1 .\" Copyright (c) 1991, 1992, 1993
2 .\" The Regents of the University of California. All rights reserved.
4 .\" Redistribution and use in source and binary forms, with or without
5 .\" modification, are permitted provided that the following conditions
7 .\" 1. Redistributions of source code must retain the above copyright
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14 .\" This product includes software developed by the University of
15 .\" California, Berkeley and its contributors.
16 .\" 4. Neither the name of the University nor the names of its contributors
17 .\" may be used to endorse or promote products derived from this software
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20 .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 .\" @(#)termios.4 8.4 (Berkeley) 4/19/94
33 .\" $FreeBSD: src/share/man/man4/termios.4,v 1.12.2.9 2001/12/17 11:30:12 ru Exp $
40 .Nd general terminal line discipline
44 This describes a general terminal line discipline that is
45 supported on tty asynchronous communication ports.
46 .Ss Opening a Terminal Device File
47 When a terminal file is opened, it normally causes the process to wait
48 until a connection is established. For most hardware, the presence
49 of a connection is indicated by the assertion of the hardware
52 If the termios structure associated with the terminal file has the
54 flag set in the cflag, or if the
59 call, then the open will succeed even without
60 a connection being present.
61 In practice, applications
62 seldom open these files; they are opened by special programs, such
68 an application's standard input, output, and error files.
69 .Ss Job Control in a Nutshell
70 Every process is associated with a particular process group and session.
71 The grouping is hierarchical: every member of a particular process group is a
72 member of the same session. This structuring is used in managing groups
73 of related processes for purposes of
74 .\" .Gw "job control" ;
77 ability from the keyboard (or from program control) to simultaneously
79 a complex command (a command composed of one or more related
80 processes). The grouping into process groups allows delivering
81 of signals that stop or start the group as a whole, along with
82 arbitrating which process group has access to the single controlling
83 terminal. The grouping at a higher layer into sessions is to restrict
84 the job control related signals and system calls to within processes
85 resulting from a particular instance of a "login". Typically, a session
86 is created when a user logs in, and the login terminal is setup
87 to be the controlling terminal; all processes spawned from that
88 login shell are in the same session, and inherit the controlling
92 operating interactively (that is, reading commands from a terminal)
93 normally groups related processes together by placing them into the
94 same process group. A set of processes in the same process group
95 is collectively referred to as a "job". When the foreground process
96 group of the terminal is the same as the process group of a particular
97 job, that job is said to be in the "foreground". When the process
98 group of the terminal is different from the process group of
99 a job (but is still the controlling terminal), that job is said
100 to be in the "background". Normally the
101 shell reads a command and starts the job that implements that
102 command. If the command is to be started in the foreground (typical), it
103 sets the process group of the terminal to the process group
104 of the started job, waits for the job to complete, and then
105 sets the process group of the terminal back to its own process
106 group (it puts itself into the foreground). If the job is to
107 be started in the background (as denoted by the shell operator "&"),
108 it never changes the process group of the terminal and doesn't
109 wait for the job to complete (that is, it immediately attempts to read the next
110 command). If the job is started in the foreground, the user may
113 which generates the terminal stop signal
115 and has the effect of stopping the entire job.
116 The shell will notice that the job stopped, and will resume running after
117 placing itself in the foreground.
118 The shell also has commands for placing stopped jobs in the background,
119 and for placing stopped or background jobs into the foreground.
120 .Ss Orphaned Process Groups
121 An orphaned process group is a process group that has no process
122 whose parent is in a different process group, yet is in the same
123 session. Conceptually it means a process group that doesn't have
124 a parent that could do anything if it were to be stopped. For example,
125 the initial login shell is typically in an orphaned process group.
126 Orphaned process groups are immune to keyboard generated stop
127 signals and job control signals resulting from reads or writes to the
128 controlling terminal.
129 .Ss The Controlling Terminal
130 A terminal may belong to a process as its controlling terminal. Each
131 process of a session that has a controlling terminal has the same
132 controlling terminal. A terminal may be the controlling terminal for at
133 most one session. The controlling terminal for a session is allocated by
134 the session leader by issuing the
136 ioctl. A controlling terminal
137 is never acquired by merely opening a terminal device file.
138 When a controlling terminal becomes
139 associated with a session, its foreground process group is set to
140 the process group of the session leader.
142 The controlling terminal is inherited by a child process during a
144 function call. A process relinquishes its controlling terminal when it
145 creates a new session with the
147 function; other processes
148 remaining in the old session that had this terminal as their controlling
149 terminal continue to have it.
150 A process does not relinquish its
151 controlling terminal simply by closing all of its file descriptors
152 associated with the controlling terminal if other processes continue to
155 When a controlling process terminates, the controlling terminal is
156 disassociated from the current session, allowing it to be acquired by a
157 new session leader. Subsequent access to the terminal by other processes
158 in the earlier session will be denied, with attempts to access the
159 terminal treated as if modem disconnect had been sensed.
160 .Ss Terminal Access Control
161 If a process is in the foreground process group of its controlling
162 terminal, read operations are allowed.
163 Any attempts by a process
164 in a background process group to read from its controlling terminal
170 following special cases apply: If the reading process is ignoring or
173 signal, or if the process group of the reading
174 process is orphaned, the
180 signal is sent. The default action of the
182 signal is to stop the
183 process to which it is sent.
185 If a process is in the foreground process group of its controlling
186 terminal, write operations are allowed.
187 Attempts by a process in a background process group to write to its
188 controlling terminal will cause the process group to be sent a
190 signal unless one of the following special cases apply: If
195 is set and the process is ignoring or blocking the
197 signal, the process is allowed to write to the terminal and the
199 signal is not sent. If
201 is set, and the process group of
202 the writing process is orphaned, and the writing process is not ignoring
210 and no signal is sent.
212 Certain calls that set terminal parameters are treated in the same
213 fashion as write, except that
215 is ignored; that is, the effect is
216 identical to that of terminal writes when
219 .Ss Input Processing and Reading Data
220 A terminal device associated with a terminal device file may operate in
221 full-duplex mode, so that data may arrive even while output is occurring.
222 Each terminal device file has associated with it an input queue, into
223 which incoming data is stored by the system before being read by a
224 process. The system imposes a limit,
225 .Pf \&{ Dv MAX_INPUT Ns \&} ,
227 bytes that may be stored in the input queue. The behavior of the system
228 when this limit is exceeded depends on the setting of the
232 If this flag is set, the terminal
236 character each time a character is received
237 while the input queue is full. Otherwise, the input queue is flushed
238 upon receiving the character.
240 Two general kinds of input processing are available, determined by
241 whether the terminal device file is in canonical mode or noncanonical
244 input characters are processed according to the
248 fields. Such processing can include echoing, which
249 in general means transmitting input characters immediately back to the
250 terminal when they are received from the terminal. This is useful for
251 terminals that can operate in full-duplex mode.
253 The manner in which data is provided to a process reading from a terminal
254 device file is dependent on whether the terminal device file is in
255 canonical or noncanonical mode.
257 Another dependency is whether the
265 flag is clear, then the read request is
266 blocked until data is available or a signal has been received. If the
268 flag is set, then the read request is completed, without
269 blocking, in one of three ways:
270 .Bl -enum -offset indent
272 If there is enough data available to satisfy the entire request,
273 and the read completes successfully the number of
274 bytes read is returned.
276 If there is not enough data available to satisfy the entire
277 request, and the read completes successfully, having read as
278 much data as possible, the number of bytes read is returned.
280 If there is no data available, the read returns -1, with
285 When data is available depends on whether the input processing mode is
286 canonical or noncanonical.
287 .Ss Canonical Mode Input Processing
288 In canonical mode input processing, terminal input is processed in units
289 of lines. A line is delimited by a newline
291 character, an end-of-file
293 character, or an end-of-line
296 .Sx "Special Characters"
302 This means that a read request will
303 not return until an entire line has been typed, or a signal has been
304 received. Also, no matter how many bytes are requested in the read call,
305 at most one line is returned. It is not, however, necessary to
306 read a whole line at once; any number of bytes, even one, may be
307 requested in a read without losing information.
309 .Pf \&{ Dv MAX_CANON Ns \&}
311 number of bytes in a line.
312 The behavior of the system when this limit is
313 exceeded is the same as when the input queue limit
314 .Pf \&{ Dv MAX_INPUT Ns \&} ,
317 Erase and kill processing occur when either of two special characters,
323 .Sx "Special Characters section" ) ,
325 This processing affects data in the input queue that has not yet been
326 delimited by a newline
331 character. This un-delimited
332 data makes up the current line. The
334 character deletes the last
335 character in the current line, if there is any. The
338 deletes all data in the current line, if there is any. The
342 characters have no effect if there is no data in the current line.
347 characters themselves are not placed in the input
349 .Ss Noncanonical Mode Input Processing
350 In noncanonical mode input processing, input bytes are not assembled into
351 lines, and erase and kill processing does not occur. The values of the
357 array are used to determine how to
358 process the bytes received.
361 represents the minimum number of bytes that should be received when
364 function successfully returns.
366 is a timer of 0.1 second
367 granularity that is used to time out bursty and short term data
371 .Dv \&{ Dv MAX_INPUT Ns \&} ,
373 request is undefined. The four possible values for
378 their interactions are described below.
379 .Ss "Case A: MIN > 0, TIME > 0"
382 serves as an inter-byte timer and is activated after
383 the first byte is received. Since it is an inter-byte timer, it is reset
384 after a byte is received. The interaction between
389 follows: as soon as one byte is received, the inter-byte timer is
392 bytes are received before the inter-byte timer expires
393 (remember that the timer is reset upon receipt of each byte), the read is
394 satisfied. If the timer expires before
396 bytes are received, the
397 characters received to that point are returned to the user. Note that if
399 expires at least one byte is returned because the timer would
400 not have been enabled unless a byte was received. In this case
404 > 0) the read blocks until the
409 activated by the receipt of the first byte, or a signal is received. If
410 data is in the buffer at the time of the
413 if data had been received immediately after the
415 .Ss "Case B: MIN > 0, TIME = 0"
416 In this case, since the value of
418 is zero, the timer plays no role
421 is significant. A pending read is not satisfied until
423 bytes are received (i.e., the pending read blocks until
426 are received), or a signal is received. A program that uses this case to
427 read record-based terminal
429 may block indefinitely in the read
431 .Ss "Case C: MIN = 0, TIME > 0"
436 no longer represents an inter-byte
437 timer. It now serves as a read timer that is activated as soon as the
438 read function is processed. A read is satisfied as soon as a single
439 byte is received or the read timer expires. Note that in this case if
440 the timer expires, no bytes are returned. If the timer does not
441 expire, the only way the read can be satisfied is if a byte is received.
442 In this case the read will not block indefinitely waiting for a byte; if
443 no byte is received within
445 seconds after the read is initiated,
446 the read returns a value of zero, having read no data. If data is
447 in the buffer at the time of the read, the timer is started as if
448 data had been received immediately after the read.
449 .Ss Case D: MIN = 0, TIME = 0
450 The minimum of either the number of bytes requested or the number of
451 bytes currently available is returned without waiting for more
452 bytes to be input. If no characters are available, read returns a
453 value of zero, having read no data.
454 .Ss Writing Data and Output Processing
455 When a process writes one or more bytes to a terminal device file, they
456 are processed according to the
461 implementation may provide a buffering mechanism; as such, when a call to
463 completes, all of the bytes written have been scheduled for
464 transmission to the device, but the transmission will not necessarily
466 .\" See also .Sx "6.4.2" for the effects of
469 .Ss Special Characters
470 Certain characters have special functions on input or output or both.
471 These functions are summarized as follows:
472 .Bl -tag -width indent
474 Special character on input and is recognized if the
478 section) is enabled. Generates a
480 signal which is sent to all processes in the foreground
481 process group for which the terminal is the controlling
487 discarded when processed.
489 Special character on input and is recognized if the
491 flag is enabled. Generates a
494 sent to all processes in the foreground process group
495 for which the terminal is the controlling terminal. If
499 character is discarded when
502 Special character on input and is recognized if the
504 flag is set. Erases the last character in the
506 .Sx "Canonical Mode Input Processing" .
507 It does not erase beyond
508 the start of a line, as delimited by an
518 discarded when processed.
520 Special character on input and is recognized if the
522 flag is set. Deletes the entire line, as
532 character is discarded when processed.
534 Special character on input and is recognized if the
536 flag is set. When received, all the bytes
537 waiting to be read are immediately passed to the
538 process, without waiting for a newline, and the
540 is discarded. Thus, if there are no bytes waiting (that
543 occurred at the beginning of a line), a byte
544 count of zero is returned from the
546 representing an end-of-file indication. If
551 character is discarded when processed.
553 Special character on input and is recognized if the
555 flag is set. It is the line delimiter
558 Special character on input and is recognized if the
560 flag is set. Is an additional line delimiter,
566 flag is enabled, receipt of the
570 signal to be sent to all processes in the
571 foreground process group for which the terminal is the
572 controlling terminal, and the
575 discarded when processed.
577 Special character on both input and output and is
583 control) flag is set. Can be used to temporarily
584 suspend output. It is useful with fast terminals to
585 prevent output from disappearing before it can be read.
590 character is discarded when
593 Special character on both input and output and is
599 control) flag is set. Can be used to resume output that
600 has been suspended by a
606 character is discarded when processed.
608 Special character on input and is recognized if the
610 flag is set; it is the
620 is not set, this character is translated into a
623 has the same effect as a
628 The following special characters are extensions defined by this
629 system and are not a part of
632 .Bl -tag -width indent
636 character. Same function as
639 Special character on input and is recognized if the
641 flag is set. Erases the last word in the current
642 line according to one of two algorithms. If the
644 flag is not set, first any preceding whitespace is
645 erased, and then the maximal sequence of non-whitespace
648 is set, first any preceding
649 whitespace is erased, and then the maximal sequence
650 of alphabetic/underscores or non alphabetic/underscores.
651 As a special case in this second algorithm, the first previous
652 non-whitespace character is skipped in determining
653 whether the preceding word is a sequence of
654 alphabetic/underscores. This sounds confusing but turns
655 out to be quite practical.
657 Special character on input and is recognized if the
659 flag is set. Causes the current input edit line
662 Has similar actions to the
664 character, except that
667 signal is delivered when one of the processes
668 in the foreground process group issues a
671 controlling terminal.
673 Special character on input and is recognized if the
675 flag is set. Receipt of this character causes the next
676 character to be taken literally.
678 Special character on input and is recognized if the
680 flag is set. Receipt of this character toggles the flushing
683 Special character on input and is recognized if the
685 flag is set. Receipt of this character causes a
687 signal to be sent to the foreground process group of the
688 terminal. Also, if the
691 causes the kernel to write a status message to the terminal
692 that displays the current load average, the name of the
693 command in the foreground, its process ID, the symbolic
694 wait channel, the number of user and system seconds used,
695 the percentage of cpu the process is getting, and the resident
696 set size of the process.
703 characters cannot be changed.
704 The values for all the remaining characters can be set and are
705 described later in the document under
706 Special Control Characters.
709 character functions associated with changeable special control characters
710 can be disabled individually by setting their value to
711 .Dv {_POSIX_VDISABLE} ;
713 .Sx "Special Control Characters" .
715 If two or more special characters have the same value, the function
716 performed when that character is received is undefined.
718 If a modem disconnect is detected by the terminal interface for a
719 controlling terminal, and if
726 signal is sent to the controlling
727 process associated with the terminal. Unless other arrangements have
728 been made, this causes the controlling process to terminate.
729 Any subsequent call to the
731 function returns the value zero,
732 indicating end of file. Thus, processes that read a terminal
733 file and test for end-of-file can terminate appropriately after a
737 .\" condition specified in 6.1.1.4 that applies
738 .\" when the implementation supports job control also exists, it is
739 .\" unspecified whether the
747 to the terminal device returns -1, with
751 until the device is closed.
752 .Sh General Terminal Interface
753 .Ss Closing a Terminal Device File
754 The last process to close a terminal device file causes any output
755 to be sent to the device and any input to be discarded. Then, if
757 is set in the control modes, and the communications port supports a
758 disconnect function, the terminal device performs a disconnect.
759 .Ss Parameters That Can Be Set
760 Routines that need to control certain terminal
763 do so by using the termios structure as defined in the header
765 This structure contains minimally four scalar elements of bit flags
766 and one array of special characters. The scalar flag elements are
773 The character array is named
775 and its maximum index is
780 field describe the basic
781 terminal input control, and are composed of
784 .Bl -tag -width IMAXBEL -offset indent -compact
786 /* ignore BREAK condition */
788 /* map BREAK to SIGINTR */
790 /* ignore (discard) parity errors */
792 /* mark parity and framing errors */
794 /* enable checking of parity errors */
796 /* strip 8th bit off chars */
802 /* map CR to NL (ala CRMOD) */
804 /* enable output flow control */
806 /* enable input flow control */
808 /* any char will restart after stop */
810 /* ring bell on input queue full */
813 In the context of asynchronous serial data transmission, a break
814 condition is defined as a sequence of zero-valued bits that continues for
815 more than the time to send one byte. The entire sequence of zero-valued
816 bits is interpreted as a single break condition, even if it continues for
817 a time equivalent to more than one byte. In contexts other than
818 asynchronous serial data transmission the definition of a break condition
819 is implementation defined.
823 is set, a break condition detected on input is ignored, that
824 is, not put on the input queue and therefore not read by any process. If
828 is set, the break condition flushes the
829 input and output queues and if the terminal is the controlling terminal
830 of a foreground process group, the break condition generates a
833 signal to that foreground process group. If neither
837 is set, a break condition is read as a single
848 is set, a byte with a framing or parity error (other than
855 is not set, a byte with a framing or parity
856 error (other than break) is given to the application as the
857 three-character sequence
864 flag preceding each sequence and X is the data of the character received
865 in error. To avoid ambiguity in this case, if
870 is given to the application as
878 is set, a framing or parity error (other than
879 break) is given to the application as a single character
884 is set, input parity checking is enabled. If
887 input parity checking is disabled, allowing output parity generation
888 without input parity errors. Note that whether input parity checking is
889 enabled or disabled is independent of whether parity detection is enabled
891 .Sx "Control Modes" ) .
892 If parity detection is enabled but input
893 parity checking is disabled, the hardware to which the terminal is
894 connected recognizes the parity bit, but the terminal special file
895 does not check whether this bit is set correctly or not.
899 is set, valid input bytes are first stripped to seven bits,
900 otherwise all eight bits are processed.
906 character is translated into a
912 character is ignored (not
926 is set, start/stop output control is enabled. A received
928 character suspends output and a received
934 is also set, then any character may
943 read, but merely perform flow control functions. When
954 is set, start/stop input control is enabled. The system shall
957 characters, which are intended to cause the
958 terminal device to stop transmitting data, as needed to prevent the input
959 queue from overflowing and causing the undefined behavior described in
960 .Sx "Input Processing and Reading Data" ,
961 and shall transmit one or more
963 characters, which are
964 intended to cause the terminal device to resume transmitting data, as
965 soon as the device can continue transmitting data without risk of
966 overflowing the input queue. The precise conditions under which
970 characters are transmitted are implementation defined.
974 is set and the input queue is full, subsequent input shall cause an
977 character to be transmitted to
980 The initial input control value after
982 is implementation defined.
986 field describe the basic terminal output control,
987 and are composed of the following masks:
989 .Bl -tag -width OXTABS -offset indent -compact
991 /* enable following output processing */
993 /* map NL to CR-NL (ala
999 /* expand tabs to spaces */
1006 /* do not transmit CRs on column 0 */
1008 /* on the termianl NL performs the CR function */
1013 is set, the remaining flag masks are interpreted as follows;
1014 otherwise characters are transmitted without change.
1018 is set, newlines are translated to carriage return, linefeeds.
1022 is set, carriage returns are translated to newlines.
1026 is set, tabs are expanded to the appropriate number of
1027 spaces (assuming 8 column tab stops).
1034 are discarded on output.
1038 is set, no CR character is transmitted when at column 0 (first position).
1042 is set, the NL character is assumed to do the carriage-return function;
1043 the column pointer will be set to 0.
1047 field describe the basic
1048 terminal hardware control, and are composed of the
1051 specified are supported by all hardware.
1053 .Bl -tag -width CRTSXIFLOW -offset indent -compact
1055 /* character size mask */
1057 /* 5 bits (pseudo) */
1065 /* send 2 stop bits */
1067 /* enable receiver */
1071 /* odd parity, else even */
1073 /* hang up on last close */
1075 /* ignore modem status lines */
1079 flow control of output */
1085 /* RTS flow control of input */
1087 /* flow control output via Carrier */
1092 bits specify the byte size in bits for both transmission and
1097 and compared with the
1104 This size does not include the parity bit, if any. If
1106 is set, two stop bits are used, otherwise one stop bit. For example, at
1107 110 baud, two stop bits are normally used.
1111 is set, the receiver is enabled. Otherwise, no character is
1113 Not all hardware supports this bit. In fact, this flag
1114 is pretty silly and if it were not part of the
1117 it would be omitted.
1121 is set, parity generation and detection are enabled and a parity
1122 bit is added to each character. If parity is enabled,
1125 odd parity if set, otherwise even parity is used.
1129 is set, the modem control lines for the port are lowered
1130 when the last process with the port open closes the port or the process
1131 terminates. The modem connection is broken.
1135 is set, a connection does not depend on the state of the modem
1138 is clear, the modem status lines are
1141 Under normal circumstances, a call to the
1144 the modem connection to complete. However, if the
1152 immediately without waiting for the connection.
1157 flag is currently unused.
1161 is set then output flow control is controlled by the state
1164 If the object for which the control modes are set is not an asynchronous
1165 serial connection, some of the modes may be ignored; for example, if an
1166 attempt is made to set the baud rate on a network connection to a
1167 terminal on another host, the baud rate may or may not be set on the
1168 connection between that terminal and the machine it is directly connected
1173 field describe the control of
1174 various functions, and are composed of the following
1177 .Bl -tag -width NOKERNINFO -offset indent -compact
1179 /* visual erase for line kill */
1181 /* visually erase chars */
1183 /* enable echoing */
1191 /* visual erase mode for hardcopy */
1193 /* echo control chars as ^(Char) */
1201 /* canonicalize input lines */
1213 /* external processing */
1215 /* stop background jobs from output */
1217 /* output being flushed (state) */
1219 /* no kernel output from
1223 /* XXX retype pending input (state) */
1225 /* don't flush after interrupt */
1230 is set, input characters are echoed back to the terminal. If
1232 is not set, input characters are not echoed.
1240 character causes the terminal
1241 to erase the last character in the current line from the display, if
1242 possible. If there is no character to erase, an implementation may echo
1243 an indication that this was the case or do nothing.
1252 the current line to be discarded and the system echoes the
1265 the current line to be discarded and the system causes
1267 to erase the line from the display.
1273 are set, the system assumes
1274 that the display is a printing device and prints a
1275 backslash and the erased characters when processing
1277 characters, followed by a forward slash.
1281 is set, the system echoes control characters
1282 in a visible fashion using a caret followed by the control character.
1286 is set, the system uses an alternative algorithm
1287 for determining what constitutes a word when processing
1298 character echoes even if
1304 is set, canonical processing is enabled. This enables the
1305 erase and kill edit functions, and the assembly of input characters into
1312 .Sx "Canonical Mode Input Processing" .
1316 is not set, read requests are satisfied directly from the input
1317 queue. A read is not satisfied until at least
1320 received or the timeout value
1322 expired between bytes. The time value
1323 represents tenths of seconds. See
1324 .Sx "Noncanonical Mode Input Processing"
1329 is set, each input character is checked against the special
1335 (job control only). If an input
1336 character matches one of these control characters, the function
1337 associated with that character is performed. If
1340 checking is done. Thus these special input functions are possible only
1347 is set, implementation-defined functions are recognized
1348 from the input data. How
1357 is implementation defined.
1361 implementation-defined functions are not recognized, and the
1362 corresponding input characters are not processed as described for
1371 is set, the normal flush of the input and output queues
1384 is sent to the process group of a process that tries to write to
1385 its controlling terminal if it is not in the foreground process group for
1386 that terminal. This signal, by default, stops the members of the process
1387 group. Otherwise, the output generated by that process is output to the
1388 current output stream. Processes that are blocking or ignoring
1390 signals are excepted and allowed to produce output and the
1397 is set, the kernel does not produce a status message
1402 .Ss Special Control Characters
1403 The special control characters values are defined by the array
1405 This table lists the array index, the corresponding special character,
1406 and the system default value. For an accurate list of
1407 the system defaults, consult the header file
1408 .Aq Pa ttydefaults.h .
1410 .Bl -column "Index Name" "Special Character" -offset indent -compact
1411 .It Em "Index Name Special Character Default Value"
1412 .It Dv VEOF Ta EOF Ta \&^D
1413 .It Dv VEOL Ta EOL Ta _POSIX_VDISABLE
1414 .It Dv VEOL2 Ta EOL2 Ta _POSIX_VDISABLE
1415 .It Dv VERASE Ta ERASE Ta \&^? Ql \&\e177
1416 .It Dv VWERASE Ta WERASE Ta \&^W
1417 .It Dv VKILL Ta KILL Ta \&^U
1418 .It Dv VREPRINT Ta REPRINT Ta \&^R
1419 .It Dv VINTR Ta INTR Ta \&^C
1420 .It Dv VQUIT Ta QUIT Ta \&^\e\e Ql \&\e34
1421 .It Dv VSUSP Ta SUSP Ta \&^Z
1422 .It Dv VDSUSP Ta DSUSP Ta \&^Y
1423 .It Dv VSTART Ta START Ta \&^Q
1424 .It Dv VSTOP Ta STOP Ta \&^S
1425 .It Dv VLNEXT Ta LNEXT Ta \&^V
1426 .It Dv VDISCARD Ta DISCARD Ta \&^O
1427 .It Dv VMIN Ta --- Ta \&1
1428 .It Dv VTIME Ta --- Ta \&0
1429 .It Dv VSTATUS Ta STATUS Ta \&^T
1433 value of one of the changeable special control characters (see
1434 .Sx "Special Characters" )
1436 .Dv {_POSIX_VDISABLE} ,
1437 that function is disabled; that is, no input
1438 data is recognized as the disabled special character.
1442 not set, the value of
1443 .Dv {_POSIX_VDISABLE}
1444 has no special meaning for the
1452 The initial values of the flags and control characters
1456 the values in the header
1457 .Aq Pa sys/ttydefaults.h .