TCFLOW(3)                  POSIX Programmer's Manual                 TCFLOW(3)



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

NNAAMMEE
       tcflow -- suspend or restart the transmission or reception of data

SSYYNNOOPPSSIISS
       #include <termios.h>

       int tcflow(int _f_i_l_d_e_s, int _a_c_t_i_o_n);

DDEESSCCRRIIPPTTIIOONN
       The _t_c_f_l_o_w() function shall suspend or restart transmission or
       reception of data on the object referred to by _f_i_l_d_e_s, depending on the
       value of _a_c_t_i_o_n.  The _f_i_l_d_e_s argument is an open file descriptor
       associated with a terminal.

        *  If _a_c_t_i_o_n is TCOOFF, output shall be suspended.

        *  If _a_c_t_i_o_n is TCOON, suspended output shall be restarted.

        *  If _a_c_t_i_o_n is TCIOFF and _f_i_l_d_e_s refers to a terminal device, the
           system shall transmit a STOP character, which is intended to cause
           the terminal device to stop transmitting data to the system. If
           _f_i_l_d_e_s is associated with a pseudo-terminal, the STOP character
           need not be transmitted.

        *  If _a_c_t_i_o_n is TCION and _f_i_l_d_e_s refers to a terminal device, the
           system shall transmit a START character, which is intended to cause
           the terminal device to start transmitting data to the system. If
           _f_i_l_d_e_s is associated with a pseudo-terminal, the START character
           need not be transmitted.

       The default on the opening of a terminal file is that neither its input
       nor its output are suspended.

       Attempts to use _t_c_f_l_o_w() from a process which is a member of a
       background process group on a _f_i_l_d_e_s 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.

RREETTUURRNN VVAALLUUEE
       Upon successful completion, 0 shall be returned. Otherwise, -1 shall be
       returned and _e_r_r_n_o set to indicate the error.

EERRRROORRSS
       The _t_c_f_l_o_w() function shall fail if:

       EEBBAADDFF  The _f_i_l_d_e_s argument is not a valid file descriptor.

       EEIINNVVAALL The _a_c_t_i_o_n argument is not a supported value.

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

       EENNOOTTTTYY The file associated with _f_i_l_d_e_s is not a terminal.

       _T_h_e _f_o_l_l_o_w_i_n_g _s_e_c_t_i_o_n_s _a_r_e _i_n_f_o_r_m_a_t_i_v_e_.

EEXXAAMMPPLLEESS
       None.

AAPPPPLLIICCAATTIIOONN UUSSAAGGEE
       None.

RRAATTIIOONNAALLEE
       None.

FFUUTTUURREE DDIIRREECCTTIIOONNSS
       None.

SSEEEE AALLSSOO
       _t_c_s_e_n_d_b_r_e_a_k()

       The Base Definitions volume of POSIX.1-2017, _C_h_a_p_t_e_r _1_1, _G_e_n_e_r_a_l
       _T_e_r_m_i_n_a_l _I_n_t_e_r_f_a_c_e, <<tteerrmmiiooss..hh>>

CCOOPPYYRRIIGGHHTT
       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1-2017, Standard for Information Technology --
       Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the
       Institute of Electrical and Electronics Engineers, Inc and The Open
       Group.  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.opengroup.org/unix/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 .



IEEE/The Open Group                  2017                            TCFLOW(3)
