TCSAFLUSH

TCSAFLUSH is a constant defined in termios.h and used as the optional_actions parameter to the POSIX tcsetattr function. It indicates that the change to the terminal attributes should occur after flushing both the input and the output queues. The name derives from the idea of flushing (discarding) pending data before applying the new settings.

When tcsetattr is called with TCSAFLUSH, any data still in the input queue and any data waiting to be written to the output queue is discarded before the terminal attributes are updated. This is in contrast to TCSANOW, which applies changes immediately, and TCSADRAIN, which applies changes after all output has been transmitted.

Typical usage involves including termios.h and calling tcsetattr with the desired file descriptor of a terminal device, the TCSAFLUSH option, and a pointer to a configured termios structure. It is commonly used when reconfiguring a terminal in a program that needs to ensure that stale or partial input does not affect the new settings.

Compatibility: TCSAFLUSH is defined by POSIX. It is supported on most UNIX-like systems, including Linux and BSD-derived platforms. Availability on other platforms may vary, and not all environments support flushing behavior.

See also: TCSANOW, TCSADRAIN, termios, tcsetattr.