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@(#)tcsetattr.3 8.3 (Berkeley) 1/2/94
$FreeBSD: src/lib/libc/gen/tcsetattr.3,v 1.9 2001/10/01 16:08:51 ru Exp $
.Dd January 2, 1994 .Dt TCSETATTR 3 .Os .Sh NAME .Nm cfgetispeed , .Nm cfgetospeed , .Nm cfmakeraw , .Nm cfsetispeed , .Nm cfsetospeed , .Nm cfsetspeed , .Nm tcgetattr , .Nm tcsetattr .Nd manipulating the termios structure .Sh LIBRARY .Lb libc .Sh SYNOPSIS n termios.h .Ft speed_t .Fo cfgetispeed .Fa "const struct termios *termios_p" .Fc .Ft speed_t .Fo cfgetospeed .Fa "const struct termios *termios_p" .Fc .Ft void .Fo cfmakeraw .Fa "struct termios *termios_p" .Fc .Ft int .Fo cfsetispeed .Fa "struct termios *termios_p" .Fa "speed_t speed" .Fc .Ft int .Fo cfsetospeed .Fa "struct termios *termios_p" .Fa "speed_t speed" .Fc .Ft int .Fo cfsetspeed .Fa "struct termios *termios_p" .Fa "speed_t speed" .Fc .Ft int .Fo tcgetattr .Fa "int fildes" .Fa "struct termios *termios_p" .Fc .Ft int .Fo tcsetattr .Fa "int fildes" .Fa "int optional_actions" .Fa "const struct termios *termios_p" .Fc .Sh DESCRIPTION The .Fn cfmakeraw , .Fn tcgetattr , and .Fn tcsetattr functions are provided for getting and setting the termios structure.
p The .Fn cfgetispeed , .Fn cfsetispeed , .Fn cfgetospeed , .Fn cfsetospeed , and .Fn cfsetspeed functions are provided for getting and setting the baud rate values in the termios structure. As described below, the effects of the functions on the terminal do not become effective, nor are all errors detected, until the .Fn tcsetattr function is called. Certain values for baud rates, set in the termios structure and passed to .Fn tcsetattr , have special meanings. These are discussed in the portion of the manual page that describes the .Fn tcsetattr function. .Sh GETTING AND SETTING THE BAUD RATE The input and output baud rates are found in the termios structure. The unsigned integer .Li speed_t is typedef'd in the include file .Aq Pa termios.h . The value of the integer corresponds directly to the baud rate being represented; however, the following symbolic values are defined: d -literal #define B0 0 #define B50 50 #define B75 75 #define B110 110 #define B134 134 #define B150 150 #define B200 200 #define B300 300 #define B600 600 #define B1200 1200 #define B1800 1800 #define B2400 2400 #define B4800 4800 #define B9600 9600 #define B19200 19200 #define B38400 38400 #ifndef _POSIX_C_SOURCE #define EXTA 19200 #define EXTB 38400 #endif /*_POSIX_C_SOURCE */ .Ed
p The .Fn cfgetispeed function returns the input baud rate in the termios structure referenced by .Fa termios_p .
p The .Fn cfsetispeed function sets the input baud rate in the termios structure referenced by .Fa termios_p to .Fa speed .
p The .Fn cfgetospeed function returns the output baud rate in the termios structure referenced by .Fa termios_p .
p The .Fn cfsetospeed function sets the output baud rate in the termios structure referenced by .Fa termios_p to .Fa speed .
p The .Fn cfsetspeed function sets both the input and output baud rate in the termios structure referenced by .Fa termios_p to .Fa speed .
p Upon successful completion, the functions .Fn cfsetispeed , .Fn cfsetospeed , and .Fn cfsetspeed return a value of 0. Otherwise, a value of -1 is returned and the global variable .Va errno is set to indicate the error. .Sh GETTING AND SETTING THE TERMIOS STATE This section describes the functions that are used to control the general terminal interface. Unless otherwise noted for a specific command, these functions are restricted from use by background processes. Attempts to perform these operations shall 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 the SIGTTOU signal is not sent.
p In all of the functions, although .Fa fildes is an open file descriptor, the functions affect the underlying terminal file, not just the open file description that is associated with the particular file descriptor.
p The .Fn cfmakeraw function sets the flags stored in the termios structure to a state disabling all input and output processing, giving a .Dq raw I/O path . It should be noted that there is no function to reverse this effect. Because a variety of processing options could be re-enabled, the correct method is for an application to snapshot the current terminal state using the function .Fn tcgetattr , setting raw mode with .Fn cfmakeraw and the subsequent .Fn tcsetattr , and then using another .Fn tcsetattr with the saved state to revert to the previous terminal state.
p The .Fn tcgetattr function copies the parameters associated with the terminal referenced by .Fa fildes in the termios structure referenced by .Fa termios_p . This function is allowed from a background process; however, the terminal attributes may be subsequently changed by a foreground process.
p The .Fn tcsetattr function sets the parameters associated with the terminal from the termios structure referenced by .Fa termios_p . The .Fa optional_actions field is created by .Em or Ns 'ing the following values, as specified in the include file .Aq Pa termios.h . l -tag -width "TCSADRAIN" t Fa TCSANOW The change occurs immediately. t Fa TCSADRAIN The change occurs after all output written to .Fa fildes has been transmitted to the terminal. This value of .Fa optional_actions should be used when changing parameters that affect output. t Fa TCSAFLUSH The change occurs after all output written to .Fa fildes has been transmitted to the terminal. Additionally, any input that has been received but not read is discarded. t Fa TCSASOFT If this value is .Em or Ns 'ed into the .Fa optional_actions value, the values of the .Em c_cflag , .Em c_ispeed , and .Em c_ospeed fields are ignored. .El
p The 0 baud rate is used to terminate the connection. If 0 is specified as the output speed to the function .Fn tcsetattr , modem control will no longer be asserted on the terminal, disconnecting the terminal.
p If zero is specified as the input speed to the function .Fn tcsetattr , the input baud rate will be set to the same value as that specified by the output baud rate.
p If .Fn tcsetattr is unable to make any of the requested changes, it returns -1 and sets errno. Otherwise, it makes all of the requested changes it can. If the specified input and output baud rates differ and are a combination that is not supported, neither baud rate is changed.
p Upon successful completion, the functions .Fn tcgetattr and .Fn tcsetattr return a value of 0. Otherwise, they return -1 and the global variable .Va errno is set to indicate the error, as follows: l -tag -width Er t Bq Er EBADF The .Fa fildes argument to .Fn tcgetattr or .Fn tcsetattr was not a valid file descriptor. t Bq Er EINTR The .Fn tcsetattr function was interrupted by a signal. t Bq Er EINVAL The .Fa optional_actions argument to the .Fn tcsetattr function was not valid, or an attempt was made to change an attribute represented in the termios structure to an unsupported value. t Bq Er ENOTTY The file associated with the .Fa fildes argument to .Fn tcgetattr or .Fn tcsetattr is not a terminal. .El .Sh SEE ALSO .Xr tcsendbreak 3 , .Xr termios 4 .Sh STANDARDS The .Fn cfgetispeed , .Fn cfsetispeed , .Fn cfgetospeed , .Fn cfsetospeed , .Fn tcgetattr , and .Fn tcsetattr functions are expected to be compliant with the .St -p1003.1-88 specification. The .Fn cfmakeraw and .Fn cfsetspeed functions, as well as the .Li TCSASOFT option to the .Fn tcsetattr function are extensions to the .St -p1003.1-88 specification.