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--- old/usr/src/man/man7i/termio.7i.man.txt
+++ new/usr/src/man/man7i/termio.7i.man.txt
1 1 TERMIO(7I) Ioctl Requests TERMIO(7I)
2 2
3 3 NAME
4 4 termio - general terminal interface
5 5
6 6 SYNOPSIS
7 7 #include <termio.h>
8 8
9 9 ioctl(int fildes, int request, struct termio *arg);
10 10
11 11 ioctl(int fildes, int request, int arg);
12 12
13 13 #include <termios.h>
14 14
15 15 ioctl(int fildes, int request, struct termios *arg);
16 16
17 17 DESCRIPTION
18 18 This release supports a general interface for asynchronous communications
19 19 ports that is hardware-independent. The user interface to this
20 20 functionality is using function calls (the preferred interface) described
21 21 in termios(3C) or ioctl() commands described in this section. This
22 22 section also discusses the common features of the terminal subsystem
23 23 which are relevant with both user interfaces.
24 24
25 25 When a terminal file is opened, it normally causes the process to wait
26 26 until a connection is established. In practice, user programs seldom
27 27 open terminal files; they are opened by the system and become a user's
28 28 standard input, output, and error files. The first terminal file opened
29 29 by the session leader that is not already associated with a session
30 30 becomes the controlling terminal for that session. The controlling
31 31 terminal plays a special role in handling quit and interrupt signals, as
32 32 discussed below. The controlling terminal is inherited by a child
33 33 process during a fork(2). A process can break this association by
34 34 changing its session using setsid(2).
35 35
36 36 A terminal associated with one of these files ordinarily operates in
37 37 full-duplex mode. Characters may be typed at any time, even while output
38 38 is occurring, and are only lost when the character input buffers of the
39 39 system become completely full, which is rare. For example, the number of
40 40 characters in the line discipline buffer may exceed {MAX_CANON} and
41 41 IMAXBEL (see below) is not set, or the user may accumulate {MAX_INPUT}
42 42 number of input characters that have not yet been read by some program.
43 43 When the input limit is reached, all the characters saved in the buffer
44 44 up to that point are thrown away without notice.
45 45
46 46 Session Management (Job Control)
47 47 A control terminal will distinguish one of the process groups in the
48 48 session associated with it to be the foreground process group. All other
49 49 process groups in the session are designated as background process
50 50 groups. This foreground process group plays a special role in handling
51 51 signal-generating input characters, as discussed below. By default, when
52 52 a controlling terminal is allocated, the controlling process's process
53 53 group is assigned as foreground process group.
54 54
55 55 Background process groups in the controlling process's session are
56 56 subject to a job control line discipline when they attempt to access
57 57 their controlling terminal. Process groups can be sent signals that will
58 58 cause them to stop, unless they have made other arrangements. An
59 59 exception is made for members of orphaned process groups.
60 60
61 61 An orphaned process group is one where the process group (see getpgid(2))
62 62 has no members with a parent in a different process group but sharing the
63 63 same controlling terminal. When a member of an orphaned process group
64 64 attempts to access its controlling terminal, EIO is returned because
65 65 there would be no way to restart the process if it were stopped on one of
66 66 these signals.
67 67
68 68 If a member of a background process group attempts to read its
69 69 controlling terminal, its process group will be sent a SIGTTIN signal,
70 70 which will normally cause the members of that process group to stop. If,
71 71 however, the process is ignoring or holding SIGTTIN, or is a member of an
72 72 orphaned process group, the read will fail with errno set to EIO, and no
73 73 signal is sent.
74 74
75 75 If a member of a background process group attempts to write its
76 76 controlling terminal and the TOSTOP bit is set in the c_lflag field, its
77 77 process group is sent a SIGTTOU signal, which will normally cause the
78 78 members of that process group to stop. If, however, the process is
79 79 ignoring or holding SIGTTOU, the write will succeed. If the process is
80 80 not ignoring or holding SIGTTOU and is a member of an orphaned process
81 81 group, the write will fail with errno set to EIO, and no signal will be
82 82 sent.
83 83
84 84 If TOSTOP is set and a member of a background process group attempts to
85 85 ioctl() its controlling terminal, and that ioctl() will modify terminal
86 86 parameters (for example, TCSETA, TCSETAW, TCSETAF, or TIOCSPGRP), its
87 87 process group will be sent a SIGTTOU signal, which will normally cause
88 88 the members of that process group to stop. If, however, the process is
89 89 ignoring or holding SIGTTOU, the ioctl will succeed. If the process is
90 90 not ignoring or holding SIGTTOU and is a member of an orphaned process
91 91 group, the write will fail with errno set to EIO, and no signal will be
92 92 sent.
93 93
94 94 Canonical Mode Input Processing
95 95 Normally, terminal input is processed in units of lines. A line is
96 96 delimited by a newline (ASCII LF) character, an end-of-file (ASCII EOT)
97 97 character, or an end-of-line character. This means that a program
98 98 attempting to read will block until an entire line has been typed. Also,
99 99 no matter how many characters are requested in the read call, at most one
100 100 line will be returned. It is not necessary, however, to read a whole
101 101 line at once; any number of characters may be requested in a read, even
102 102 one, without losing information.
103 103
104 104 During input, erase, erase2, and kill processing is normally done. The
105 105 ERASE and ERASE2 character (by default, the character DEL for ERASE and
106 106 Control-h for ERASE2) erases the last character typed. The WERASE
107 107 character (the character Control-w) erases the last "word" typed in the
108 108 current input line (but not any preceding spaces or tabs). A "word" is
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109 109 defined as a sequence of non-blank characters, with tabs counted as
110 110 blanks. None of ERASE or ERASE2 or WERASE will erase beyond the
111 111 beginning of the line. The KILL character (by default, the character
112 112 NAK) kills (deletes) the entire input line, and optionally outputs a
113 113 newline character. All these characters operate on a key stroke basis,
114 114 independent of any backspacing or tabbing that may have been done. The
115 115 REPRINT character (the character Control-r) prints a newline followed by
116 116 all characters that have not been read. Reprinting also occurs
117 117 automatically if characters that would normally be erased from the screen
118 118 are fouled by program output. The characters are reprinted as if they
119 - were being echoed; consequencely, if ECHO is not set, they are not
119 + were being echoed; consequently, if ECHO is not set, they are not
120 120 printed.
121 121
122 122 The ERASE, ERASE2, and KILL characters may be entered literally by
123 123 preceding them with the escape character. In this case, the escape
124 124 character is not read. The erase, erase2, and kill characters may be
125 125 changed.
126 126
127 127 Non-canonical Mode Input Processing
128 128 In non-canonical mode input processing, input characters are not
129 129 assembled into lines, and erase and kill processing does not occur. The
130 130 MIN and TIME values are used to determine how to process the characters
131 131 received.
132 132
133 133 MIN represents the minimum number of characters that should be received
134 134 when the read is satisfied (that is, when the characters are returned to
135 135 the user). TIME is a timer of 0.10-second granularity that is used to
136 136 timeout bursty and short-term data transmissions. The four possible
137 137 values for MIN and TIME and their interactions are described below.
138 138
139 139 Case A: MIN > 0, TIME > 0 In this case, TIME serves as an intercharacter
140 140 timer and is activated after the first
141 141 character is received. Since it is an
142 142 intercharacter timer, it is reset after a
143 143 character is received. The interaction
144 144 between MIN and TIME is as follows: as soon as
145 145 one character is received, the intercharacter
146 146 timer is started. If MIN characters are
147 147 received before the intercharacter timer
148 148 expires (note that the timer is reset upon
149 149 receipt of each character), the read is
150 150 satisfied. If the timer expires before MIN
151 151 characters are received, the characters
152 152 received to that point are returned to the
153 153 user. Note that if TIME expires, at least one
154 154 character will be returned because the timer
155 155 would not have been enabled unless a character
156 156 was received. In this case (MIN > 0, TIME >
157 157 0), the read sleeps until the MIN and TIME
158 158 mechanisms are activated by the receipt of the
159 159 first character. If the number of characters
160 160 read is less than the number of characters
161 161 available, the timer is not reactivated and
162 162 the subsequent read is satisfied immediately.
163 163
164 164 Case B: MIN > 0, TIME = 0 In this case, since the value of TIME is zero,
165 165 the timer plays no role and only MIN is
166 166 significant. A pending read is not satisfied
167 167 until MIN characters are received (the pending
168 168 read sleeps until MIN characters are
169 169 received). A program that uses this case to
170 170 read record based terminal I/O may block
171 171 indefinitely in the read operation.
172 172
173 173 Case C: MIN = 0, TIME > 0 In this case, since MIN 0, TIME no longer
174 174 represents an intercharacter timer: it now
175 175 serves as a read timer that is activated as
176 176 soon as a read(2) is done. A read is
177 177 satisfied as soon as a single character is
178 178 received or the read timer expires. Note
179 179 that, in this case, if the timer expires, no
180 180 character is returned. If the timer does not
181 181 expire, the only way the read can be satisfied
182 182 is if a character is received. In this case,
183 183 the read will not block indefinitely waiting
184 184 for a character; if no character is received
185 185 within TIME *.10 seconds after the read is
186 186 initiated, the read returns with zero
187 187 characters.
188 188
189 189 Case D: MIN = 0, TIME = 0 In this case, return is immediate. The
190 190 minimum of either the number of characters
191 191 requested or the number of characters
192 192 currently available is returned without
193 193 waiting for more characters to be input.
194 194
195 195 Comparing Different Cases of MIN, TIME Interaction
196 196 Some points to note about MIN and TIME:
197 197
198 198 o In the following explanations, note that the interactions of MIN
199 199 and TIME are not symmetric. For example, when MIN > 0 and TIME =
200 200 0, TIME has no effect. However, in the opposite case, where MIN =
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201 201 0 and TIME > 0, both MIN and TIME play a role in that MIN is
202 202 satisfied with the receipt of a single character.
203 203
204 204 o Also note that in case A (MIN > 0, TIME > 0), TIME represents an
205 205 intercharacter timer, whereas in case C (MIN = 0, TIME > 0), TIME
206 206 represents a read timer.
207 207
208 208 These two points highlight the dual purpose of the MIN/TIME feature.
209 209 Cases A and B, where MIN > 0, exist to handle burst mode activity (for
210 210 example, file transfer programs), where a program would like to process
211 - at least MIN characters at a time. In case A, the inteercharacter timer
211 + at least MIN characters at a time. In case A, the intercharacter timer
212 212 is activated by a user as a safety measure; in case B, the timer is
213 213 turned off.
214 214
215 215 Cases C and D exist to handle single character, timed transfers. These
216 216 cases are readily adaptable to screen-based applications that need to
217 217 know if a character is present in the input queue before refreshing the
218 218 screen. In case C, the read is timed, whereas in case D, it is not.
219 219
220 220 Another important note is that MIN is always just a minimum. It does not
221 221 denote a record length. For example, if a program does a read of 20
222 222 bytes, MIN is 10, and 25 characters are present, then 20 characters will
223 223 be returned to the user.
224 224
225 225 Writing Characters
226 226 When one or more characters are written, they are transmitted to the
227 227 terminal as soon as previously written characters have finished typing.
228 - nputt characters are echoed as they are typed if echoing has been
228 + Input characters are echoed as they are typed if echoing has been
229 229 enabled. If a process produces characters more rapidly than they can be
230 230 typed, it will be suspended when its output queue exceeds some limit.
231 231 When the queue is drained down to some threshold, the program is resumed.
232 232
233 233 Special Characters
234 234 Certain characters have special functions on input. These functions and
235 235 their default character values are summarized as follows:
236 236
237 237 INTR (Control-c or ASCII ETX) generates a SIGINT signal. SIGINT is
238 238 sent to all foreground processes associated with the controlling
239 239 terminal. Normally, each such process is forced to terminate,
240 240 but arrangements may be made either to ignore the signal or to
241 241 receive a trap to an agreed upon location. (See
242 242 signal.h(3HEAD)).
243 243
244 244 QUIT (Control-| or ASCII FS) generates a SIGQUIT signal. Its
245 245 treatment is identical to the interrupt signal except that,
246 246 unless a receiving process has made other arrangements, it will
247 247 not only be terminated but a core image file (called core) will
248 248 be created in the current working directory.
249 249
250 250 ERASE (DEL) erases the preceding character. It does not erase beyond
251 251 the start of a line, as delimited by a NL, EOF, EOL, or EOL2
252 252 character.
253 253
254 254 ERASE2 (Control-h or ASCII BS) erases the preceding character, with
255 255 behaviour identical to that of ERASE.
256 256
257 257 WERASE (Control-w or ASCII ETX) erases the preceding "word". It does
258 258 not erase beyond the start of a line, as delimited by a NL, EOF,
259 259 EOL, or EOL2 character.
260 260
261 261 KILL (Control-u or ASCII NAK) deletes the entire line, as delimited
262 262 by a NL, EOF, EOL, or EOL2 character.
263 263
264 264 REPRINT (Control-r or ASCII DC2) reprints all characters, preceded by a
265 265 newline, that have not been read.
266 266
267 267 EOF (Control-d or ASCII EOT) may be used to generate an end-of-file
268 268 from a terminal. When received, all the characters waiting to
269 269 be read are immediately passed to the program, without waiting
270 270 for a newline, and the EOF is discarded. Thus, if no characters
271 271 are waiting (that is, the EOF occurred at the beginning of a
272 272 line) zero characters are passed back, which is the standard
273 273 end-of-file indication. Unless escaped, the EOF character is
274 274 not echoed. Because EOT is the default EOF character, this
275 275 prevents terminals that respond to EOT from hanging up.
276 276
277 277 NL (ASCII LF) is the normal line delimiter. It cannot be changed
278 278 or escaped.
279 279
280 280 EOL (ASCII NULL) is an additional line delimiter, like NL. It is
281 281 not normally used.
282 282
283 283 EOL2 is another additional line delimiter.
284 284
285 285 SWTCH (Control-z or ASCII EM) Header file symbols related to this
286 286 special character are present for compatibility purposes only
287 287 and the kernel takes no special action on matching SWTCH (except
288 288 to discard the character).
289 289
290 290 SUSP (Control-z or ASCII SUB) generates a SIGTSTP signal. SIGTSTP
291 291 stops all processes in the foreground process group for that
292 292 terminal.
293 293
294 294 DSUSP (Control-y or ASCII EM). It generates a SIGTSTP signal as SUSP
295 295 does, but the signal is sent when a process in the foreground
296 296 process group attempts to read the DSUSP character, rather than
297 297 when it is typed.
298 298
299 299 STOP (Control-s or ASCII DC3) can be used to suspend output
300 300 temporarily. It is useful with CRT terminals to prevent output
301 301 from disappearing before it can be read. While output is
302 302 suspended, STOP characters are ignored and not read.
303 303
304 304 START (Control-q or ASCII DC1) is used to resume output. Output has
305 305 been suspended by a STOP character. While output is not
306 306 suspended, START characters are ignored and not read.
307 307
308 308 DISCARD (Control-o or ASCII SI) causes subsequent output to be
309 309 discarded. Output is discarded until another DISCARD character
310 310 is typed, more input arrives, or the condition is cleared by a
311 311 program.
312 312
313 313 STATUS (Control-t or ASCII DC4) generates a SIGINFO signal. Processes
314 314 with a handler will output status information when they receive
315 315 SIGINFO, for example, dd(1M). If a process does not have a
316 316 SIGINFO handler, the signal will be ignored.
317 317
318 318 LNEXT (Control-v or ASCII SYN) causes the special meaning of the next
319 319 character to be ignored. This works for all the special
320 320 characters mentioned above. It allows characters to be input
321 321 that would otherwise be interpreted by the system (for example
322 322 KILL, QUIT). The character values for INTR, QUIT, ERASE,
323 323 ERASE2, WERASE, KILL, REPRINT, EOF, EOL, EOL2, SWTCH, SUSP,
324 324 DSUSP, STOP, START, DISCARD, STATUS, and LNEXT may be changed to
325 325 suit individual tastes. If the value of a special control
326 326 character is _POSIX_VDISABLE (0), the function of that special
327 327 control character is disabled. The ERASE, ERASE2, KILL, and EOF
328 328 characters may be escaped by a preceding backslash (\)
329 329 character, in which case no special function is done. Any of
330 330 the special characters may be preceded by the LNEXT character,
331 331 in which case no special function is done.
332 332
333 333 Modem Disconnect
334 334 When a modem disconnect is detected, a SIGHUP signal is sent to the
335 335 terminal's controlling process. Unless other arrangements have been
336 336 made, these signals cause the process to terminate. If SIGHUP is ignored
337 337 or caught, any subsequent read returns with an end-of-file indication
338 338 until the terminal is closed.
339 339
340 340 If the controlling process is not in the foreground process group of the
341 341 terminal, a SIGTSTP is sent to the terminal's foreground process group.
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342 342 Unless other arrangements have been made, these signals cause the
343 343 processes to stop.
344 344
345 345 Processes in background process groups that attempt to access the
346 346 controlling terminal after modem disconnect while the terminal is still
347 347 allocated to the session will receive appropriate SIGTTOU and SIGTTIN
348 348 signals. Unless other arrangements have been made, this signal causes
349 349 the processes to stop.
350 350
351 351 The controlling terminal will remain in this state until it is
352 - reinitialized ithh a successful open by the controlling process, or
352 + reinitialized with a successful open by the controlling process, or
353 353 deallocated by the controlling process.
354 354
355 355 Terminal Parameters
356 356 The parameters that control the behavior of devices and modules providing
357 357 the termios interface are specified by the termios structure defined by
358 358 <termios.h>. Several ioctl(2) system calls that fetch or change these
359 359 parameters use this structure that contains the following members:
360 360
361 361 tcflag_t c_iflag; /* input modes */
362 362 tcflag_t c_oflag; /* output modes */
363 363 tcflag_t c_cflag; /* control modes */
364 364 tcflag_t c_lflag; /* local modes */
365 365 cc_t c_cc[NCCS]; /* control chars */
366 366
367 367 The special control characters are defined by the array c_cc. The
368 368 symbolic name NCCS is the size of the Control-character array and is also
369 369 defined by <termios.h>. The relative positions, subscript names, and
370 370 typical default values for each function are as follows:
371 371
372 372 Relative Position Subscript Name Typical Default Value
373 373 0 VINTR ETX
374 374 1 VQUIT FS
375 375 2 VERASE DEL
376 376 3 VKILL NAK
377 377 4 VEOF EOT
378 378 5 VEOL NUL
379 379 6 VEOL2 NUL
380 380 7 VWSTCH NUL
381 381 8 VSTART NUL
382 382 9 VSTOP DC3
383 383 10 VSUSP SUB
384 384 11 VDSUSP EM
385 385 12 VREPRINT DC2
386 386 13 VDISCARD SI
387 387 14 VWERASE ETB
388 388 15 VLNEXT SYN
389 389 16 VSTATUS DC4
390 390 17 VERASE2 BS
391 391 18-19 Reserved
392 392
393 393 Input Modes
394 394 The c_iflag field describes the basic terminal input control:
395 395
396 396 IGNBRK Ignore break condition.
397 397 BRKINT Signal interrupt on break.
398 398 IGNPAR Ignore characters with parity errors.
399 399 PARMRK Mark parity errors.
400 400 INPCK Enable input parity check.
401 401 ISTRIP Strip character.
402 402 INLCR Map NL to CR on input.
403 403 IGNCR Ignore CR.
404 404 ICRNL Map CR to NL on input.
405 405 IUCLC Map upper-case to lower-case on input.
406 406 IXON Enable start/stop output control.
407 407 IXANY Enable any character to restart output.
408 408 IXOFF Enable start/stop input control.
409 409 IMAXBEL Echo BEL on input line too long.
410 410
411 411 If IGNBRK is set, a break condition (a character framing error with data
412 412 all zeros) detected on input is ignored, that is, not put on the input
413 413 queue and therefore not read by any process. If IGNBRK is not set and
414 414 BRKINT is set, the break condition shall flush the input and output
415 415 queues and if the terminal is the controlling terminal of a foreground
416 416 process group, the break condition generates a single SIGINT signal to
417 417 that foreground process group. If neither IGNBRK nor BRKINT is set, a
418 418 break condition is read as a single `\0' (ASCII NULL) character, or if
419 419 PARMRK is set, as `\377', `\0', c, where `\377' is a single character
420 420 with value 377 octal (0xff hex, 255 decimal), `\0' is a single character
421 421 with value 0, and c is the errored character received.
422 422
423 423 If IGNPAR is set, a byte with framing or parity errors (other than break)
424 424 is ignored.
425 425
426 426 If PARMRK is set, and IGNPAR is not set, a byte with a framing or parity
427 427 error (other than break) is given to the application as the three-
428 428 character sequence: `\377', `\0', c, where `\377' is a single character
429 429 with value 377 octal (0xff hex, 255 decimal), `\0' is a single character
430 430 with value 0, and c is the errored character received. To avoid
431 431 ambiguity in this case, if ISTRIP is not set, a valid character of `\377'
432 432 is given to the application as `\377'. If neither IGNPAR nor PARMRK is
433 433 set, a framing or parity error (other than break) is given to the
434 434 application as a single `\0' (ASCII NULL) character.
435 435
436 436 If INPCK is set, input parity checking is enabled. If INPCK is not set,
437 437 input parity checking is disabled. This allows output parity generation
438 438 without input parity errors. Note that whether input parity checking is
439 439 enabled or disabled is independent of whether parity detection is enabled
440 440 or disabled. If parity detection is enabled but input parity checking is
441 441 disabled, the hardware to which the terminal is connected will recognize
442 442 the parity bit, but the terminal special file will not check whether this
443 443 is set correctly or not.
444 444
445 445 If ISTRIP is set, valid input characters are first stripped to seven
446 446 bits, otherwise all eight bits are processed.
447 447
448 448 If INLCR is set, a received NL character is translated into a CR
449 449 character. If IGNCR is set, a received CR character is ignored (not
450 450 read). Otherwise, if ICRNL is set, a received CR character is translated
451 451 into a NL character.
452 452
453 453 If IUCLC is set, a received upper case, alphabetic character is
454 454 translated into the corresponding lower case character.
455 455
456 456 If IXON is set, start/stop output control is enabled. A received STOP
457 457 character suspends output and a received START character restarts output.
458 458 The STOP and START characters will not be read, but will merely perform
459 459 flow control functions. If IXANY is set, any input character restarts
460 460 output that has been suspended.
461 461
462 462 If IXOFF is set, the system transmits a STOP character when the input
463 463 queue is nearly full, and a START character when enough input has been
464 464 read so that the input queue is nearly empty again.
465 465
466 466 If IMAXBEL is set, the ASCII BEL character is echoed if the input stream
467 467 overflows. Further input is not stored, but any input already present in
468 468 the input stream is not disturbed. If IMAXBEL is not set, no BEL
469 469 character is echoed, and all input present in the input queue is
470 470 discarded if the input stream overflows.
471 471
472 472 Output Modes
473 473 The c_oflag field specifies the system treatment of output:
474 474
475 475 OPOST Post-process output.
476 476 OLCUC Map lower case to upper on output.
477 477 ONLCR Map NL to CR-NL on output.
478 478 OCRNL Map CR to NL on output.
479 479 ONOCR No CR output at column 0.
480 480 ONLRET NL performs CR function.
481 481 OFILL Use fill characters for delay.
482 482 OFDEL Fill is DEL, else INULL.
483 483 NLDLY Select newline delays:
484 484 NL0
485 485 NL1
486 486 CRDLY Select carriage-return delays:
487 487 CR0
488 488 CR1
489 489 CR2
490 490 CR3
491 491 TABDLY Select horizontal tab delays or tab expansion:
492 492 TAB0
493 493 TAB1
494 494 TAB2
495 495 TAB3 Expand tabs to spaces
496 496 XTABS Expand tabs to spaces
497 497 BSDLY Select backspace delays:
498 498 BS0
499 499 BS1
500 500 VTDLY Select vertical tab delays:
501 501 VT0
502 502 VT1
503 503 FFDLY Select form feed delays:
504 504 FF0
505 505 FF1
506 506
507 507 If OPOST is set, output characters are post-processed as indicated by the
508 508 remaining flags; otherwise, characters are transmitted without change.
509 509
510 510 If OLCUC is set, a lower case alphabetic character is transmitted as the
511 511 corresponding upper case character. This function is often used in
512 512 conjunction with IUCLC.
513 513
514 514 If ONLCR is set, the NL character is transmitted as the CR-NL character
515 515 pair. If OCRNL is set, the CR character is transmitted as the NL
516 516 character. If ONOCR is set, no CR character is transmitted when at
517 517 column 0 (first position). If ONRET is set, the NL character is assumed
518 518 to do the carriage-return function; the column pointer is set to 0 and
519 519 the delays specified for CR are used. Otherwise, the NL character is
520 520 assumed to do just the line-feed function; the column pointer remains
521 521 unchanged. The column pointer is also set to 0 if the CR character is
522 522 actually transmitted.
523 523
524 524 The delay bits specify how long transmission stops to allow for
525 525 mechanical or other movement when certain characters are sent to the
526 526 terminal. In all cases, a value of 0 indicates no delay. If OFILL is
527 527 set, fill characters are transmitted for delay instead of a timed delay.
528 528 This is useful for high baud rate terminals that need only a minimal
529 529 delay. If OFDEL is set, the fill character is DEL; otherwise it is NULL.
530 530
531 531 If a form-feed or vertical-tab delay is specified, it lasts for about 2
532 532 seconds.
533 533
534 534 Newline delay lasts about 0.10 seconds. If ONLRET is set, the carriage-
535 535 return delays are used instead of the newline delays. If OFILL is set,
536 536 two fill characters are transmitted.
537 537
538 538 Carriage-return delay type 1 is dependent on the current column position,
539 539 type 2 is about 0.10 seconds, and type 3 is about 0.15 seconds. If OFILL
540 540 is set, delay type 1 transmits two fill characters, and type 2 transmits
541 541 four fill characters.
542 542
543 543 Horizontal-tab delay type 1 is dependent on the current column position.
544 544 Type 2 is about 0.10 seconds. Type 3 specifies that tabs are to be
545 545 expanded into spaces. If OFILL is set, two fill characters are
546 546 transmitted for any delay.
547 547
548 548 Backspace delay lasts about 0.05 seconds. If OFILL is set, one fill
549 549 character is transmitted.
550 550
551 551 The actual delays depend on line speed and system load.
552 552
553 553 Control Modes
554 554 The c_cflag field describes the hardware control of the terminal:
555 555
556 556 CBAUD Baud rate:
557 557 B0 Hang up
558 558 B50 50 baud
559 559 B75 75 baud
560 560 B110 110 baud
561 561 B134 134 baud
562 562 B150 150 baud
563 563 B200 200 baud
564 564 B300 300 baud
565 565 B600 600 baud
566 566 B1200 1200 baud
567 567 B1800 1800 baud
568 568 B2400 2400 baud
569 569 B4800 4800 baud
570 570 B9600 9600 baud
571 571 B19200 19200 baud
572 572 EXTA External A
573 573 B38400 38400 baud
574 574 EXTB External B
575 575 B57600 57600 baud
576 576 B76800 76800 baud
577 577 B115200 115200 baud
578 578 B153600 153600 baud
579 579 B230400 230400 baud
580 580 B307200 307200 baud
581 581 B460800 460800 baud
582 582
583 583 CSIZE Character size:
584 584 CS5 5 bits
585 585 CS6 6 bits
586 586 CS7 7 bits
587 587 CS8 8 bits
588 588 CSTOPB Send two stop bits, else one
589 589 CREAD Enable receiver
590 590 PARENB Parity enable
591 591 PARODD Odd parity, else even
592 592 HUPCL Hang up on last close
593 593 CLOCAL Local line, else dial-up
594 594 CIBAUD Input baud rate, if different from output rate
595 595 PAREXT Extended parity for mark and space parity
596 596 CRTSXOFF Enable inbound hardware flow control
597 597 CRTSCTS Enable outbound hardware flow control
598 598 CBAUDEXT Bit to indicate output speed > B38400
599 599 CIBAUDEXT Bit to indicate input speed > B38400
600 600
601 601 The CBAUD bits together with the CBAUDEXT bit specify the output baud
602 602 rate. To retrieve the output speed from the termios structure pointed to
603 603 by termios_p see the following code segment.
604 604
605 605 speed_t ospeed;
606 606 if (termios_p->c_cflag & CBAUDEXT)
607 607 ospeed = (termios_p->c_cflag & CBAUD) + CBAUD + 1;
608 608 else
609 609 ospeed = termios_p->c_cflag & CBAUD;
610 610
611 611 To store the output speed in the termios structure pointed to by
612 612 termios_p see the following code segment.
613 613
614 614 speed_t ospeed;
615 615 if (ospeed > CBAUD) {
616 616 termios_p->c_cflag |= CBAUDEXT;
617 617 ospeed -= (CBAUD + 1);
618 618 } else {
619 619 termios_p->c_cflag &= ~CBAUDEXT;
620 620 }
621 621 termios_p->c_cflag =
622 622 (termios_p->c_cflag & ~CBAUD) | (ospeed & CBAUD);
623 623
624 624 The zero baud rate, B0, is used to hang up the connection. If B0 is
625 625 specified, the data-terminal-ready signal is not asserted. Normally,
626 626 this disconnects the line.
627 627
628 628 If the CIBAUDEXT or CIBAUD bits are not zero, they specify the input baud
629 629 rate, with the CBAUDEXT and CBAUD bits specifying the output baud rate;
630 630 otherwise, the output and input baud rates are both specified by the
631 631 CBAUDEXT and CBAUD bits. The values for the CIBAUD bits are the same as
632 632 the values for the CBAUD bits, shifted left IBSHIFT bits. For any
633 633 particular hardware, impossible speed changes are ignored. To retrieve
634 634 the input speed in the termios structure pointed to by termios_p see the
635 635 following code segment.
636 636
637 637 speed_t ispeed;
638 638 if (termios_p->c_cflag & CIBAUDEXT) {
639 639 ispeed = ((termios_p->c_cflag & CIBAUD) >> IBSHIFT)
640 640 + (CIBAUD >> IBSHIFT) + 1;
641 641 } else {
642 642 ispeed = (termios_p->c_cflag & CIBAUD) >> IBSHIFT;
643 643 }
644 644
645 645 To store the input speed in the termios structure pointed to by termios_p
646 646 see the following code segment.
647 647
648 648 speed_t ispeed;
649 649 if (ispeed == 0) {
650 650 ispeed = termios_p->c_cflag & CBAUD;
651 651 if (termios_p->c_cflag & CBAUDEXT)
652 652 ispeed += (CBAUD + 1);
653 653 }
654 654 if ((ispeed << IBSHIFT) > CIBAUD) {
655 655 termios_p->c_cflag |= CIBAUDEXT;
656 656 ispeed -= ((CIBAUD >> IBSHIFT) + 1);
657 657 } else {
658 658 termios_p->c_cflag &= ~CIBAUDEXT;
659 659 }
660 660 termios_p->c_cflag =
661 661 (termios_p->c_cflag & ~CIBAUD) | ((ispeed << IBSHIFT) & CIBAUD);
662 662
663 663 The CSIZE bits specify the character size in bits for both transmission
664 664 and reception. This size does not include the parity bit, if any. If
665 665 CSTOPB is set, two stop bits are used; otherwise, one stop bit is used.
666 666 For example, at 110 baud, two stops bits are required.
667 667
668 668 If PARENB is set, parity generation and detection is enabled, and a
669 669 parity bit is added to each character. If parity is enabled, the PARODD
670 670 flag specifies odd parity if set; otherwise, even parity is used.
671 671
672 672 If CREAD is set, the receiver is enabled. Otherwise, no characters are
673 673 received.
674 674
675 675 If HUPCL is set, the line is disconnected when the last process with the
676 676 line open closes it or terminates. That is, the data-terminal-ready
677 677 signal is not asserted.
678 678
679 679 If CLOCAL is set, the line is assumed to be a local, direct connection
680 680 with no modem control; otherwise, modem control is assumed.
681 681
682 682 If CRTSXOFF is set, inbound hardware flow control is enabled.
683 683
684 684 If CRTSCTS is set, outbound hardware flow control is enabled.
685 685
686 686 The four possible combinations for the state of CRTSCTS and CRTSXOFF bits
687 687 and their interactions are described below.
688 688
689 689 Case A: CRTSCTS off, CRTSXOFF off. In this case the hardware flow
690 690 control is disabled.
691 691
692 692 Case B: CRTSCTS on, CRTSXOFF off. In this case only outbound hardware
693 693 flow control is enabled. The state of CTS signal is used to do
694 694 outbound flow control. It is expected that output will be
695 695 suspended if CTS is low and resumed when CTS is high.
696 696
697 697 Case C: CRTSCTS off, CRTSXOFF on. In this case only inbound hardware
698 698 flow control is enabled. The state of RTS signal is used to do
699 699 inbound flow control. It is expected that input will be
700 700 suspended if RTS is low and resumed when RTS is high.
701 701
702 702 Case D: CRTSCTS on, CRTSXOFF on. In this case both inbound and outbound
703 703 hardware flow control are enabled. Uses the state of CTS signal
704 704 to do outbound flow control and RTS signal to do inbound flow
705 705 control.
706 706
707 707 Local Modes
708 708 The c_lflag field of the argument structure is used by the line
709 709 discipline to control terminal functions. The basic line discipline
710 710 provides the following:
711 711
712 712 ISIG Enable signals.
713 713 ICANON Canonical input (erase and kill processing).
714 714 XCASE Canonical upper/lower presentation.
715 715 ECHO Enable echo.
716 716 ECHOE Echo erase character as BS-SP-BS &.
717 717 ECHOK Echo NL after kill character.
718 718 ECHONL Echo NL.
719 719 NOFLSH Disable flush after interrupt or quit.
720 720 TOSTOP Send
721 721 SIGTTOU for background output.
722 722 ECHOCTL Echo control characters as char, delete as ^?.
723 723 ECHOPRT Echo erase character as character erased.
724 724 ECHOKE BS-SP-BS erase entire line on line kill.
725 725 FLUSHO Output is being flushed.
726 726 PENDIN Retype pending input at next read or input character.
727 727 IEXTEN Enable extended (implementation-defined) functions.
728 728
729 729 If ISIG is set, each input character is checked against the special
730 730 control characters INTR, QUIT, SWTCH, SUSP, STATUS, and DSUSP. If an
731 731 input character matches one of these control characters, the function
732 732 associated with that character is performed. (Note: If SWTCH is set and
733 733 the character matches, the character is simply discarded. No other
734 734 action is taken.) If ISIG is not set, no checking is done. Thus, these
735 735 special input functions are possible only if ISIG is set.
736 736
737 737 If ICANON is set, canonical processing is enabled. This enables the
738 738 erase and kill edit functions, and the assembly of input characters into
739 739 lines delimited by NL-c, EOF, EOL, and EOL. If ICANON is not set, read
740 740 requests are satisfied directly from the input queue. A read is not
741 741 satisfied until at least MIN characters have been received or the timeout
742 742 value TIME has expired between characters. This allows fast bursts of
743 743 input to be read efficiently while still allowing single character input.
744 744 The time value represents tenths of seconds.
745 745
746 746 If XCASE is set and ICANON is set, an upper case letter is accepted on
747 747 input if preceded by a backslash `\' character, and is output preceded by
748 748 a backslash `\' character. In this mode, the following escape sequences
749 749 are generated on output and accepted on input:
750 750
751 751 FOR: USE:
752 752 ` \'
753 753 | \!
754 754 ~ \^
755 755 { \(
756 756 } \)
757 757 \ \\
758 758
759 759 For example, input A as \a, \n as \\n, and \N as \\\n.
760 760
761 761 If ECHO is set, characters are echoed as received.
762 762
763 763 When ICANON is set, the following echo functions are possible.
764 764
765 765 o If ECHO and ECHOE are set, and ECHOPRT is not set, the ERASE,
766 766 ERASE2, and WERASE characters are echoed as one or more ASCII
767 767 BS SP BS, which clears the last character(s) from a CRT screen.
768 768
769 769 o If ECHO, ECHOPRT, and IEXTEN are set, the first ERASE, ERASE2,
770 770 and WERASE character in a sequence echoes as a backslash `\',
771 771 followed by the characters being erased. Subsequent ERASE and
772 772 WERASE characters echo the characters being erased, in reverse
773 773 order. The next non-erase character causes a `/' (slash) to be
774 774 typed before it is echoed. ECHOPRT should be used for hard
775 775 copy terminals.
776 776
777 777 o If ECHOKE and IEXTEN are set, the kill character is echoed by
778 778 erasing each character on the line from the screen (using the
779 779 mechanism selected by ECHOE and ECHOPR).
780 780
781 781 o If ECHOK is set, and ECHOKE is not set, the NL character is
782 782 echoed after the kill character to emphasize that the line is
783 783 deleted. Note that a `\' (escape) character or an LNEXT
784 784 character preceding the erase or kill character removes any
785 785 special function.
786 786
787 787 o If ECHONL is set, the NL character is echoed even if ECHO is
788 788 not set. This is useful for terminals set to local echo (so
789 789 called half-duplex).
790 790
791 791 If ECHOCTL and IEXTEN are set, all control characters (characters with
792 792 codes between 0 and 37 octal) other than ASCII TAB, ASCII NL, the START
793 793 character, and the STOP character, ASCII CR, and ASCII BS are echoed as
794 794 ^X, where X is the character given by adding `100' octal to the code of
795 795 the control character (so that the character with octal code `1' is
796 796 echoed as ^A), and the ASCII DEL character, with code `177' octal, is
797 797 echoed as ^?.
798 798
799 799 If NOFLSH is set, the normal flush of the input and output queues
800 800 associated with the INTR, QUIT, STATUS, and SUSP characters is not done.
801 801 This bit should be set when restarting system calls that read from or
802 802 write to a terminal (see sigaction(2)).
803 803
804 804 If TOSTOP and IEXTEN are set, the signal SIGTTOU is sent to a process
805 805 that tries to write to its controlling terminal if it is not in the
806 806 foreground process group for that terminal. This signal normally stops
807 807 the process. Otherwise, the output generated by that process is output
808 808 to the current output stream. Processes that are blocking or ignoring
809 809 SIGTTOU signals are excepted and allowed to produce output, if any.
810 810
811 811 If FLUSHO and IEXTEN are set, data written to the terminal is discarded.
812 812 This bit is set when the FLUSH character is typed. A program can cancel
813 813 the effect of typing the FLUSH character by clearing FLUSHO.
814 814
815 815 If PENDIN and IEXTEN are set, any input that has not yet been read is
816 816 reprinted when the next character arrives as input. PENDIN is then
817 817 automatically cleared.
818 818
819 819 If IEXTEN is set, the following implementation-defined functions are
820 820 enabled: special characters ( WERASE, REPRINT, DISCARD, and LNEXT) and
821 821 local flags ( TOSTOP, ECHOCTL, ECHOPRT, ECHOKE, FLUSHO, and PENDIN).
822 822
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823 823 Minimum and Timeout
824 824 The MIN and TIME values were described previously, in the subsection,
825 825 Non-canonical Mode Input Processing. The initial value of MIN is 1, and
826 826 the initial value of TIME is 0.
827 827
828 828 Terminal Size
829 829 The number of lines and columns on the terminal's display is specified in
830 830 the winsize structure defined by <sys/termios.h> and includes the
831 831 following members:
832 832
833 - unsigned short ws_row; /* rows, in characters */
833 + unsigned short ws_row; /* rows, in characters */
834 834 unsigned short ws_col; /* columns, in characters */
835 835 unsigned short ws_xpixel; /* horizontal size, in pixels */
836 836 unsigned short ws_ypixel; /* vertical size, in pixels */
837 837
838 838 Termio Structure
839 839 The SunOS/SVR4 termio structure is used by some ioctl()s; it is defined
840 840 by <sys/termio.h> and includes the following members:
841 841
842 842 unsigned short c_iflag; /* input modes */
843 843 unsigned short c_oflag; /* output modes */
844 844 unsigned short c_cflag; /* control modes */
845 845 unsigned short c_lflag; /* local modes */
846 846 char c_line; /* line discipline */
847 847 unsigned char c_cc[NCC]; /* control chars */
848 848
849 849 The special control characters are defined by the array c_cc. The
850 850 symbolic name NCC is the size of the Control-character array and is also
851 851 defined by <termio.h>. The relative positions, subscript names, and
852 852 typical default values for each function are as follows:
853 853
854 854 Relative Positions Subscript Names Typical Default Values
855 855 0 VINTR EXT
856 856 1 VQUIT FS
857 857 2 VERASE DEL
858 858 3 VKILL NAK
859 859 4 VEOF EOT
860 860 5 VEOL NUL
861 861 6 VEOL2 NUL
862 862 7 Reserved
863 863
864 864 The MIN values is stored in the VMIN element of the c_cc array; the TIME
865 865 value is stored in the VTIME element of the c_cc array. The VMIN element
866 866 is the same element as the VEOF element; the VTIME element is the same
867 867 element as the VEOL element.
868 868
869 869 The calls that use the termio structure only affect the flags and control
870 870 characters that can be stored in the termio structure; all other flags
871 871 and control characters are unaffected.
872 872
873 873 Modem Lines
874 874 On special files representing serial ports, modem control lines can be
875 875 read. Control lines (if the underlying hardware supports it) may also be
876 876 changed. Status lines are read-only. The following modem control and
877 877 status lines may be supported by a device; they are defined by
878 878 <sys/termios.h>:
879 879
880 880 TIOCM_LE line enable
881 881 TIOCM_DTR data terminal ready
882 882 TIOCM_RTS request to send
883 883 TIOCM_ST secondary transmit
884 884 TIOCM_SR secondary receive
885 885 TIOCM_CTS clear to send
886 886 TIOCM_CAR carrier detect
887 887 TIOCM_RNG ring
888 888 TIOCM_DSR data set ready
889 889
890 890 TIOCM_CD is a synonym for TIOCM_CAR, and TIOCM_RI is a synonym for
891 891 TIOCM_RNG. Not all of these are necessarily supported by any particular
892 892 device; check the manual page for the device in question.
893 893
894 894 The software carrier mode can be enabled or disabled using the
895 895 TIOCSSOFTCAR ioctl(). If the software carrier flag for a line is off,
896 896 the line pays attention to the hardware carrier detect (DCD) signal. The
897 897 tty device associated with the line cannot be opened until DCD is
898 898 asserted. If the software carrier flag is on, the line behaves as if DCD
899 899 is always asserted.
900 900
901 901 The software carrier flag is usually turned on for locally connected
902 902 terminals or other devices, and is off for lines with modems.
903 903
904 904 To be able to issue the TIOCGSOFTCAR and TIOCSSOFTCAR ioctl() calls, the
905 905 tty line should be opened with O_NDELAY so that the open(2) will not wait
906 906 for the carrier.
907 907
908 908 Default Values
909 909 The initial termios values upon driver open is configurable. This is
910 910 accomplished by setting the "ttymodes" property in the file
911 911 /kernel/drv/options.conf. Since this property is assigned during system
912 912 initialization, any change to the "ttymodes" property will not take
913 913 effect until the next reboot. The string value assigned to this property
914 914 should be in the same format as the output of the stty(1) command with
915 915 the -g option.
916 916
917 917 If this property is undefined, the following termios modes are in effect.
918 918 The initial input control value is BRKINT, ICRNL, IXON, IMAXBEL. The
919 919 initial output control value is OPOST, ONLCR, TAB3. The initial hardware
920 920 control value is B9600, CS8, CREAD. The initial line-discipline control
921 921 value is ISIG, ICANON, IEXTEN, ECHO, ECHOK, ECHOE, ECHOKE, ECHOCTL.
922 922
923 923 IOCTLS
924 924 The ioctl()s supported by devices and STREAMS modules providing the
925 925 termios(3C) interface are listed below. Some calls may not be supported
926 926 by all devices or modules. The functionality provided by these calls is
927 927 also available through the preferred function call interface specified on
928 928 termios.
929 929
930 930 TCGETS The argument is a pointer to a termios structure. The
931 931 current terminal parameters are fetched and stored into
932 932 that structure.
933 933
934 934 TCSETS The argument is a pointer to a termios structure. The
935 935 current terminal parameters are set from the values stored
936 936 in that structure. The change is immediate.
937 937
938 938 TCSETSW The argument is a pointer to a termios structure. The
939 939 current terminal parameters are set from the values stored
940 940 in that structure. The change occurs after all characters
941 941 queued for output have been transmitted. This form should
942 942 be used when changing parameters that affect output.
943 943
944 944 TCSETSF The argument is a pointer to a termios structure. The
945 945 current terminal parameters are set from the values stored
946 946 in that structure. The change occurs after all characters
947 947 queued for output have been transmitted; all characters
948 948 queued for input are discarded and then the change occurs.
949 949
950 950 TCGETA The argument is a pointer to a termio structure. The
951 951 current terminal parameters are fetched, and those
952 952 parameters that can be stored in a termio structure are
953 953 stored into that structure.
954 954
955 955 TCSETA The argument is a pointer to a termio structure. Those
956 956 terminal parameters that can be stored in a termio
957 957 structure are set from the values stored in that structure.
958 958 The change is immediate.
959 959
960 960 TCSETAW The argument is a pointer to a termio structure. Those
961 961 terminal parameters that can be stored in a termio
962 962 structure are set from the values stored in that structure.
963 963 The change occurs after all characters queued for output
964 964 have been transmitted. This form should be used when
965 965 changing parameters that affect output.
966 966
967 967 TCSETAF The argument is a pointer to a termio structure. Those
968 968 terminal parameters that can be stored in a termio
969 969 structure are set from the values stored in that structure.
970 970 The change occurs after all characters queued for output
971 971 have been transmitted; all characters queued for input are
972 972 discarded and then the change occurs.
973 973
974 974 TCSBRK The argument is an int value. Wait for the output to
975 975 drain. If the argument is 0, then send a break (zero
976 976 valued bits for 0.25 seconds).
977 977
978 978 TCXONC Start/stop control. The argument is an int value. If the
979 979 argument is 0, suspend output; if 1, restart suspended
980 980 output; if 2, suspend input; if 3, restart suspended input.
981 981
982 982 TCFLSH The argument is an int value. If the argument is 0, flush
983 983 the input queue; if 1, flush the output queue; if 2, flush
984 984 both the input and output queues.
985 985
986 986 TIOCGPGRP The argument is a pointer to a pid_t. Set the value of
987 987 that pid_t to the process group ID of the foreground
988 988 process group associated with the terminal. See
989 989 termios(3C) for a description of TCGETPGRP.
990 990
991 991 TIOCSPGRP The argument is a pointer to a pid_t. Associate the
992 992 process group whose process group ID is specified by the
993 993 value of that pid_t with the terminal. The new process
994 994 group value must be in the range of valid process group ID
995 995 values. Otherwise, the error EPERM is returned.
996 996
997 997 TIOCGSID The argument is a pointer to a pid_t. The session ID of
998 998 the terminal is fetched and stored in the pid_t.
999 999
1000 1000 TIOCGWINSZ The argument is a pointer to a winsize structure. The
1001 1001 terminal driver's notion of the terminal size is stored
1002 1002 into that structure.
1003 1003
1004 1004 TIOCSWINSZ The argument is a pointer to a winsize structure. The
1005 1005 terminal driver's notion of the terminal size is set from
1006 1006 the values specified in that structure. If the new sizes
1007 1007 are different from the old sizes, a SIGWINCH signal is set
1008 1008 to the process group of the terminal.
1009 1009
1010 1010 TIOCMBIS The argument is a pointer to an int whose value is a mask
1011 1011 containing modem control lines to be turned on. The
1012 1012 control lines whose bits are set in the argument are turned
1013 1013 on; no other control lines are affected.
1014 1014
1015 1015 TIOCMBIC The argument is a pointer to an int whose value is a mask
1016 1016 containing modem control lines to be turned off. The
1017 1017 control lines whose bits are set in the argument are turned
1018 1018 off; no other control lines are affected.
1019 1019
1020 1020 TIOCMGET The argument is a pointer to an int. The current state of
1021 1021 the modem status lines is fetched and stored in the int
1022 1022 pointed to by the argument.
1023 1023
1024 1024 TIOCMSET The argument is a pointer to an int containing a new set of
1025 1025 modem control lines. The modem control lines are turned on
1026 1026 or off, depending on whether the bit for that mode is set
1027 1027 or clear.
1028 1028
1029 1029 TIOCSPPS The argument is a pointer to an int that determines whether
1030 1030 pulse-per-second event handling is to be enabled (non-zero)
1031 1031 or disabled (zero). If a one-pulse-per-second reference
1032 1032 clock is attached to the serial line's data carrier detect
1033 1033 input, the local system clock will be calibrated to it. A
1034 1034 clock with a high error, that is, a deviation of more than
1035 1035 25 microseconds per tick, is ignored.
1036 1036
1037 1037 TIOCGPPS The argument is a pointer to an int, in which the state of
1038 1038 the even handling is returned. The int is set to a non-
1039 1039 zero value if pulse-per-second (PPS) handling has been
1040 1040 enabled. Otherwise, it is set to zero.
1041 1041
1042 1042 TIOCGSOFTCAR The argument is a pointer to an int whose value is 1 or 0,
1043 1043 depending on whether the software carrier detect is turned
1044 1044 on or off.
1045 1045
1046 1046 TIOCSSOFTCAR The argument is a pointer to an int whose value is 1 or 0.
1047 1047 The value of the integer should be 0 to turn off software
1048 1048 carrier, or 1 to turn it on.
1049 1049
1050 1050 TIOCGPPSEV The argument is a pointer to a struct ppsclockev. This
1051 1051 structure contains the following members:
1052 1052
1053 1053 struct timeval tv;
1054 1054 uint32_t serial;
1055 1055
1056 1056 tv is the system clock timestamp when the event (pulse on
1057 1057 the DCD pin) occurred. serial is the ordinal of the event,
1058 1058 which each consecutive event being assigned the next
1059 1059 ordinal. The first event registered gets a serial value of
1060 1060 1. The TIOCGPPSEV returns the last event registered;
1061 1061 multiple calls will persistently return the same event
1062 1062 until a new one is registered. In addition to time
1063 1063 stamping and saving the event, if it is of one-second
1064 1064 period and of consistently high accuracy, the local system
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1065 1065 clock will automatically calibrate to it.
1066 1066
1067 1067 FILES
1068 1068 Files in or under /dev
1069 1069
1070 1070 SEE ALSO
1071 1071 stty(1), fork(2), getpgid(2), getsid(2), ioctl(2), setsid(2),
1072 1072 sigaction(2), signal(3C), tcsetpgrp(3C), termios(3C), signal.h(3HEAD),
1073 1073 streamio(7I)
1074 1074
1075 -illumos March 17, 2019 illumos
1075 +illumos February 17, 2020 illumos
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