tcdrain - wait for transmission of output
int tcdrain(int fildes);
The tcdrain() function shall block until all output written to the object referred to by fildes is transmitted. The fildes argument is an open file descriptor associated with a terminal.
Any attempts to use tcdrain() from a process which is a member of a background process group on a fildes associated with its controlling terminal, shall cause the process group to be sent a SIGTTOU signal. If the calling process is blocking or ignoring SIGTTOU signals, the process shall be allowed to perform the operation, and no signal is sent.
Upon successful completion, 0 shall be returned. Otherwise, -1 shall be returned and errno set to indicate the error.
The tcdrain() function shall fail if:
- The fildes argument is not a valid file descriptor.
- A signal interrupted tcdrain().
- The file associated with fildes is not a terminal.
The tcdrain() function may fail if:
- The process group of the writing process is orphaned, and the writing process is not ignoring or blocking SIGTTOU.
tcflush(), the Base Definitions volume of IEEE Std 1003.1-2001, Chapter 11, General Terminal Interface, <termios.h>, <unistd.h>
First released in Issue 3. Included for alignment with the POSIX.1-1988 standard.
The following new requirements on POSIX implementations derive from alignment with the Single UNIX Specification:
In the DESCRIPTION, the final paragraph is no longer conditional on _POSIX_JOB_CONTROL. This is a FIPS requirement.
The [EIO] error is added.