, TCSADRAIN, TCSAFLUSH) determining when changes take effect.

- termios_p: a pointer to a termios structure containing the desired terminal attributes.

Return value and errors

On success, tcsetattrfd returns 0. On error, -1 is returned and errno is set to indicate the error (for example EBADF, ENOTTY, EINVAL, or EIO, among others). The exact set of possible errors may be implementation-dependent.

Usage and portability

Because tcsetattrfd is not part of the standard C or POSIX APIs, code that uses it is not portable across all Unix-like systems. Programs that require portability typically use tcgetattr/tcsetattr with a terminal file descriptor obtained from open /dev/tty or a controlling terminal. tcsetattrfd may be used in environments where the extension is documented and supported, often to address specific use cases involving terminal-like behavior on file descriptors that are not direct terminal devices.

See also

tcgetattr, tcsetattr, termios, TCSANOW, TCSADRAIN, TCSAFLUSH.