tcflush - flush non-transmitted output data, non-read input data or both
#include <termios.h>
int tcflush(int fildes, int queue_selector);
Upon successful completion, tcflush() discards data written to the object referred to by fildes (an open file descriptor associated with a terminal) but not transmitted, or data received but not read, depending on the value of queue_selector:
- If queue_selector is TCIFLUSH it flushes data received but not read.
- If queue_selector is TCOFLUSH it flushes data written but not transmitted.
- If queue_selector is TCIOFLUSH it flushes both data received but not read and data written but not transmitted.
Attempts to use tcflush() from a process which is a member of a background process group on a fildes associated with its controlling terminal, will cause the process group to be sent a SIGTTOU signal. If the calling process is blocking or ignoring SIGTTOU signals, the process is allowed to perform the operation, and no signal is sent.
Upon successful completion, 0 is returned. Otherwise, -1 is returned and errno is set to indicate the error.
The tcflush() function will fail if:
- [EBADF]
The fildes argument is not a valid file descriptor.
- [EINVAL]
The queue_selector argument is not a supported value.
- [ENOTTY]
The file associated with fildes is not a terminal.
The tcflow() function may fail if:
- [EIO]
The process group of the writing process is orphaned, and the writing process is not ignoring or blocking SIGTTOU.
None.
None.
In the ISO POSIX-1 standard, the possibility of an [EIO] error occurring is described in XBD specification, Terminal Access Control, but it is not mentioned in the tcflow() interface definition. It has become clear that this omission was unintended, so it is likely that the [EIO] error will be reclassified as a "will fail" in a future issue of the POSIX standard.
tcdrain(), <termios.h>, <unistd.h>, the XBD specification, General Terminal Interface.