PROLOG

       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of
       this interface may differ (consult the corresponding Linux  manual  page  for  details  of
       Linux behavior), or the interface may not be implemented on Linux.

NAME

       tcdrain — wait for transmission of output

SYNOPSIS

       #include <termios.h>

       int tcdrain(int fildes);

DESCRIPTION

       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 thread is blocking SIGTTOU signals or the
       process is ignoring  SIGTTOU  signals,  the  process  shall  be  allowed  to  perform  the
       operation, and no signal is sent.

RETURN VALUE

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

ERRORS

       The tcdrain() function shall fail if:

       EBADF  The fildes argument is not a valid file descriptor.

       EINTR  A signal interrupted tcdrain().

       EIO    The process group of the writing process is orphaned, the  calling  thread  is  not
              blocking SIGTTOU, and the process is not ignoring SIGTTOU.

       ENOTTY The file associated with fildes is not a terminal.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       None.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       tcflush()

       The  Base  Definitions  volume  of  POSIX.1‐2008,  Chapter 11, General Terminal Interface,
       <termios.h>

COPYRIGHT

       Portions of this text are reprinted and  reproduced  in  electronic  form  from  IEEE  Std
       1003.1,  2013  Edition,  Standard  for Information Technology -- Portable Operating System
       Interface (POSIX), The Open Group Base Specifications Issue 7, Copyright (C) 2013  by  the
       Institute  of  Electrical  and  Electronics  Engineers,  Inc and The Open Group.  (This is
       POSIX.1-2008 with the  2013  Technical  Corrigendum  1  applied.)  In  the  event  of  any
       discrepancy  between  this  version and the original IEEE and The Open Group Standard, the
       original IEEE and The Open Group Standard is the referee document. The  original  Standard
       can be obtained online at http://www.unix.org/online.html .

       Any  typographical  or  formatting errors that appear in this page are most likely to have
       been introduced during the conversion of the source files to man page  format.  To  report
       such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .