tcflow(3C)

NAME

     tcflow - suspend or restart the transmission or reception of
     data

SYNOPSIS

     #include <termios.h>

     int tcflow(int fildes, int action);

DESCRIPTION

     The tcflow() function suspends transmission or reception  of
     data  on  the object referred to by fildes, depending on the
     value of action.   The  fildes  argument  is  an  open  file
     descriptor associated with a terminal.

        o  If action is TCOOFF, output is suspended.

        o  If action is TCOON, suspended output is restarted.

        o  If action is TCIOFF, the system transmits a STOP char-
           acter,  which is intended to cause the terminal device
           to stop transmitting data to the system.

        o  If action is TCION, the system transmits a START char-
           acter,  which is intended to cause the terminal device
           to start transmitting data to the system.

     The default on the opening of a terminal file is  that  nei-
     ther its input nor its output are suspended.

     Attempts to use tcflow() 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.

RETURN VALUES

     Upon successful completion, 0 is returned. Otherwise, -1  is
     returned and errno is set to indicate the error.

ERRORS

     The tcflow() function will fail if:

     EBADF The fildes argument is not a valid file descriptor.

     EINVAL
           The action 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.

ATTRIBUTES

     See attributes(5) for descriptions of the  following  attri-
     butes:

     ______________________________________________________________
    |       ATTRIBUTE TYPE        |        ATTRIBUTE VALUE        |
    |_____________________________|_______________________________|
    | MT-Level                    | MT-Safe, and Async-Signal-Safe|
    |_____________________________|_______________________________|

SEE ALSO

     tcsendbreak(3C), attributes(5), termio(7I)