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Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.Dd July 15, 2020 29.Dt TCSETATTR 3 30.Os 31.Sh NAME 32.Nm cfgetispeed , 33.Nm cfsetispeed , 34.Nm cfgetospeed , 35.Nm cfsetospeed , 36.Nm cfsetspeed , 37.Nm cfmakeraw , 38.Nm cfmakesane , 39.Nm tcgetattr , 40.Nm tcsetattr 41.Nd manipulating the termios structure 42.Sh LIBRARY 43.Lb libc 44.Sh SYNOPSIS 45.In termios.h 46.Ft speed_t 47.Fn cfgetispeed "const struct termios *t" 48.Ft int 49.Fn cfsetispeed "struct termios *t" "speed_t speed" 50.Ft speed_t 51.Fn cfgetospeed "const struct termios *t" 52.Ft int 53.Fn cfsetospeed "struct termios *t" "speed_t speed" 54.Ft int 55.Fn cfsetspeed "struct termios *t" "speed_t speed" 56.Ft void 57.Fn cfmakeraw "struct termios *t" 58.Ft void 59.Fn cfmakesane "struct termios *t" 60.Ft int 61.Fn tcgetattr "int fd" "struct termios *t" 62.Ft int 63.Fn tcsetattr "int fd" "int action" "const struct termios *t" 64.Sh DESCRIPTION 65The 66.Fn cfmakeraw , 67.Fn cfmakesane , 68.Fn tcgetattr 69and 70.Fn tcsetattr 71functions are provided for getting and setting the termios structure. 72.Pp 73The 74.Fn cfgetispeed , 75.Fn cfsetispeed , 76.Fn cfgetospeed , 77.Fn cfsetospeed 78and 79.Fn cfsetspeed 80functions are provided for getting and setting the baud rate values in 81the termios structure. 82The effects of the functions on the terminal as described below 83do not become effective, nor are all errors detected, until the 84.Fn tcsetattr 85function is called. 86Certain values for baud rates set in the termios structure and passed to 87.Fn tcsetattr 88have special meanings. 89These are discussed in the portion of the manual page that describes the 90.Fn tcsetattr 91function. 92.Sh GETTING AND SETTING THE BAUD RATE 93The input and output baud rates are found in the termios structure. 94The unsigned integer 95.Li speed_t 96is typedef'd in the include file 97.In termios.h . 98The value of the integer corresponds directly to the baud rate being 99represented, however, the following symbolic values are defined. 100.Bd -literal 101#define B0 0 102#define B50 50 103#define B75 75 104#define B110 110 105#define B134 134 106#define B150 150 107#define B200 200 108#define B300 300 109#define B600 600 110#define B1200 1200 111#define B1800 1800 112#define B2400 2400 113#define B4800 4800 114#define B9600 9600 115#define B19200 19200 116#define B38400 38400 117#ifndef _POSIX_SOURCE 118#define EXTA 19200 119#define EXTB 38400 120#endif /*_POSIX_SOURCE */ 121.Ed 122.Pp 123The 124.Fn cfgetispeed 125function returns the input baud rate in the termios structure referenced by 126.Fa t . 127.Pp 128The 129.Fn cfsetispeed 130function sets the input baud rate in the termios structure referenced by 131.Fa t 132to 133.Fa speed . 134.Pp 135The 136.Fn cfgetospeed 137function returns the output baud rate in the termios structure referenced by 138.Fa t . 139.Pp 140The 141.Fn cfsetospeed 142function sets the output baud rate in the termios structure referenced by 143.Fa t 144to 145.Fa speed . 146.Pp 147The 148.Fn cfsetspeed 149function sets both the input and output baud rate in the termios structure 150referenced by 151.Fa t 152to 153.Fa speed . 154.Pp 155Upon successful completion, the functions 156.Fn cfsetispeed , 157.Fn cfsetospeed , 158and 159.Fn cfsetspeed 160return a value of 0. 161Otherwise, a value of -1 is returned and the global variable 162.Va errno 163is set to indicate the error. 164.Sh GETTING AND SETTING THE TERMIOS STATE 165This section describes the functions that are used to control the general 166terminal interface. 167Unless otherwise noted for a specific command, these functions are restricted 168from use by background processes. 169Attempts to perform these operations shall cause the process group to be sent 170a SIGTTOU signal. 171If the calling process is blocking or ignoring SIGTTOU signals, the process 172is allowed to perform the operation and the SIGTTOU signal is not sent. 173.Pp 174In all the functions, although 175.Fa fd 176is an open file descriptor, the functions affect the underlying terminal 177file, not just the open file description associated with the particular 178file descriptor. 179.Pp 180The 181.Fn cfmakeraw 182function sets the flags stored in the termios structure to a state disabling 183all input and output processing, giving a 184.Dq raw I/O path , 185while the 186.Fn cfmakesane 187function sets them to a state similar to those of a newly created 188terminal device. 189It should be noted that there is no function to reverse this effect. 190This is because there are a variety of processing options that could be 191re-enabled and the correct method is for an application to snapshot the 192current terminal state using the function 193.Fn tcgetattr , 194setting raw or sane mode with 195.Fn cfmakeraw 196or 197.Fn cfmakesane 198and the subsequent 199.Fn tcsetattr , 200and then using another 201.Fn tcsetattr 202with the saved state to revert to the previous terminal state. 203.Pp 204The 205.Fn tcgetattr 206function copies the parameters associated with the terminal referenced 207by 208.Fa fd 209in the termios structure referenced by 210.Fa t . 211This function is allowed from a background process, however, the terminal 212attributes may be subsequently changed by a foreground process. 213.Pp 214The 215.Fn tcsetattr 216function sets the parameters associated with the terminal from the 217termios structure referenced by 218.Fa t . 219The 220.Fa action 221argument is one of 222the following values, as specified in the include file 223.In termios.h . 224.Bl -tag -width "TCSADRAIN" 225.It Fa TCSANOW 226The change occurs immediately. 227.It Fa TCSADRAIN 228The change occurs after all output written to 229.Fa fd 230has been transmitted to the terminal. 231This value of 232.Fa action 233should be used when changing parameters that affect output. 234.It Fa TCSAFLUSH 235The change occurs after all output written to 236.Fa fd 237has been transmitted to the terminal. 238Additionally, any input that has been received but not read is discarded. 239.El 240.Pp 241The 242.Fa action 243may be modified by 244.Em or Ns 'ing 245in 246.Fa TCSASOFT 247which causes the values of the 248.Va c_cflag , 249.Va c_ispeed , 250and 251.Va c_ospeed 252fields to be ignored. 253.Pp 254The 0 baud rate is used to terminate the connection. 255If 0 is specified as the output speed to the function 256.Fn tcsetattr , 257modem control will no longer be asserted on the terminal, disconnecting 258the terminal. 259.Pp 260If zero is specified as the input speed to the function 261.Fn tcsetattr , 262the input baud rate will be set to the same value as that specified by 263the output baud rate. 264.Pp 265If 266.Fn tcsetattr 267is unable to make any of the requested changes, it returns -1 and 268sets errno. 269Otherwise, it makes all of the requested changes it can. 270If the specified input and output baud rates differ and are a combination 271that is not supported, neither baud rate is changed. 272.Pp 273Upon successful completion, the functions 274.Fn tcgetattr 275and 276.Fn tcsetattr 277return a value of 0. 278Otherwise, they 279return -1 and the global variable 280.Va errno 281is set to indicate the error, as follows: 282.Bl -tag -width Er 283.It Bq Er EBADF 284The 285.Fa fd 286argument to 287.Fn tcgetattr 288or 289.Fn tcsetattr 290was not a valid file descriptor. 291.It Bq Er EINTR 292The 293.Fn tcsetattr 294function was interrupted by a signal. 295.It Bq Er EINVAL 296The 297.Fa action 298argument to the 299.Fn tcsetattr 300function was not valid, or an attempt was made to change an attribute 301represented in the termios structure to an unsupported value. 302.It Bq Er ENOTTY 303The file associated with the 304.Fa fd 305argument to 306.Fn tcgetattr 307or 308.Fn tcsetattr 309is not a terminal. 310.El 311.Sh SEE ALSO 312.Xr tcsendbreak 3 , 313.Xr termios 4 314.Sh STANDARDS 315The 316.Fn cfgetispeed , 317.Fn cfsetispeed , 318.Fn cfgetospeed , 319.Fn cfsetospeed , 320.Fn tcgetattr 321and 322.Fn tcsetattr 323functions are expected to be compliant with the 324.St -p1003.1-88 325specification. 326The 327.Fn cfmakeraw , 328.Fn cfmakesane 329and 330.Fn cfsetspeed 331functions, 332as well as the 333.Li TCSASOFT 334option to the 335.Fn tcsetattr 336function are extensions to the 337.St -p1003.1-88 338specification. 339