gen/tcsendbreak.3

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  32 .\"     @(#)tcsendbreak.3       8.1 (Berkeley) 6/4/93
  33 .\" $FreeBSD: src/lib/libc/gen/tcsendbreak.3,v 1.8 2001/10/01 16:08:51 ru Exp $
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  35 .Dd June 4, 1993
  36 .Dt TCSENDBREAK 3
  37 .Os
  38 .Sh NAME
  39 .Nm tcsendbreak ,
  40 .Nm tcdrain ,
  41 .Nm tcflush ,
  42 .Nm tcflow
  43 .Nd line control functions
  44 .Sh LIBRARY
  45 .Lb libc
  46 .Sh SYNOPSIS
  47 .In termios.h
  48 .Ft int
  49 .Fn tcdrain "int fd"
  50 .Ft int
  51 .Fn tcflow "int fd" "int action"
  52 .Ft int
  53 .Fn tcflush "int fd" "int action"
  54 .Ft int
  55 .Fn tcsendbreak "int fd" "int len"
  56 .Sh DESCRIPTION
  57 The
  58 .Fn tcdrain
  59 function waits until all output written to the terminal referenced by
  60 .Fa fd
  61 has been transmitted to the terminal.
  62 .Pp
  63 The
  64 .Fn tcflow
  65 function suspends transmission of data to or the reception of data from
  66 the terminal referenced by
  67 .Fa fd
  68 depending on the value of
  69 .Fa action .
  70 The value of
  71 .Fa action
  72 must be one of the following:
  73 .Bl -tag -width "TCIOFF"
  74 .It Fa TCOOFF
  75 Suspend output.
  76 .It Fa TCOON
  77 Restart suspended output.
  78 .It Fa TCIOFF
  79 Transmit a STOP character, which is intended to cause the terminal to stop
  80 transmitting data to the system.
  81 (See the description of IXOFF in the
  82 .Ql Input Modes
  83 section of
  84 .Xr termios 4 ) .
  85 .It Fa TCION
  86 Transmit a START character, which is intended to cause the terminal to start
  87 transmitting data to the system.
  88 (See the description of IXOFF in the
  89 .Ql Input Modes
  90 section of
  91 .Xr termios 4 ) .
  92 .El
  93 .Pp
  94 The
  95 .Fn tcflush
  96 function discards any data written to the terminal referenced by
  97 .Fa fd
  98 which has not been transmitted to the terminal, or any data received
  99 from the terminal but not yet read, depending on the value of
 100 .Fa action .
 101 The value of
 102 .Fa action
 103 must be one of the following:
 104 .Bl -tag -width "TCIOFLUSH"
 105 .It Fa TCIFLUSH
 106 Flush data received but not read.
 107 .It Fa TCOFLUSH
 108 Flush data written but not transmitted.
 109 .It Fa TCIOFLUSH
 110 Flush both data received but not read and data written but not transmitted.
 111 .El
 112 .Pp
 113 The
 114 .Fn tcsendbreak
 115 function transmits a continuous stream of zero-valued bits for four-tenths
 116 of a second to the terminal referenced by
 117 .Fa fd .
 118 The
 119 .Fa len
 120 parameter is ignored in this implementation.
 121 .Sh RETURN VALUES
 122 Upon successful completion, all of these functions return a value of zero.
 123 .Sh ERRORS
 124 If any error occurs, a value of -1 is returned and the global variable
 125 .Va errno
 126 is set to indicate the error, as follows:
 127 .Bl -tag -width Er
 128 .It Bq Er EBADF
 129 The
 130 .Fa fd
 131 argument is not a valid file descriptor.
 132 .It Bq Er EINVAL
 133 The
 134 .Fa action
 135 argument is not a proper value.
 136 .It Bq Er ENOTTY
 137 The file associated with
 138 .Fa fd
 139 is not a terminal.
 140 .It Bq Er EINTR
 141 A signal interrupted the
 142 .Fn tcdrain
 143 function.
 144 .El
 145 .Sh SEE ALSO
 146 .Xr tcsetattr 3 ,
 147 .Xr termios 4
 148 .Sh STANDARDS
 149 The
 150 .Fn tcsendbreak ,
 151 .Fn tcdrain ,
 152 .Fn tcflush
 153 and
 154 .Fn tcflow
 155 functions are expected to be compliant with the
 156 .St -p1003.1-88
 157 specification.