| blob | c458933a25d16869e162fd78f6bf5b37f7a104c0 |
1 '\" t
2 .\" Copyright 2002 Walter Harms <walter.harms@informatik.uni-oldenburg.de>
3 .\" and Andries Brouwer <aeb@cwi.nl>.
4 .\"
5 .\" SPDX-License-Identifier: GPL-1.0-or-later
6 .\"
7 .TH ioctl_tty 2 (date) "Linux man-pages (unreleased)"
8 .SH NAME
9 ioctl_tty \- ioctls for terminals and serial lines
10 .SH LIBRARY
11 Standard C library
12 .RI ( libc ", " \-lc )
13 .SH SYNOPSIS
14 .nf
15 .B #include <sys/ioctl.h>
16 .BR "#include <asm/termbits.h>" " /* Definition of " "struct termios" ,
17 .BR " struct termios2" ", and"
18 .BR " Bnnn" ", " BOTHER ", " CBAUD ", " CLOCAL ,
19 .BR " TC*" { FLUSH , ON , OFF "} and other constants */"
20 .P
21 .BI "int ioctl(int " fd ", int " op ", ...);"
22 .fi
23 .SH DESCRIPTION
24 The
25 .BR ioctl (2)
26 call for terminals and serial ports accepts many possible operation arguments.
27 Most require a third argument, of varying type, here called
28 .I argp
29 or
30 .IR arg .
31 .P
32 Use of
33 .BR ioctl ()
34 makes for nonportable programs.
35 Use the POSIX interface described in
36 .BR termios (3)
37 whenever possible.
38 .P
39 Please note that
40 .B struct termios
41 from
42 .I <asm/termbits.h>
43 is different and incompatible with
44 .B struct termios
45 from
46 .IR <termios.h> .
47 These ioctl calls require
48 .B struct termios
49 from
50 .IR <asm/termbits.h> .
51 .SS Get and set terminal attributes
52 .TP
53 .B TCGETS
54 Argument:
55 .BI "struct termios\~*" argp
56 .IP
57 Equivalent to
58 .IR "tcgetattr(fd, argp)" .
59 .IP
60 Get the current serial port settings.
61 .TP
62 .B TCSETS
63 Argument:
64 .BI "const struct termios\~*" argp
65 .IP
66 Equivalent to
67 .IR "tcsetattr(fd, TCSANOW, argp)" .
68 .IP
69 Set the current serial port settings.
70 .TP
71 .B TCSETSW
72 Argument:
73 .BI "const struct termios\~*" argp
74 .IP
75 Equivalent to
76 .IR "tcsetattr(fd, TCSADRAIN, argp)" .
77 .IP
78 Allow the output buffer to drain, and
79 set the current serial port settings.
80 .TP
81 .B TCSETSF
82 Argument:
83 .BI "const struct termios\~*" argp
84 .IP
85 Equivalent to
86 .IR "tcsetattr(fd, TCSAFLUSH, argp)" .
87 .IP
88 Allow the output buffer to drain, discard pending input, and
89 set the current serial port settings.
90 .P
91 The following four ioctls, added in Linux 2.6.20,
92 .\" commit 64bb6c5e1ddcd47c951740485026ef08975ee2e6
93 .\" commit 592ee3a5e5e2a981ef2829a0380093006d045661
94 are just like
95 .BR TCGETS ,
96 .BR TCSETS ,
97 .BR TCSETSW ,
98 .BR TCSETSF ,
99 except that they take a
100 .I "struct termios2\~*"
101 instead of a
102 .IR "struct termios\~*" .
103 If the structure member
104 .B c_cflag
105 contains the flag
106 .BR BOTHER ,
107 then the baud rate is stored in the structure members
108 .B c_ispeed
109 and
110 .B c_ospeed
111 as integer values.
112 These ioctls are not supported on all architectures.
113 .RS
114 .TS
115 lb l.
116 TCGETS2 \fBstruct termios2 *\fPargp
117 TCSETS2 \fBconst struct termios2 *\fPargp
118 TCSETSW2 \fBconst struct termios2 *\fPargp
119 TCSETSF2 \fBconst struct termios2 *\fPargp
120 .TE
121 .RE
122 .P
123 The following four ioctls are just like
124 .BR TCGETS ,
125 .BR TCSETS ,
126 .BR TCSETSW ,
127 .BR TCSETSF ,
128 except that they take a
129 .I "struct termio\~*"
130 instead of a
131 .IR "struct termios\~*" .
132 .RS
133 .TS
134 lb l.
135 TCGETA \fBstruct termio *\fPargp
136 TCSETA \fBconst struct termio *\fPargp
137 TCSETAW \fBconst struct termio *\fPargp
138 TCSETAF \fBconst struct termio *\fPargp
139 .TE
140 .RE
141 .SS Locking the termios structure
142 The
143 .I termios
144 structure of a terminal can be locked.
145 The lock is itself a
146 .I termios
147 structure, with nonzero bits or fields indicating a
148 locked value.
149 .TP
150 .B TIOCGLCKTRMIOS
151 Argument:
152 .BI "struct termios\~*" argp
153 .IP
154 Gets the locking status of the
155 .I termios
156 structure of the terminal.
157 .TP
158 .B TIOCSLCKTRMIOS
159 Argument:
160 .BI "const struct termios\~*" argp
161 .IP
162 Sets the locking status of the
163 .I termios
164 structure of the terminal.
165 Only a process with the
166 .B CAP_SYS_ADMIN
167 capability can do this.
168 .SS Get and set window size
169 Window sizes are kept in the kernel, but not used by the kernel
170 (except in the case of virtual consoles, where the kernel will
171 update the window size when the size of the virtual console changes,
172 for example, by loading a new font).
173 .TP
174 .B TIOCGWINSZ
175 Argument:
176 .BI "struct winsize\~*" argp
177 .IP
178 Get window size.
179 .TP
180 .B TIOCSWINSZ
181 Argument:
182 .BI "const struct winsize\~*" argp
183 .IP
184 Set window size.
185 .P
186 The struct used by these ioctls is defined as
187 .P
188 .in +4n
189 .EX
190 struct winsize {
191 unsigned short ws_row;
192 unsigned short ws_col;
193 unsigned short ws_xpixel; /* unused */
194 unsigned short ws_ypixel; /* unused */
195 };
196 .EE
197 .in
198 .P
199 When the window size changes, a
200 .B SIGWINCH
201 signal is sent to the
202 foreground process group.
203 .SS Sending a break
204 .TP
205 .B TCSBRK
206 Argument:
207 .BI "int " arg
208 .IP
209 Equivalent to
210 .IR "tcsendbreak(fd, arg)" .
211 .IP
212 If the terminal is using asynchronous serial data transmission, and
213 .I arg
214 is zero, then send a break (a stream of zero bits) for between
215 0.25 and 0.5 seconds.
216 If the terminal is not using asynchronous
217 serial data transmission, then either a break is sent, or the function
218 returns without doing anything.
219 When
220 .I arg
221 is nonzero, nobody knows what will happen.
222 .IP
223 (SVr4, UnixWare, Solaris, and Linux treat
224 .I "tcsendbreak(fd,arg)"
225 with nonzero
226 .I arg
227 like
228 .IR "tcdrain(fd)" .
229 SunOS treats
230 .I arg
231 as a multiplier, and sends a stream of bits
232 .I arg
233 times as long as done for zero
234 .IR arg .
235 DG/UX and AIX treat
236 .I arg
237 (when nonzero) as a time interval measured in milliseconds.
238 HP-UX ignores
239 .IR arg .)
240 .TP
241 .B TCSBRKP
242 Argument:
243 .BI "int " arg
244 .IP
245 So-called "POSIX version" of
246 .BR TCSBRK .
247 It treats nonzero
248 .I arg
249 as a time interval measured in deciseconds, and does nothing
250 when the driver does not support breaks.
251 .TP
252 .B TIOCSBRK
253 Argument:
254 .B void
255 .IP
256 Turn break on, that is, start sending zero bits.
257 .TP
258 .B TIOCCBRK
259 Argument:
260 .B void
261 .IP
262 Turn break off, that is, stop sending zero bits.
263 .SS Software flow control
264 .TP
265 .B TCXONC
266 Argument:
267 .BI "int " arg
268 .IP
269 Equivalent to
270 .IR "tcflow(fd, arg)" .
271 .IP
272 See
273 .BR tcflow (3)
274 for the argument values
275 .BR TCOOFF ,
276 .BR TCOON ,
277 .BR TCIOFF ,
278 .BR TCION .
279 .SS Buffer count and flushing
280 .TP
281 .B FIONREAD
282 Argument:
283 .BI "int\~*" argp
284 .IP
285 Get the number of bytes in the input buffer.
286 .TP
287 .B TIOCINQ
288 Argument:
289 .BI "int\~*" argp
290 .IP
291 Same as
292 .BR FIONREAD .
293 .TP
294 .B TIOCOUTQ
295 Argument:
296 .BI "int\~*" argp
297 .IP
298 Get the number of bytes in the output buffer.
299 .TP
300 .B TCFLSH
301 Argument:
302 .BI "int " arg
303 .IP
304 Equivalent to
305 .IR "tcflush(fd, arg)" .
306 .IP
307 See
308 .BR tcflush (3)
309 for the argument values
310 .BR TCIFLUSH ,
311 .BR TCOFLUSH ,
312 .BR TCIOFLUSH .
313 .TP
314 .B TIOCSERGETLSR
315 Argument:
316 .BI "int\~*" argp
317 .IP
318 Get line status register.
319 Status register has
320 .B TIOCSER_TEMT
321 bit set when
322 output buffer is empty and also hardware transmitter is physically empty.
323 .IP
324 Does not have to be supported by all serial tty drivers.
325 .IP
326 .BR tcdrain (3)
327 does not wait and returns immediately when
328 .B TIOCSER_TEMT
329 bit is set.
330 .SS Faking input
331 .TP
332 .B TIOCSTI
333 Argument:
334 .BI "const char\~*" argp
335 .IP
336 Insert the given byte in the input queue.
337 .IP
338 Since Linux 6.2,
339 .\" commit 690c8b804ad2eafbd35da5d3c95ad325ca7d5061
340 .\" commit 83efeeeb3d04b22aaed1df99bc70a48fe9d22c4d
341 this operation may require the
342 .B CAP_SYS_ADMIN
343 capability (if the
344 .I dev.tty.legacy_tiocsti
345 sysctl variable is set to false).
346 .SS Redirecting console output
347 .TP
348 .B TIOCCONS
349 Argument:
350 .B void
351 .IP
352 Redirect output that would have gone to
353 .I /dev/console
354 or
355 .I /dev/tty0
356 to the given terminal.
357 If that was a pseudoterminal master, send it to the slave.
358 Before Linux 2.6.10,
359 anybody can do this as long as the output was not redirected yet;
360 since Linux 2.6.10, only a process with the
361 .B CAP_SYS_ADMIN
362 capability may do this.
363 If output was redirected already, then
364 .B EBUSY
365 is returned,
366 but redirection can be stopped by using this ioctl with
367 .I fd
368 pointing at
369 .I /dev/console
370 or
371 .IR /dev/tty0 .
372 .SS Controlling terminal
373 .TP
374 .B TIOCSCTTY
375 Argument:
376 .BI "int " arg
377 .IP
378 Make the given terminal the controlling terminal of the calling process.
379 The calling process must be a session leader and not have a
380 controlling terminal already.
381 For this case,
382 .I arg
383 should be specified as zero.
384 .IP
385 If this terminal is already the controlling terminal
386 of a different session group, then the ioctl fails with
387 .BR EPERM ,
388 unless the caller has the
389 .B CAP_SYS_ADMIN
390 capability and
391 .I arg
392 equals 1, in which case the terminal is stolen, and all processes that had
393 it as controlling terminal lose it.
394 .TP
395 .B TIOCNOTTY
396 Argument:
397 .B void
398 .IP
399 If the given terminal was the controlling terminal of the calling process,
400 give up this controlling terminal.
401 If the process was session leader,
402 then send
403 .B SIGHUP
404 and
405 .B SIGCONT
406 to the foreground process group
407 and all processes in the current session lose their controlling terminal.
408 .SS Process group and session ID
409 .TP
410 .B TIOCGPGRP
411 Argument:
412 .BI "pid_t\~*" argp
413 .IP
414 When successful, equivalent to
415 .IR "*argp = tcgetpgrp(fd)" .
416 .IP
417 Get the process group ID of the foreground process group on this terminal.
418 .TP
419 .B TIOCSPGRP
420 Argument:
421 .BI "const pid_t\~*" argp
422 .IP
423 Equivalent to
424 .IR "tcsetpgrp(fd, *argp)" .
425 .IP
426 Set the foreground process group ID of this terminal.
427 .TP
428 .B TIOCGSID
429 Argument:
430 .BI "pid_t\~*" argp
431 .IP
432 When successful, equivalent to
433 .IR "*argp = tcgetsid(fd)" .
434 .IP
435 Get the session ID of the given terminal.
436 This fails with the error
437 .B ENOTTY
438 if the terminal is not a master pseudoterminal
439 and not our controlling terminal.
440 Strange.
441 .SS Exclusive mode
442 .TP
443 .B TIOCEXCL
444 Argument:
445 .B void
446 .IP
447 Put the terminal into exclusive mode.
448 No further
449 .BR open (2)
450 operations on the terminal are permitted.
451 (They fail with
452 .BR EBUSY ,
453 except for a process with the
454 .B CAP_SYS_ADMIN
455 capability.)
456 .TP
457 .B TIOCGEXCL
458 Argument:
459 .BI "int\~*" argp
460 .IP
461 (since Linux 3.8)
462 If the terminal is currently in exclusive mode,
463 place a nonzero value in the location pointed to by
464 .IR argp ;
465 otherwise, place zero in
466 .IR *argp .
467 .TP
468 .B TIOCNXCL
469 Argument:
470 .B void
471 .IP
472 Disable exclusive mode.
473 .SS Line discipline
474 .TP
475 .B TIOCGETD
476 Argument:
477 .BI "int\~*" argp
478 .IP
479 Get the line discipline of the terminal.
480 .TP
481 .B TIOCSETD
482 Argument:
483 .BI "const int\~*" argp
484 .IP
485 Set the line discipline of the terminal.
486 .SS Pseudoterminal ioctls
487 .TP
488 .B TIOCPKT
489 Argument:
490 .BI "const int\~*" argp
491 .IP
492 Enable (when
493 .RI * argp
494 is nonzero) or disable packet mode.
495 Can be applied to the master side of a pseudoterminal only (and will return
496 .B ENOTTY
497 otherwise).
498 In packet mode, each subsequent
499 .BR read (2)
500 will return a packet that either contains a single nonzero control byte,
501 or has a single byte containing zero (\[aq]\e0\[aq]) followed by data
502 written on the slave side of the pseudoterminal.
503 If the first byte is not
504 .B TIOCPKT_DATA
505 (0), it is an OR of one
506 or more of the following bits:
507 .IP
508 .ad l
509 .TS
510 lb l.
511 TIOCPKT_FLUSHREAD T{
512 The read queue for the terminal is flushed.
513 T}
514 TIOCPKT_FLUSHWRITE T{
515 The write queue for the terminal is flushed.
516 T}
517 TIOCPKT_STOP T{
518 Output to the terminal is stopped.
519 T}
520 TIOCPKT_START T{
521 Output to the terminal is restarted.
522 T}
523 TIOCPKT_DOSTOP T{
524 The start and stop characters are \fB\[ha]S\fP/\fB\[ha]Q\fP.
525 T}
526 TIOCPKT_NOSTOP T{
527 The start and stop characters are not \fB\[ha]S\fP/\fB\[ha]Q\fP.
528 T}
529 .TE
530 .ad
531 .IP
532 While packet mode is in use, the presence
533 of control status information to be read
534 from the master side may be detected by a
535 .BR select (2)
536 for exceptional conditions or a
537 .BR poll (2)
538 for the
539 .B POLLPRI
540 event.
541 .IP
542 This mode is used by
543 .BR rlogin (1)
544 and
545 .BR rlogind (8)
546 to implement a remote-echoed,
547 locally \fB\[ha]S\fP/\fB\[ha]Q\fP flow-controlled remote login.
548 .TP
549 .B TIOCGPKT
550 Argument:
551 .BI "const int\~*" argp
552 .IP
553 (since Linux 3.8)
554 Return the current packet mode setting in the integer pointed to by
555 .IR argp .
556 .TP
557 .B TIOCSPTLCK
558 Argument:
559 .BI "int\~*" argp
560 .IP
561 Set (if
562 .I *argp
563 is nonzero) or remove (if
564 .I *argp
565 is zero) the lock on the pseudoterminal slave device.
566 (See also
567 .BR unlockpt (3).)
568 .TP
569 .B TIOCGPTLCK
570 Argument:
571 .BI "int\~*" argp
572 .IP
573 (since Linux 3.8)
574 Place the current lock state of the pseudoterminal slave device
575 in the location pointed to by
576 .IR argp .
577 .TP
578 .B TIOCGPTPEER
579 Argument:
580 .BI "int " flags
581 .IP
582 .\" commit 54ebbfb1603415d9953c150535850d30609ef077
583 (since Linux 4.13)
584 Given a file descriptor in
585 .I fd
586 that refers to a pseudoterminal master,
587 open (with the given
588 .BR open (2)-style
589 .IR flags )
590 and return a new file descriptor that refers to the peer
591 pseudoterminal slave device.
592 This operation can be performed
593 regardless of whether the pathname of the slave device
594 is accessible through the calling process's mount namespace.
595 .IP
596 Security-conscious programs interacting with namespaces may wish to use this
597 operation rather than
598 .BR open (2)
599 with the pathname returned by
600 .BR ptsname (3),
601 and similar library functions that have insecure APIs.
602 (For example, confusion can occur in some cases using
603 .BR ptsname (3)
604 with a pathname where a devpts filesystem
605 has been mounted in a different mount namespace.)
606 .P
607 The BSD ioctls
608 .BR TIOCSTOP ,
609 .BR TIOCSTART ,
610 .BR TIOCUCNTL ,
611 and
612 .B TIOCREMOTE
613 have not been implemented under Linux.
614 .SS Modem control
615 .TP
616 .B TIOCMGET
617 Argument:
618 .BI "int\~*" argp
619 .IP
620 Get the status of modem bits.
621 .TP
622 .B TIOCMSET
623 Argument:
624 .BI "const int\~*" argp
625 .IP
626 Set the status of modem bits.
627 .TP
628 .B TIOCMBIC
629 Argument:
630 .BI "const int\~*" argp
631 .IP
632 Clear the indicated modem bits.
633 .TP
634 .B TIOCMBIS
635 Argument:
636 .BI "const int\~*" argp
637 .IP
638 Set the indicated modem bits.
639 .P
640 The following bits are used by the above ioctls:
641 .P
642 .TS
643 lb l.
644 TIOCM_LE DSR (data set ready/line enable)
645 TIOCM_DTR DTR (data terminal ready)
646 TIOCM_RTS RTS (request to send)
647 TIOCM_ST Secondary TXD (transmit)
648 TIOCM_SR Secondary RXD (receive)
649 TIOCM_CTS CTS (clear to send)
650 TIOCM_CAR DCD (data carrier detect)
651 TIOCM_CD see TIOCM_CAR
652 TIOCM_RNG RNG (ring)
653 TIOCM_RI see TIOCM_RNG
654 TIOCM_DSR DSR (data set ready)
655 .TE
656 .TP
657 .B TIOCMIWAIT
658 Argument:
659 .BI "int " arg
660 .IP
661 Wait for any of the 4 modem bits (DCD, RI, DSR, CTS) to change.
662 The bits of interest are specified as a bit mask in
663 .IR arg ,
664 by ORing together any of the bit values,
665 .BR TIOCM_RNG ,
666 .BR TIOCM_DSR ,
667 .BR TIOCM_CD ,
668 and
669 .BR TIOCM_CTS .
670 The caller should use
671 .B TIOCGICOUNT
672 to see which bit has changed.
673 .TP
674 .B TIOCGICOUNT
675 Argument:
676 .BI "struct serial_icounter_struct\~*" argp
677 .IP
678 Get counts of input serial line interrupts (DCD, RI, DSR, CTS).
679 The counts are written to the
680 .I serial_icounter_struct
681 structure pointed to by
682 .IR argp .
683 .IP
684 Note: both 1->0 and 0->1 transitions are counted, except for
685 RI, where only 0->1 transitions are counted.
686 .SS Marking a line as local
687 .TP
688 .B TIOCGSOFTCAR
689 Argument:
690 .BI "int\~*" argp
691 .IP
692 ("Get software carrier flag")
693 Get the status of the CLOCAL flag in the c_cflag field of the
694 .I termios
695 structure.
696 .TP
697 .B TIOCSSOFTCAR
698 Argument:
699 .BI "const int\~*" argp
700 .IP
701 ("Set software carrier flag")
702 Set the CLOCAL flag in the
703 .I termios
704 structure when
705 .RI * argp
706 is nonzero, and clear it otherwise.
707 .P
708 If the
709 .B CLOCAL
710 flag for a line is off, the hardware carrier detect (DCD)
711 signal is significant, and an
712 .BR open (2)
713 of the corresponding terminal will block until DCD is asserted,
714 unless the
715 .B O_NONBLOCK
716 flag is given.
717 If
718 .B CLOCAL
719 is set, the line behaves as if DCD is always asserted.
720 The software carrier flag is usually turned on for local devices,
721 and is off for lines with modems.
722 .SS Linux-specific
723 For the
724 .B TIOCLINUX
725 ioctl, see
726 .BR ioctl_console (2).
727 .SS Kernel debugging
728 .B "#include <linux/tty.h>"
729 .TP
730 .B TIOCTTYGSTRUCT
731 Argument:
732 .BI "struct tty_struct\~*" argp
733 .IP
734 Get the
735 .I tty_struct
736 corresponding to
737 .IR fd .
738 This operation was removed in Linux 2.5.67.
739 .\" commit b3506a09d15dc5aee6d4bb88d759b157016e1864
740 .\" Author: Andries E. Brouwer <andries.brouwer@cwi.nl>
741 .\" Date: Tue Apr 1 04:42:46 2003 -0800
742 .\"
743 .\" [PATCH] kill TIOCTTYGSTRUCT
744 .\"
745 .\" Only used for (dubious) debugging purposes, and exposes
746 .\" internal kernel state.
747 .\"
748 .\" .SS Serial info
749 .\" .BR "#include <linux/serial.h>"
750 .\" .P
751 .\" .TP
752 .\" .BI "TIOCGSERIAL struct serial_struct *" argp
753 .\" Get serial info.
754 .\" .TP
755 .\" .BI "TIOCSSERIAL const struct serial_struct *" argp
756 .\" Set serial info.
757 .SH RETURN VALUE
758 The
759 .BR ioctl (2)
760 system call returns 0 on success.
761 On error, it returns \-1 and sets
762 .I errno
763 to indicate the error.
764 .SH ERRORS
765 .TP
766 .B EINVAL
767 Invalid operation parameter.
768 .TP
769 .B ENOIOCTLCMD
770 Unknown operation.
771 .TP
772 .B ENOTTY
773 Inappropriate
774 .IR fd .
775 .TP
776 .B EPERM
777 Insufficient permission.
778 .SH EXAMPLES
779 Check the condition of DTR on the serial port.
780 .P
781 .\" SRC BEGIN (tiocmget.c)
782 .EX
783 #include <fcntl.h>
784 #include <stdio.h>
785 #include <sys/ioctl.h>
786 #include <unistd.h>
787 \&
788 int
789 main(void)
790 {
791 int fd, serial;
792 \&
793 fd = open("/dev/ttyS0", O_RDONLY);
794 ioctl(fd, TIOCMGET, &serial);
795 if (serial & TIOCM_DTR)
796 puts("TIOCM_DTR is set");
797 else
798 puts("TIOCM_DTR is not set");
799 close(fd);
800 }
801 .EE
802 .\" SRC END
803 .P
804 Get or set arbitrary baudrate on the serial port.
805 .P
806 .\" SRC BEGIN (tcgets.c)
807 .EX
808 /* SPDX-License-Identifier: GPL-2.0-or-later */
809 \&
810 #include <asm/termbits.h>
811 #include <fcntl.h>
812 #include <stdio.h>
813 #include <stdlib.h>
814 #include <sys/ioctl.h>
815 #include <unistd.h>
816 \&
817 int
818 main(int argc, char *argv[])
819 {
820 #if !defined BOTHER
821 fprintf(stderr, "BOTHER is unsupported\en");
822 /* Program may fallback to TCGETS/TCSETS with Bnnn constants */
823 exit(EXIT_FAILURE);
824 #else
825 /* Declare tio structure, its type depends on supported ioctl */
826 # if defined TCGETS2
827 struct termios2 tio;
828 # else
829 struct termios tio;
830 # endif
831 int fd, rc;
832 \&
833 if (argc != 2 && argc != 3 && argc != 4) {
834 fprintf(stderr, "Usage: %s device [output [input] ]\en", argv[0]);
835 exit(EXIT_FAILURE);
836 }
837 \&
838 fd = open(argv[1], O_RDWR | O_NONBLOCK | O_NOCTTY);
839 if (fd < 0) {
840 perror("open");
841 exit(EXIT_FAILURE);
842 }
843 \&
844 /* Get the current serial port settings via supported ioctl */
845 # if defined TCGETS2
846 rc = ioctl(fd, TCGETS2, &tio);
847 # else
848 rc = ioctl(fd, TCGETS, &tio);
849 # endif
850 if (rc) {
851 perror("TCGETS");
852 close(fd);
853 exit(EXIT_FAILURE);
854 }
855 \&
856 /* Change baud rate when more arguments were provided */
857 if (argc == 3 || argc == 4) {
858 /* Clear the current output baud rate and fill a new value */
859 tio.c_cflag &= \[ti]CBAUD;
860 tio.c_cflag |= BOTHER;
861 tio.c_ospeed = atoi(argv[2]);
862 \&
863 /* Clear the current input baud rate and fill a new value */
864 tio.c_cflag &= \[ti](CBAUD << IBSHIFT);
865 tio.c_cflag |= BOTHER << IBSHIFT;
866 /* When 4th argument is not provided reuse output baud rate */
867 tio.c_ispeed = (argc == 4) ? atoi(argv[3]) : atoi(argv[2]);
868 \&
869 /* Set new serial port settings via supported ioctl */
870 # if defined TCSETS2
871 rc = ioctl(fd, TCSETS2, &tio);
872 # else
873 rc = ioctl(fd, TCSETS, &tio);
874 # endif
875 if (rc) {
876 perror("TCSETS");
877 close(fd);
878 exit(EXIT_FAILURE);
879 }
880 \&
881 /* And get new values which were really configured */
882 # if defined TCGETS2
883 rc = ioctl(fd, TCGETS2, &tio);
884 # else
885 rc = ioctl(fd, TCGETS, &tio);
886 # endif
887 if (rc) {
888 perror("TCGETS");
889 close(fd);
890 exit(EXIT_FAILURE);
891 }
892 }
893 \&
894 close(fd);
895 \&
896 printf("output baud rate: %u\en", tio.c_ospeed);
897 printf("input baud rate: %u\en", tio.c_ispeed);
898 \&
899 exit(EXIT_SUCCESS);
900 #endif
901 }
902 .EE
903 .\" SRC END
904 .SH SEE ALSO
905 .BR ldattach (8),
906 .BR ioctl (2),
907 .BR ioctl_console (2),
908 .BR termios (3),
909 .BR pty (7)
910 .\"
911 .\" FIONBIO const int *
912 .\" FIONCLEX void
913 .\" FIOCLEX void
914 .\" FIOASYNC const int *
915 .\" from serial.c:
916 .\" TIOCSERCONFIG void
917 .\" TIOCSERGWILD int *
918 .\" TIOCSERSWILD const int *
919 .\" TIOCSERGSTRUCT struct async_struct *
920 .\" TIOCSERGETMULTI struct serial_multiport_struct *
921 .\" TIOCSERSETMULTI const struct serial_multiport_struct *
922 .\" TIOCGSERIAL, TIOCSSERIAL (see above)