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1.1 root 1: .de Ul
2: .ie t \\$1\l'|0\(ul'
3: .el \fI\\$1\fP
4: ..
5: .TH TTY 4
6: .UC 4
7: .SH NAME
8: tty \- general terminal interface
9: .SH DESCRIPTION
10: This section describes
11: both a particular special file
12: .B /dev/tty
13: and the terminal drivers used for conversational computing.
14: .LP
15: .B Line disciplines.
16: .PP
17: The system provides different
18: .I "line disciplines"
19: for controlling communications lines.
20: In this version of the system there are three disciplines available:
21: .IP "old" 8
22: The old (standard) terminal driver. This is used when using the
23: standard shell
24: .IR sh (1)
25: and for compatibility with other standard version 7 UNIX systems.
26: .IP "new"
27: A newer terminal driver, with features for job control; this must
28: be used when using
29: .IR csh (1).
30: See
31: .IR newtty (1)
32: for a short user-level summary.
33: .IP "net"
34: A line discipline used for networking and loading data into
35: the system over communications lines. It allows high speed input
36: at very low overhead, and is described in
37: .IR bk (4).
38: .LP
39: Line discipline switching is accomplished with the TIOCSETD
40: .I ioctl:
41: .IP
42: .B "int ldisc = LDISC; ioctl(filedes, TIOCSETD, &ldisc);"
43: .LP
44: where LDISC is OTTYDISC for the standard tty driver, NTTYDISC for the new
45: driver and NETLDISC for the networking discipline.
46: The standard (currently old) tty driver is discipline 0 by convention.
47: The current line discipline can be obtained with the TIOCGETD ioctl.
48: Pending input is discarded when the line discipline is changed.
49: .PP
50: All of the low-speed asynchronous
51: communications ports can use any
52: of the available line disciplines, no matter what
53: hardware is involved.
54: The remainder of this section discusses the
55: \*(lqold\*(rq and \*(lqnew\*(rq disciplines.
56: .LP
57: .B "The control terminal."
58: .LP
59: When a terminal file is opened, it causes the process to wait until a
60: connection is established. In practice, user programs seldom open
61: these files; they are opened by
62: .IR init (8)
63: and become a user's standard input and output file.
64: .PP
65: If a process which has no control terminal opens a terminal file, then
66: that terminal file becomes the control terminal for that process.
67: The control terminal is thereafter inherited by a child process during a
68: .IR fork (2),
69: even if the control terminal is closed.
70: .LP
71: The file
72: .B /dev/tty
73: is, in each process, a synonym for a
74: .I "control terminal"
75: associated with that process. It is useful for programs that wish to
76: be sure of writing messages on the terminal
77: no matter how output has been redirected.
78: It can also be used for programs that demand a file name
79: for output, when typed output is desired
80: and it is tiresome to find out which terminal
81: is currently in use.
82: .LP
83: .B "Process groups."
84: .LP
85: As described more completely in
86: .IR jobs (3),
87: command processors such as
88: .IR csh (1)
89: can arbitrate the terminal between different
90: .I jobs
91: by placing related jobs in a single process group and associating this
92: process group with the terminal. A terminals associated process group
93: may be set using the TIOCSPGRP
94: .IR ioctl (2):
95: .IP
96: \fBioctl(fildes, TIOCSPGRP, &pgrp)\fR
97: .LP
98: or examined using TIOCGPGRP rather than TIOCSPGRP, returning the current
99: process group in
100: .I pgrp.
101: The new terminal driver aids in this arbitration by restricting access
102: to the terminal by processes which are not in the current process group;
103: see
104: .B "Job access control"
105: below.
106: .LP
107: .B "Modes."
108: .PP
109: The terminal drivers have three major modes, characterized by the
110: amount of processing on the input and output characters:
111: .IP cooked 10
112: The normal mode. In this mode lines of input are collected and input editing
113: is done. The edited line is made available when it is completed by
114: a newline
115: or when an EOT (control-D, hereafter ^D)
116: is entered.
117: A carriage return is usually made synonymous with newline in this mode,
118: and replaced with a newline whenever it is typed.
119: All driver functions
120: (input editing, interrupt generation,
121: output processing such as delay generation and tab expansion, etc.)
122: are available in this mode.
123: .IP CBREAK 10
124: This mode eliminates the character, word, and line editing input facilities,
125: making the input character available to the user program as it is typed.
126: Flow control, literal-next and interrupt processing are still done in this mode.
127: Output processing is done.
128: .IP RAW 10
129: This mode eliminates all input processing and makes all input characters
130: available as they are typed; no output processing is done either.
131: .PP
132: The style of input processing can also be very different when,
133: in the new terminal driver, a process asks for notification
134: via a SIGTTIN
135: .IR signal (2)
136: when input is ready to be read from the control terminal. In this case a
137: .IR read (2)
138: from the control terminal will never block, but rather
139: return an error indication (EIO) if there is no input available.
140: .LP
141: .B "Input editing."
142: .LP
143: A UNIX terminal ordinarily operates in full-duplex mode.
144: Characters may be typed at any time,
145: even while output is occurring, and are only lost when the
146: system's character input buffers become completely
147: choked, which is rare,
148: or when the user has accumulated the maximum allowed number of
149: input characters that have not yet been read by some program.
150: Currently this limit is 256 characters.
151: In the old terminal driver all the saved characters are thrown away
152: when the limit is reached, without notice; the new driver simply refuses
153: to accept any further input, and rings the terminal bell.
154: .PP
155: Input characters are normally accepted in either even or odd parity
156: with the parity bit being stripped off before the character is given to
157: the program. By clearing either the EVEN or ODD bit in the flags word
158: it is possible to have input characters with that parity discarded (see the
159: \fBSummary\fR below.)
160: .PP
161: In all of the line disciplines, it is possible to simulate terminal
162: input using the TIOCSTI ioctl, which takes, as its third argument,
163: the address of a character. The system pretends that this character
164: was typed on the argument terminal, which must be the control terminal except
165: for the super-user (this call is not in standard version 7 UNIX)..
166: .PP
167: Input characters are normally echoed by putting them in an output queue
168: as they arrive. This may be disabled by clearing the ECHO bit in the
169: flags word using the
170: .IR stty (2)
171: call or the TIOCSETN or TIOCSETP ioctls
172: (see the \fBSummary\fR below).
173: .PP
174: In cooked mode, terminal input is processed in units of lines.
175: A program attempting
176: to read will normally be suspended until an entire line has been
177: received
178: (but see the description of SIGTTIN in \fBModes\fR above and FIONREAD in
179: \fBSummary\fR below.)
180: No matter how many characters are requested
181: in the read call, at most one line will be returned.
182: It is not, however, necessary to read a whole line at
183: once; any number of characters may be
184: requested in a read, even one, without losing information.
185: .PP
186: During input, line editing is normally done, with the character `#'
187: logically erasing the last character typed and the character `@'
188: logically erasing the entire current input line.
189: These are often reset on crt's,
190: with ^H replacing #,
191: and ^U replacing @.
192: These characters
193: never erase beyond the beginning of the current input line or an ^D.
194: These characters may be entered literally by
195: preceding them with `\e\|'; in the old teletype driver both the `\e\|' and
196: the character entered literally will appear on the screen; in the new
197: driver the `\e\|' will normally disappear.
198: .PP
199: The drivers normally treat either a carriage return or a newline character
200: as terminating an input line, replacing the return with a newline and echoing
201: a return and a line feed.
202: If the CRMOD bit is cleared in the local mode word then the processing
203: for carriage return is disabled, and it is simply echoed as a return,
204: and does not terminate cooked mode input.
205: .PP
206: In the new driver there is a literal-next character ^V which can be typed
207: in both cooked and CBREAK mode preceding
208: .B any
209: character to prevent its special meaning. This is to be preferred to the
210: use of `\e\|' escaping erase and kill characters, but `\e\|' is (at least
211: temporarily) retained with its old function in the new driver for historical
212: reasons.
213: .PP
214: The new terminal driver also provides two other editing characters in
215: normal mode. The word-erase character, normally ^W, erases the preceding
216: word, but not any spaces before it. For the purposes of ^W, a word
217: is defined as a sequence of non-blank characters, with tabs counted as
218: blanks.
219: Finally, the reprint character, normally ^R, retypes the pending input beginning
220: on a new line. Retyping occurs automagically in cooked mode if characters
221: which would normally be erased from the screen are fouled by program output.
222: .LP
223: .B "Input echoing and redisplay"
224: .LP
225: In the old terminal driver, nothing special occurs when an erase character
226: is typed; the erase character is simply echoed. When a kill character
227: is typed it is echoed followed by a new-line (even if the character is
228: not killing the line, because it was preceded by a `\e\|'!.)
229: .PP
230: The new terminal driver has several modes for handling the echoing of
231: terminal input, controlled by bits in a local mode word.
232: .LP
233: .I "Hardcopy terminals."
234: When a hardcopy terminal is in use, the LPRTERA bit is normally set in
235: the local mode word. Characters which are logically erased are
236: then printed out backwards preceded by `\e\|' and followed by `/' in this mode.
237: .LP
238: .I "Crt terminals."
239: When a crt terminal is in use, the LCRTBS bit is normally set in the local
240: mode word. The terminal driver then echoes the proper number of erase
241: characters when input is erased; in the normal case where the erase
242: character is a ^H this causes the cursor of the terminal to back up
243: to where it was before the logically erased character was typed.
244: If the input has become fouled due to interspersed asynchronous output,
245: the input is automagically retyped.
246: .LP
247: .I "Erasing characters from a crt."
248: When a crt terminal is in use, the LCRTERA bit may be set to cause
249: input to be erased from the screen with a \*(lqbackspace-space-backspace\*(rq
250: sequence when character or word deleting sequences are used.
251: A LCRTKIL bit may be set as well, causing the input to
252: be erased in this manner on line kill sequences as well.
253: .LP
254: .I "Echoing of control characters."
255: If the LCTLECH bit is set in the local state word, then non-printing (control)
256: characters are normally echoed as ^X (for some X)
257: rather than being echoed unmodified; delete is echoed as ^?.
258: .LP
259: The normal modes for using the new terminal driver on crt terminals
260: are speed dependent.
261: At speeds less than 1200 baud, the LCRTERA and LCRTKILL processing
262: is painfully slow, so
263: .IR stty (1)
264: normally just sets LCRTBS and LCTLECH; at
265: speeds of 1200 baud or greater all of these bits are normally set.
266: .IR Stty (1)
267: summarizes these option settings and the use of the new terminal
268: driver as
269: \*(lqnewcrt.\*(rq
270: .LP
271: .B "Output processing."
272: .PP
273: When one or more
274: characters are written, they are actually transmitted
275: to the terminal as soon as previously-written characters
276: have finished typing.
277: (As noted above, input characters are normally
278: echoed by putting them in the output queue
279: as they arrive.)
280: When a process produces characters more rapidly than they can be typed,
281: it will be suspended when its output queue exceeds some limit.
282: When the queue has drained down to some threshold
283: the program is resumed.
284: Even parity is normally generated on output.
285: The EOT character is not transmitted in cooked mode to prevent terminals
286: that respond to it from hanging up; programs using raw or cbreak mode
287: should be careful.
288: .PP
289: The terminal drivers provide necessary processing for cooked and CBREAK mode
290: output including delay generation for certain special characters and parity
291: generation. Delays are available after backspaces ^H, form feeds ^L,
292: carriage returns ^M, tabs ^I and newlines ^J. The driver will also optionally
293: expand tabs into spaces, where the tab stops are assumed to be set every
294: eight columns. These functions are controlled by bits in the tty flags word;
295: see \fBSummary\fR below.
296: .PP
297: The terminal drivers provide for mapping between upper and lower case
298: on terminals lacking lower case, and for other special processing on
299: deficient terminals.
300: .PP
301: Finally, in the new terminal driver, there is a output flush character,
302: normally ^O, which sets the LFLUSHO bit in the local mode word, causing
303: subsequent output to be flushed until it is cleared by a program or more
304: input is typed. This character has effect in both cooked and CBREAK modes
305: and causes pending input to be retyped if there is any pending input.
306: Ioctls to flush the characters in the input and output queues TIOCFLUSH,
307: and to return the number of character still in the output queue
308: TIOCOUTQ are also available.
309: .LP
310: .B "Upper case terminals and Hazeltines"
311: .PP
312: If the LCASE bit is set in the tty flags, then
313: all upper-case letters are mapped into
314: the corresponding lower-case letter.
315: The upper-case letter may be generated by preceding
316: it by `\\'.
317: If the new terminal driver is being used,
318: then upper case letters
319: are preceded by a `\e\|' when output.
320: In addition, the following escape sequences can be generated
321: on output and accepted on input:
322: .PP
323: .nf
324: for \` | ~ { }
325: use \e\|\' \e\|! \e\|^ \e\|( \e\|)
326: .fi
327: .PP
328: To deal with Hazeltine terminals, which do not understand that ~ has
329: been made into an ASCII character, the LTILDE bit may be set in the local
330: mode word when using the new terminal driver; in this case the character
331: ~ will be replaced with the character \` on output.
332: .LP
333: .B "Flow control."
334: .PP
335: There are two characters (the stop character, normally ^S, and the
336: start character, normally ^Q) which cause output to be suspended and
337: resumed respectively. Extra stop characters typed when output
338: is already stopped have no effect, unless the start and stop characters
339: are made the same, in which case output resumes.
340: .PP
341: A bit in the flags word may be set to put the terminal into TANDEM mode.
342: In this mode the system produces a stop character (default ^S) when
343: the input queue is in danger of overflowing, and a start character (default
344: ^Q) when the input has drained sufficiently. This mode is useful
345: when the terminal is actually another machine that obeys the
346: conventions.
347: .LP
348: .B "Line control and breaks."
349: .LP
350: There are several
351: .I ioctl
352: calls available to control the state of the terminal line.
353: The TIOCSBRK ioctl will set the break bit in the hardware interface
354: causing a break condition to exist; this can be cleared (usually after a delay
355: with
356: .IR sleep (3))
357: by TIOCCBRK.
358: Break conditions in the input are reflected as a null character in RAW mode
359: or as the interrupt character in cooked or CBREAK mode.
360: The TIOCCDTR ioctl will clear the data terminal ready condition; it can
361: be set again by TIOCSDTR.
362: .PP
363: When the carrier signal from the dataset drops (usually
364: because the user has hung up his terminal) a
365: SIGHUP hangup signal is sent to the processes in the distinguished
366: process group of the terminal; this usually causes them to terminate
367: (the SIGHUP can be suppressed by setting the LNOHANG bit in the local
368: state word of the driver.)
369: Access to the terminal by other processes is then normally revoked,
370: so any further reads will fail, and programs that read a terminal and test for
371: end-of-file on their input will terminate appropriately.
372: .PP
373: When using an ACU
374: it is possible to ask that the phone line be hung up on the last close
375: with the TIOCHPCL ioctl; this is normally done on the outgoing line.
376: .LP
377: .B "Interrupt characters."
378: .PP
379: There are several characters that generate interrupts in cooked and CBREAK
380: mode; all are sent the processes in the control group of the terminal,
381: as if a TIOCGPGRP ioctl were done to get the process group and then a
382: .IR killpg (2)
383: system call were done,
384: except that these characters also flush pending input and output when
385: typed at a terminal
386: (\fI\z'a\`'la\fR TIOCFLUSH).
387: The characters shown here are the defaults; the field names in the structures
388: (given below)
389: are also shown.
390: The characters may be changed,
391: although this is not often done.
392: .IP ^?
393: \fBt_intrc\fR (Delete) generates a SIGINTR signal.
394: This is the normal way to stop a process which is no longer interesting,
395: or to regain control in an interactive program.
396: .IP ^\e
397: \fBt_quitc\fR (FS) generates a SIGQUIT signal.
398: This is used to cause a program to terminate and produce a core image,
399: if possible,
400: in the file
401: .B core
402: in the current directory.
403: .IP ^Z
404: \fBt_suspc\fR (EM) generates a SIGTSTP signal, which is used to suspend
405: the current process group.
406: .IP ^Y
407: \fBt_dstopc\fR (SUB) generates a SIGTSTP signal as ^Z does, but the
408: signal is sent when a program attempts to read the ^Y, rather than when
409: it is typed.
410: .LP
411: .B "Job access control."
412: .PP
413: When using the new terminal driver,
414: if a process which is not in the distinguished process group of its
415: control terminal attempts to read from that terminal its process group is
416: sent a SIGTTIN signal, which normally causes the members of that process group
417: to stop. If, however, the process is ignoring or holding SIGTTIN signal
418: is an orphan
419: .IR "" ( i.e.
420: its parent has exited and it has been inherited by the
421: .IR init (8)
422: process, or if it is a process in the middle of process creation using
423: .IR vfork (2)),
424: it is instead returned an end-of-file. Under older UNIX systems
425: these processes would typically have had their input files reset to
426: .B /dev/null,
427: so this is a compatible change.
428: .PP
429: When using the new terminal driver with the LTOSTOP bit set in the local
430: modes, a process is prohibited from writing on its control terminal if it is
431: not in the distinguished process group for that terminal.
432: Processes which are holding or ignoring SIGTTOU signals, which are
433: orphans, or which are in the middle of a
434: .IR vfork (2)
435: are excepted and allowed to produce output.
436: .LP
437: .B "Summary of modes."
438: .LP
439: Unfortunately, due to the evolution of the terminal driver,
440: there are 4 different structures which contain various portions of the
441: driver data. The first of these (\fBsgttyb\fR)
442: contains that part of the information
443: largely common between version 6 and version 7 UNIX systems.
444: The second contains additional control characters added in version 7.
445: The third is a word of local state peculiar to the new terminal driver,
446: and the fourth is another structure of special characters added for the
447: new driver. In the future a single structure may be made available
448: to programs which need to access all this information; most programs
449: need not concern themselves with all this state.
450: .LP
451: .Ul "Basic modes: sgtty."
452: .PP
453: The basic
454: .IR ioctl s
455: use the structure
456: defined in
457: .IR <sgtty.h> :
458: .PP
459: .ta .5i 1i
460: .nf
461: .ft 3
462: struct sgttyb {
463: char sg_ispeed;
464: char sg_ospeed;
465: char sg_stopbits;
466: char sg_erase;
467: char sg_kill;
468: short sg_flags;
469: };
470: .ft R
471: .fi
472: .PP
473: The
474: .I sg_ispeed
475: and
476: .I sg_ospeed
477: fields describe the input and output speeds of the
478: device according to the following table,
479: which corresponds to the DEC DH-11 interface.
480: If other hardware is used,
481: impossible speed changes are ignored.
482: Symbolic values in the table are as defined in
483: .IR <sgtty.h> .
484: .PP
485: .nf
486: .ta \w'B9600 'u +5n
487: B0 0 (hang up dataphone)
488: B50 1 50 baud
489: B75 2 75 baud
490: B110 3 110 baud
491: B134 4 134.5 baud
492: B150 5 150 baud
493: B200 6 200 baud
494: B300 7 300 baud
495: B600 8 600 baud
496: B1200 9 1200 baud
497: B1800 10 1800 baud
498: B2400 11 2400 baud
499: B4800 12 4800 baud
500: B9600 13 9600 baud
501: EXTA 14 External A
502: EXTB 15 External B
503: .fi
504: .DT
505: .PP
506: In the current configuration,
507: only 110, 150, 300 and 1200 baud are really supported on dial-up lines.
508: Code conversion and line control required for
509: IBM 2741's (134.5 baud)
510: must be implemented by the user's
511: program.
512: The half-duplex line discipline
513: required for the 202 dataset (1200 baud)
514: is not supplied; full-duplex 212 datasets work fine.
515: .PP
516: The
517: .I sg_stopbits
518: field of the argument structure
519: is used to specify the number of stop bits.
520: Specifying 1 gives 1 stop bit, 2 gives 2 stop bits, and
521: 3 gives 1.5 stop bits.
522: .PP
523: The
524: .I sg_erase
525: and
526: .I sg_kill
527: fields of the argument structure
528: specify the erase and kill characters respectively.
529: (Defaults are # and @.)
530: .PP
531: The
532: .I sg_flags
533: field of the argument structure
534: contains several bits that determine the
535: system's treatment of the terminal:
536: .PP
537: .ta \w'ALLDELAY 'u +\w'0100000 'u
538: .nf
539: ALLDELAY 0177400 Delay algorithm selection
540: BSDELAY 0100000 Select backspace delays (not implemented):
541: BS0 0
542: BS1 0100000
543: VTDELAY 0040000 Select form-feed and vertical-tab delays:
544: FF0 0
545: FF1 0100000
546: CRDELAY 0030000 Select carriage-return delays:
547: CR0 0
548: CR1 0010000
549: CR2 0020000
550: CR3 0030000
551: TBDELAY 0006000 Select tab delays:
552: TAB0 0
553: TAB1 0001000
554: TAB2 0004000
555: XTABS 0006000
556: NLDELAY 0001400 Select new-line delays:
557: NL0 0
558: NL1 0000400
559: NL2 0001000
560: NL3 0001400
561: EVENP 0000200 Even parity allowed on input (most terminals)
562: ODDP 0000100 Odd parity allowed on input
563: RAW 0000040 Raw mode: wake up on all characters, 8-bit interface
564: CRMOD 0000020 Map CR into LF; echo LF or CR as CR-LF
565: ECHO 0000010 Echo (full duplex)
566: LCASE 0000004 Map upper case to lower on input
567: CBREAK 0000002 Return each character as soon as typed
568: TANDEM 0000001 Automatic flow control
569: .DT
570: .fi
571: .PP
572: The delay bits specify how long
573: transmission stops to allow for mechanical or other movement
574: when certain characters are sent to the terminal.
575: In all cases a value of 0 indicates no delay.
576: .PP
577: Backspace delays are currently ignored but might
578: be used for Terminet 300's.
579: .PP
580: If a form-feed/vertical tab delay is specified,
581: it lasts for about 2 seconds.
582: .PP
583: Carriage-return delay type 1 lasts about .08 seconds
584: and is suitable for the Terminet 300.
585: Delay type 2 lasts about .16 seconds and is suitable
586: for the VT05 and the TI 700.
587: Delay type 3 is suitable for the concept-100 and pads lines
588: to be at least 9 characters at 9600 baud.
589: .PP
590: New-line delay type 1 is dependent on the current column
591: and is tuned for Teletype model 37's.
592: Type 2 is useful for the VT05 and is about .10 seconds.
593: Type 3 is unimplemented and is 0.
594: .PP
595: Tab delay type 1 is dependent on the amount of movement
596: and is tuned to the Teletype model
597: 37.
598: Type 3, called XTABS,
599: is not a delay at all but causes tabs to be replaced
600: by the appropriate number of spaces on output.
601: .PP
602: Input characters with the wrong parity, as determined by bits 200 and
603: 100, are ignored in cooked and CBREAK mode.
604: .PP
605: RAW
606: disables all processing save output flushing with LFLUSHO;
607: full 8 bits of input are given as soon as
608: it is available; all 8 bits are passed on output.
609: A break condition in the input is reported as a null character.
610: If the input queue overflows in raw mode it is discarded; this applies
611: to both new and old drivers.
612: .PP
613: CRMOD causes input carriage returns to be turned into
614: new-lines;
615: input of either CR or LF causes LF-CR both to
616: be echoed
617: (for terminals with a new-line function).
618: .PP
619: CBREAK is a sort of half-cooked (rare?) mode.
620: Programs can read each character as soon as typed, instead
621: of waiting for a full line;
622: all processing is done except the input editing:
623: character and word erase and line kill, input reprint,
624: and the special treatment of \e or EOT are disabled.
625: .PP
626: TANDEM mode causes the system to produce
627: a stop character (default ^S) whenever the input
628: queue is in danger of overflowing, and a start character
629: (default ^Q)
630: when the input queue has drained sufficiently.
631: It is useful for flow control when the `terminal'
632: is really another computer which understands the conventions.
633: .LP
634: .Ul "Basic ioctls"
635: .PP
636: In addition to the TIOCSETD and TIOCGETD disciplines discussed
637: in \fBLine disciplines\fR above,
638: a large number of other
639: .IR ioctl (2)
640: calls apply to terminals, and have the general form:
641: .PP
642: .B #include <sgtty.h>
643: .PP
644: .B ioctl(fildes, code, arg)
645: .br
646: .B struct sgttyb *arg;
647: .PP
648: The applicable codes are:
649: .IP TIOCGETP 15
650: Fetch the basic parameters associated with the terminal, and store
651: in the pointed-to \fIsgttyb\fR structure.
652: .IP TIOCSETP
653: Set the parameters according to the pointed-to \fIsgttyb\fR structure.
654: The interface delays until output is quiescent,
655: then throws away any unread characters,
656: before changing the modes.
657: .IP TIOCSETN
658: Set the parameters like TIOCSETP but do not delay or flush input.
659: Input is not preserved, however, when changing to or from RAW.
660: .PP
661: With the following codes the
662: .I arg
663: is ignored.
664: .IP TIOCEXCL 15
665: Set \*(lqexclusive-use\*(rq mode:
666: no further opens are permitted until the file has been closed.
667: .IP TIOCNXCL
668: Turn off \*(lqexclusive-use\*(rq mode.
669: .IP TIOCHPCL
670: When the file is closed for the last time,
671: hang up the terminal.
672: This is useful when the line is associated
673: with an ACU used to place outgoing calls.
674: .IP TIOCFLUSH
675: All characters waiting in input or output queues are flushed.
676: .LP
677: The remaining calls are not available in vanilla version 7 UNIX.
678: In cases where arguments are required, they are described; \fIarg\fR
679: should otherwise be given as 0.
680: .IP TIOCSTI 15
681: the argument is the address of a character which the system
682: pretends was typed on the terminal.
683: .IP TIOCSBRK 15
684: the break bit is set in the terminal.
685: .IP TIOCCBRK
686: the break bit is cleared.
687: .IP TIOCSDTR
688: data terminal ready is set.
689: .IP TIOCCDTR
690: data terminal ready is cleared.
691: .IP TIOCGPGRP
692: arg is the address of a word into which is placed the process group
693: number of the control terminal.
694: .IP TIOCSPGRP
695: arg is a word (typically a process id) which becomes the process
696: group for the control terminal.
697: .IP FIONREAD
698: returns in the long integer whose address is arg the number
699: of immediately readable characters from the argument unit.
700: This works for files, pipes, and terminals, but not (yet)
701: for multiplexed channels.
702: .LP
703: .Ul Tchars
704: .PP
705: The second structure associated with each terminal specifies
706: characters that are special in both the old and new terminal interfaces:
707: The following structure is defined in
708: .IR <sys/ioctl.h> ,
709: which is automatically included in
710: .IR <sgtty.h> :
711: .PP
712: .nf
713: .ft 3
714: .ta .5i 1i 2i
715: struct tchars {
716: char t_intrc; /* interrupt */
717: char t_quitc; /* quit */
718: char t_startc; /* start output */
719: char t_stopc; /* stop output */
720: char t_eofc; /* end-of-file */
721: char t_brkc; /* input delimiter (like nl) */
722: };
723: .DT
724: .fi
725: .ft R
726: .PP
727: The default values for these characters are
728: ^?, ^\e\|, ^Q, ^S, ^D, and \-1.
729: A character value of \-1
730: eliminates the effect of that character.
731: The
732: .I t_brkc
733: character, by default \-1,
734: acts like a new-line in that it terminates a `line,'
735: is echoed, and is passed to the program.
736: The `stop' and `start' characters may be the same,
737: to produce a toggle effect.
738: It is probably counterproductive to make
739: other special characters (including erase and kill)
740: identical.
741: The applicable ioctl calls are:
742: .IP TIOCGETC 12
743: Get the special characters and put them in the specified structure.
744: .IP TIOCSETC 12
745: Set the special characters to those given in the structure.
746: .LP
747: .Ul "Local mode"
748: .PP
749: The third structure associated with each terminal is a local mode word;
750: except for the LNOHANG bit, this word is interpreted only when the new
751: driver is in use.
752: The bits of the local mode word are:
753: .sp
754: .nf
755: LCRTBS 000001 Backspace on erase rather than echoing erase
756: LPRTERA 000002 Printing terminal erase mode
757: LCRTERA 000004 Erase character echoes as backspace-space-backspace
758: LTILDE 000010 Convert ~ to \` on output (for Hazeltine terminals)
759: LMDMBUF 000020 Stop/start output when carrier drops
760: LLITOUT 000040 Suppress output translations
761: LTOSTOP 000100 Send SIGTTOU for background output
762: LFLUSHO 000200 Output is being flushed
763: LNOHANG 000400 Don't send hangup when carrier drops
764: LETXACK 001000 Diablo style buffer hacking (unimplemented)
765: LCRTKIL 002000 BS-space-BS erase entire line on line kill
766: LINTRUP 004000 Generate interrupt SIGTINT when input ready to read
767: LCTLECH 010000 Echo input control chars as ^X, delete as ^?
768: LPENDIN 020000 Retype pending input at next read or input character
769: LDECCTQ 040000 Only ^Q restarts output after ^S, like DEC systems
770: .fi
771: .sp
772: The applicable
773: .I ioctl
774: functions are:
775: .IP TIOCLBIS 15
776: arg is the address of a
777: mask which is the bits to be set in the local mode word.
778: .IP TIOCLBIC
779: arg is the address of a mask of bits to be cleared in the local mode word.
780: .IP TIOCLSET
781: arg is the address of a mask to be placed in the local mode word.
782: .IP TIOCLGET
783: arg is the address of a word into which the current mask is placed.
784: .LP
785: .Ul "Local special chars"
786: .PP
787: The
788: final structure associated with each terminal is the
789: .I ltchars
790: structure which defines interrupt characters
791: for the new terminal driver.
792: Its structure is:
793: .nf
794: .sp
795: .ta .5i 1i 2i
796: .ft B
797: struct ltchars {
798: char t_suspc; /* stop process signal */
799: char t_dstopc; /* delayed stop process signal */
800: char t_rprntc; /* reprint line */
801: char t_flushc; /* flush output (toggles) */
802: char t_werasec; /* word erase */
803: char t_lnextc; /* literal next character */
804: };
805: .ft R
806: .fi
807: .sp
808: The default values for these characters are ^Z, ^Y, ^R, ^O, ^W, and ^V.
809: A value of \-1 disables the character.
810: .PP
811: The applicable \fIioctl\fR functions are:
812: .IP TIOCSLTC 12
813: args is the address of a
814: .I ltchars
815: structure which defines the new local special characters.
816: .IP TIOCGLTC 12
817: args is the address of a
818: .I ltchars
819: structure into which is placed the current set of local special characters.
820: .SH FILES
821: /dev/tty
822: .br
823: /dev/tty*
824: .br
825: /dev/console
826: .SH SEE ALSO
827: csh(1), stty(1),
828: ioctl(2), signal(2), sigsys(2), stty(2),
829: getty(8), init(8), newtty(4)
830: .SH BUGS
831: Half-duplex terminals are not supported.
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