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All Rights Reserved. .\" .TH TCSETATTR 3C "Aug 14, 2002" .SH NAME tcsetattr \- set the parameters associated with the terminal .SH SYNOPSIS .LP .nf #include \fBint\fR \fBtcsetattr\fR(\fBint\fR \fIfildes\fR, \fBint\fR \fIoptional_actions\fR, \fBconst struct termios *\fR\fItermios_p\fR); .fi .SH DESCRIPTION .sp .LP The \fBtcsetattr()\fR function sets the parameters associated with the terminal referred to by the open file descriptor \fIfildes\fR (an open file descriptor associated with a terminal) from the \fBtermios\fR structure (see \fBtermio\fR(4I)) referenced by \fItermios_p\fR as follows: .RS +4 .TP .ie t \(bu .el o If \fIoptional_actions\fR is \fBTCSANOW\fR, the change will occur immediately. .RE .RS +4 .TP .ie t \(bu .el o If \fIoptional_actions\fR is \fBTCSADRAIN\fR, the change will occur after all output written to \fIfildes\fR is transmitted. This function should be used when changing parameters that affect output. .RE .RS +4 .TP .ie t \(bu .el o If \fIoptional_actions\fR is \fBTCSAFLUSH\fR, the change will occur after all output written to \fIfildes\fR is transmitted, and all input so far received but not read will be discarded before the change is made. .RE .sp .LP If the output baud rate stored in the \fBtermios\fR structure pointed to by \fItermios_p\fR is the zero baud rate, B0, the modem control lines will no longer be asserted. Normally, this will disconnect the line. .sp .LP If the input baud rate stored in the \fBtermios\fR structure pointed to by \fItermios_p\fR is 0, the input baud rate given to the hardware will be the same as the output baud rate stored in the \fBtermios\fR structure. .sp .LP The \fBtcsetattr()\fR function will return successfully if it was able to perform any of the requested actions, even if some of the requested actions could not be performed. It will set all the attributes that implementation supports as requested and leave all the attributes not supported by the implementation unchanged. If no part of the request can be honoured, it will return \fB\(mi1\fR and set \fBerrno\fR to \fBEINVAL\fR. If the input and output baud rates differ and are a combination that is not supported, neither baud rate is changed. A subsequent call to \fBtcgetattr\fR(3C) will return the actual state of the terminal device (reflecting both the changes made and not made in the previous \fBtcsetattr()\fR call). The \fBtcsetattr()\fR function will not change the values in the \fBtermios\fR structure whether or not it actually accepts them. .sp .LP The effect of \fBtcsetattr()\fR is undefined if the value of the \fBtermios\fR structure pointed to by \fItermios_p\fR was not derived from the result of a call to \fBtcgetattr\fR(3C) on \fIfildes\fR; an application should modify only fields and flags defined by this document between the call to \fBtcgetattr\fR(3C) and \fBtcsetattr()\fR, leaving all other fields and flags unmodified. .sp .LP No actions defined by this document, other than a call to \fBtcsetattr()\fR or a close of the last file descriptor in the system associated with this terminal device, will cause any of the terminal attributes defined by this document to change. .sp .LP Attempts to use \fBtcsetattr()\fR from a process which is a member of a background process group on a \fIfildes\fR associated with its controlling terminal, will cause the process group to be sent a \fBSIGTTOU\fR signal. If the calling process is blocking or ignoring \fBSIGTTOU\fR signals, the process is allowed to perform the operation, and no signal is sent. .SH USAGE .sp .LP If trying to change baud rates, applications should call \fBtcsetattr()\fR then call \fBtcgetattr\fR(3C) in order to determine what baud rates were actually selected. .SH RETURN VALUES .sp .LP Upon successful completion, \fB0\fR is returned. Otherwise, \fB\(mi1\fR is returned and \fBerrno\fR is set to indicate the error. .SH ERRORS .sp .LP The \fBtcsetattr()\fR function will fail if: .sp .ne 2 .na \fB\fBEBADF\fR\fR .ad .RS 10n The \fIfildes\fR argument is not a valid file descriptor. .RE .sp .ne 2 .na \fB\fBEINTR\fR\fR .ad .RS 10n A signal interrupted \fBtcsettattr()\fR. .RE .sp .ne 2 .na \fB\fBEINVAL\fR\fR .ad .RS 10n The \fIoptional_actions\fR argument is not a supported value, or an attempt was made to change an attribute represented in the \fBtermios\fR structure to an unsupported value. .RE .sp .ne 2 .na \fB\fBENOTTY\fR\fR .ad .RS 10n The file associated with \fIfildes\fR is not a terminal. .RE .sp .LP The \fBtcsetattr()\fR function may fail if: .sp .ne 2 .na \fB\fBEIO\fR\fR .ad .RS 7n The process group of the writing process is orphaned, and the writing process is not ignoring or blocking \fBSIGTTOU\fR. .RE .SH ATTRIBUTES .sp .LP See \fBattributes\fR(7) for descriptions of the following attributes: .sp .sp .TS box; c | c l | l . ATTRIBUTE TYPE ATTRIBUTE VALUE _ Interface Stability Standard _ MT-Level MT-Safe, and Async-Signal-Safe .TE .SH SEE ALSO .sp .LP .BR cfgetispeed (3C), .BR tcgetattr (3C), .BR termio (4I), .BR attributes (7), .BR standards (7)