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1 | '\" |
2 | '\" Copyright (c) 1993 The Regents of the University of California. | |
3 | '\" Copyright (c) 1994-1996 Sun Microsystems, Inc. | |
4 | '\" | |
5 | '\" See the file "license.terms" for information on usage and redistribution | |
6 | '\" of this file, and for a DISCLAIMER OF ALL WARRANTIES. | |
7 | '\" | |
8 | '\" RCS: @(#) $Id: open.n,v 1.16.2.3 2005/04/19 16:30:21 davygrvy Exp $ | |
9 | '\" | |
10 | '\" The definitions below are for supplemental macros used in Tcl/Tk | |
11 | '\" manual entries. | |
12 | '\" | |
13 | '\" .AP type name in/out ?indent? | |
14 | '\" Start paragraph describing an argument to a library procedure. | |
15 | '\" type is type of argument (int, etc.), in/out is either "in", "out", | |
16 | '\" or "in/out" to describe whether procedure reads or modifies arg, | |
17 | '\" and indent is equivalent to second arg of .IP (shouldn't ever be | |
18 | '\" needed; use .AS below instead) | |
19 | '\" | |
20 | '\" .AS ?type? ?name? | |
21 | '\" Give maximum sizes of arguments for setting tab stops. Type and | |
22 | '\" name are examples of largest possible arguments that will be passed | |
23 | '\" to .AP later. If args are omitted, default tab stops are used. | |
24 | '\" | |
25 | '\" .BS | |
26 | '\" Start box enclosure. From here until next .BE, everything will be | |
27 | '\" enclosed in one large box. | |
28 | '\" | |
29 | '\" .BE | |
30 | '\" End of box enclosure. | |
31 | '\" | |
32 | '\" .CS | |
33 | '\" Begin code excerpt. | |
34 | '\" | |
35 | '\" .CE | |
36 | '\" End code excerpt. | |
37 | '\" | |
38 | '\" .VS ?version? ?br? | |
39 | '\" Begin vertical sidebar, for use in marking newly-changed parts | |
40 | '\" of man pages. The first argument is ignored and used for recording | |
41 | '\" the version when the .VS was added, so that the sidebars can be | |
42 | '\" found and removed when they reach a certain age. If another argument | |
43 | '\" is present, then a line break is forced before starting the sidebar. | |
44 | '\" | |
45 | '\" .VE | |
46 | '\" End of vertical sidebar. | |
47 | '\" | |
48 | '\" .DS | |
49 | '\" Begin an indented unfilled display. | |
50 | '\" | |
51 | '\" .DE | |
52 | '\" End of indented unfilled display. | |
53 | '\" | |
54 | '\" .SO | |
55 | '\" Start of list of standard options for a Tk widget. The | |
56 | '\" options follow on successive lines, in four columns separated | |
57 | '\" by tabs. | |
58 | '\" | |
59 | '\" .SE | |
60 | '\" End of list of standard options for a Tk widget. | |
61 | '\" | |
62 | '\" .OP cmdName dbName dbClass | |
63 | '\" Start of description of a specific option. cmdName gives the | |
64 | '\" option's name as specified in the class command, dbName gives | |
65 | '\" the option's name in the option database, and dbClass gives | |
66 | '\" the option's class in the option database. | |
67 | '\" | |
68 | '\" .UL arg1 arg2 | |
69 | '\" Print arg1 underlined, then print arg2 normally. | |
70 | '\" | |
71 | '\" RCS: @(#) $Id: man.macros,v 1.4 2000/08/25 06:18:32 ericm Exp $ | |
72 | '\" | |
73 | '\" # Set up traps and other miscellaneous stuff for Tcl/Tk man pages. | |
74 | .if t .wh -1.3i ^B | |
75 | .nr ^l \n(.l | |
76 | .ad b | |
77 | '\" # Start an argument description | |
78 | .de AP | |
79 | .ie !"\\$4"" .TP \\$4 | |
80 | .el \{\ | |
81 | . ie !"\\$2"" .TP \\n()Cu | |
82 | . el .TP 15 | |
83 | .\} | |
84 | .ta \\n()Au \\n()Bu | |
85 | .ie !"\\$3"" \{\ | |
86 | \&\\$1 \\fI\\$2\\fP (\\$3) | |
87 | .\".b | |
88 | .\} | |
89 | .el \{\ | |
90 | .br | |
91 | .ie !"\\$2"" \{\ | |
92 | \&\\$1 \\fI\\$2\\fP | |
93 | .\} | |
94 | .el \{\ | |
95 | \&\\fI\\$1\\fP | |
96 | .\} | |
97 | .\} | |
98 | .. | |
99 | '\" # define tabbing values for .AP | |
100 | .de AS | |
101 | .nr )A 10n | |
102 | .if !"\\$1"" .nr )A \\w'\\$1'u+3n | |
103 | .nr )B \\n()Au+15n | |
104 | .\" | |
105 | .if !"\\$2"" .nr )B \\w'\\$2'u+\\n()Au+3n | |
106 | .nr )C \\n()Bu+\\w'(in/out)'u+2n | |
107 | .. | |
108 | .AS Tcl_Interp Tcl_CreateInterp in/out | |
109 | '\" # BS - start boxed text | |
110 | '\" # ^y = starting y location | |
111 | '\" # ^b = 1 | |
112 | .de BS | |
113 | .br | |
114 | .mk ^y | |
115 | .nr ^b 1u | |
116 | .if n .nf | |
117 | .if n .ti 0 | |
118 | .if n \l'\\n(.lu\(ul' | |
119 | .if n .fi | |
120 | .. | |
121 | '\" # BE - end boxed text (draw box now) | |
122 | .de BE | |
123 | .nf | |
124 | .ti 0 | |
125 | .mk ^t | |
126 | .ie n \l'\\n(^lu\(ul' | |
127 | .el \{\ | |
128 | .\" Draw four-sided box normally, but don't draw top of | |
129 | .\" box if the box started on an earlier page. | |
130 | .ie !\\n(^b-1 \{\ | |
131 | \h'-1.5n'\L'|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul' | |
132 | .\} | |
133 | .el \}\ | |
134 | \h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul' | |
135 | .\} | |
136 | .\} | |
137 | .fi | |
138 | .br | |
139 | .nr ^b 0 | |
140 | .. | |
141 | '\" # VS - start vertical sidebar | |
142 | '\" # ^Y = starting y location | |
143 | '\" # ^v = 1 (for troff; for nroff this doesn't matter) | |
144 | .de VS | |
145 | .if !"\\$2"" .br | |
146 | .mk ^Y | |
147 | .ie n 'mc \s12\(br\s0 | |
148 | .el .nr ^v 1u | |
149 | .. | |
150 | '\" # VE - end of vertical sidebar | |
151 | .de VE | |
152 | .ie n 'mc | |
153 | .el \{\ | |
154 | .ev 2 | |
155 | .nf | |
156 | .ti 0 | |
157 | .mk ^t | |
158 | \h'|\\n(^lu+3n'\L'|\\n(^Yu-1v\(bv'\v'\\n(^tu+1v-\\n(^Yu'\h'-|\\n(^lu+3n' | |
159 | .sp -1 | |
160 | .fi | |
161 | .ev | |
162 | .\} | |
163 | .nr ^v 0 | |
164 | .. | |
165 | '\" # Special macro to handle page bottom: finish off current | |
166 | '\" # box/sidebar if in box/sidebar mode, then invoked standard | |
167 | '\" # page bottom macro. | |
168 | .de ^B | |
169 | .ev 2 | |
170 | 'ti 0 | |
171 | 'nf | |
172 | .mk ^t | |
173 | .if \\n(^b \{\ | |
174 | .\" Draw three-sided box if this is the box's first page, | |
175 | .\" draw two sides but no top otherwise. | |
176 | .ie !\\n(^b-1 \h'-1.5n'\L'|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\h'|0u'\c | |
177 | .el \h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\h'|0u'\c | |
178 | .\} | |
179 | .if \\n(^v \{\ | |
180 | .nr ^x \\n(^tu+1v-\\n(^Yu | |
181 | \kx\h'-\\nxu'\h'|\\n(^lu+3n'\ky\L'-\\n(^xu'\v'\\n(^xu'\h'|0u'\c | |
182 | .\} | |
183 | .bp | |
184 | 'fi | |
185 | .ev | |
186 | .if \\n(^b \{\ | |
187 | .mk ^y | |
188 | .nr ^b 2 | |
189 | .\} | |
190 | .if \\n(^v \{\ | |
191 | .mk ^Y | |
192 | .\} | |
193 | .. | |
194 | '\" # DS - begin display | |
195 | .de DS | |
196 | .RS | |
197 | .nf | |
198 | .sp | |
199 | .. | |
200 | '\" # DE - end display | |
201 | .de DE | |
202 | .fi | |
203 | .RE | |
204 | .sp | |
205 | .. | |
206 | '\" # SO - start of list of standard options | |
207 | .de SO | |
208 | .SH "STANDARD OPTIONS" | |
209 | .LP | |
210 | .nf | |
211 | .ta 5.5c 11c | |
212 | .ft B | |
213 | .. | |
214 | '\" # SE - end of list of standard options | |
215 | .de SE | |
216 | .fi | |
217 | .ft R | |
218 | .LP | |
219 | See the \\fBoptions\\fR manual entry for details on the standard options. | |
220 | .. | |
221 | '\" # OP - start of full description for a single option | |
222 | .de OP | |
223 | .LP | |
224 | .nf | |
225 | .ta 4c | |
226 | Command-Line Name: \\fB\\$1\\fR | |
227 | Database Name: \\fB\\$2\\fR | |
228 | Database Class: \\fB\\$3\\fR | |
229 | .fi | |
230 | .IP | |
231 | .. | |
232 | '\" # CS - begin code excerpt | |
233 | .de CS | |
234 | .RS | |
235 | .nf | |
236 | .ta .25i .5i .75i 1i | |
237 | .. | |
238 | '\" # CE - end code excerpt | |
239 | .de CE | |
240 | .fi | |
241 | .RE | |
242 | .. | |
243 | .de UL | |
244 | \\$1\l'|0\(ul'\\$2 | |
245 | .. | |
246 | .TH open n 8.3 Tcl "Tcl Built-In Commands" | |
247 | .BS | |
248 | '\" Note: do not modify the .SH NAME line immediately below! | |
249 | .SH NAME | |
250 | open \- Open a file-based or command pipeline channel | |
251 | .SH SYNOPSIS | |
252 | .sp | |
253 | \fBopen \fIfileName\fR | |
254 | .br | |
255 | \fBopen \fIfileName access\fR | |
256 | .br | |
257 | \fBopen \fIfileName access permissions\fR | |
258 | .BE | |
259 | ||
260 | .SH DESCRIPTION | |
261 | .PP | |
262 | This command opens a file, serial port, or command pipeline and returns a | |
263 | channel identifier that may be used in future invocations of commands like | |
264 | \fBread\fR, \fBputs\fR, and \fBclose\fR. | |
265 | If the first character of \fIfileName\fR is not \fB|\fR then | |
266 | the command opens a file: | |
267 | \fIfileName\fR gives the name of the file to open, and it must conform to the | |
268 | conventions described in the \fBfilename\fR manual entry. | |
269 | .PP | |
270 | The \fIaccess\fR argument, if present, indicates the way in which the file | |
271 | (or command pipeline) is to be accessed. | |
272 | In the first form \fIaccess\fR may have any of the following values: | |
273 | .TP 15 | |
274 | \fBr\fR | |
275 | Open the file for reading only; the file must already exist. This is the | |
276 | default value if \fIaccess\fR is not specified. | |
277 | .TP 15 | |
278 | \fBr+\fR | |
279 | Open the file for both reading and writing; the file must | |
280 | already exist. | |
281 | .TP 15 | |
282 | \fBw\fR | |
283 | Open the file for writing only. Truncate it if it exists. If it doesn't | |
284 | exist, create a new file. | |
285 | .TP 15 | |
286 | \fBw+\fR | |
287 | Open the file for reading and writing. Truncate it if it exists. | |
288 | If it doesn't exist, create a new file. | |
289 | .TP 15 | |
290 | \fBa\fR | |
291 | Open the file for writing only. If the file doesn't exist, | |
292 | create a new empty file. | |
293 | Set the initial access position to the end of the file. | |
294 | .TP 15 | |
295 | \fBa+\fR | |
296 | Open the file for reading and writing. If the file doesn't exist, | |
297 | create a new empty file. | |
298 | Set the initial access position to the end of the file. | |
299 | .PP | |
300 | In the second form, \fIaccess\fR consists of a list of any of the | |
301 | following flags, all of which have the standard POSIX meanings. | |
302 | One of the flags must be either \fBRDONLY\fR, \fBWRONLY\fR or \fBRDWR\fR. | |
303 | .TP 15 | |
304 | \fBRDONLY\fR | |
305 | Open the file for reading only. | |
306 | .TP 15 | |
307 | \fBWRONLY\fR | |
308 | Open the file for writing only. | |
309 | .TP 15 | |
310 | \fBRDWR\fR | |
311 | Open the file for both reading and writing. | |
312 | .TP 15 | |
313 | \fBAPPEND\fR | |
314 | Set the file pointer to the end of the file prior to each write. | |
315 | .TP 15 | |
316 | \fBCREAT\fR | |
317 | Create the file if it doesn't already exist (without this flag it | |
318 | is an error for the file not to exist). | |
319 | .TP 15 | |
320 | \fBEXCL\fR | |
321 | If \fBCREAT\fR is also specified, an error is returned if the | |
322 | file already exists. | |
323 | .TP 15 | |
324 | \fBNOCTTY\fR | |
325 | If the file is a terminal device, this flag prevents the file from | |
326 | becoming the controlling terminal of the process. | |
327 | .TP 15 | |
328 | \fBNONBLOCK\fR | |
329 | Prevents the process from blocking while opening the file, and | |
330 | possibly in subsequent I/O operations. The exact behavior of | |
331 | this flag is system- and device-dependent; its use is discouraged | |
332 | (it is better to use the \fBfconfigure\fR command to put a file | |
333 | in nonblocking mode). | |
334 | For details refer to your system documentation on the \fBopen\fR system | |
335 | call's \fBO_NONBLOCK\fR flag. | |
336 | .TP 15 | |
337 | \fBTRUNC\fR | |
338 | If the file exists it is truncated to zero length. | |
339 | .PP | |
340 | If a new file is created as part of opening it, \fIpermissions\fR | |
341 | (an integer) is used to set the permissions for the new file in | |
342 | conjunction with the process's file mode creation mask. | |
343 | \fIPermissions\fR defaults to 0666. | |
344 | .PP | |
345 | Note that if you are going to be reading or writing binary data from | |
346 | the channel created by this command, you should use the | |
347 | \fBfconfigure\fR command to change the \fB-translation\fR option of | |
348 | the channel to \fBbinary\fR before transferring any binary data. This | |
349 | is in contrast to the ``b'' character passed as part of the equivalent | |
350 | of the \fIaccess\fR parameter to some versions of the C library | |
351 | \fIfopen()\fR function. | |
352 | ||
353 | .SH "COMMAND PIPELINES" | |
354 | .PP | |
355 | If the first character of \fIfileName\fR is ``|'' then the | |
356 | remaining characters of \fIfileName\fR are treated as a list of arguments | |
357 | that describe a command pipeline to invoke, in the same style as the | |
358 | arguments for \fBexec\fR. | |
359 | In this case, the channel identifier returned by \fBopen\fR may be used | |
360 | to write to the command's input pipe or read from its output pipe, | |
361 | depending on the value of \fIaccess\fR. | |
362 | If write-only access is used (e.g. \fIaccess\fR is \fBw\fR), then | |
363 | standard output for the pipeline is directed to the current standard | |
364 | output unless overridden by the command. | |
365 | If read-only access is used (e.g. \fIaccess\fR is \fBr\fR), | |
366 | standard input for the pipeline is taken from the current standard | |
367 | input unless overridden by the command. | |
368 | The id of the spawned process is accessible through the \fBpid\fR | |
369 | command, using the channel id returned by \fBopen\fR as argument. | |
370 | .PP | |
371 | If the command (or one of the commands) executed in the command | |
372 | pipeline returns an error (according to the definition in \fBexec\fR), | |
373 | a Tcl error is generated when \fBclose\fR is called on the channel | |
374 | unless the pipeline is in non-blocking mode then no exit status is | |
375 | returned (a silent \fBclose\fR with -blocking 0). | |
376 | .PP | |
377 | It is often useful to use the \fBfileevent\fR command with pipelines | |
378 | so other processing may happen at the same time as running the command | |
379 | in the background. | |
380 | .VS 8.4 | |
381 | .SH "SERIAL COMMUNICATIONS" | |
382 | .PP | |
383 | If \fIfileName\fR refers to a serial port, then the specified serial port | |
384 | is opened and initialized in a platform-dependent manner. Acceptable | |
385 | values for the \fIfileName\fR to use to open a serial port are described in | |
386 | the PORTABILITY ISSUES section. | |
387 | .PP | |
388 | The \fBfconfigure\fR command can be used to query and set additional | |
389 | configuration options specific to serial ports (where supported): | |
390 | .TP | |
391 | \fB\-mode\fR \fIbaud\fB,\fIparity\fB,\fIdata\fB,\fIstop\fR | |
392 | This option is a set of 4 comma-separated values: the baud rate, parity, | |
393 | number of data bits, and number of stop bits for this serial port. The | |
394 | \fIbaud\fR rate is a simple integer that specifies the connection speed. | |
395 | \fIParity\fR is one of the following letters: \fBn\fR, \fBo\fR, \fBe\fR, | |
396 | \fBm\fR, \fBs\fR; respectively signifying the parity options of ``none'', | |
397 | ``odd'', ``even'', ``mark'', or ``space''. \fIData\fR is the number of | |
398 | data bits and should be an integer from 5 to 8, while \fIstop\fR is the | |
399 | number of stop bits and should be the integer 1 or 2. | |
400 | .TP | |
401 | \fB\-handshake\fR \fItype\fR | |
402 | (Windows and Unix). This option is used to setup automatic handshake | |
403 | control. Note that not all handshake types maybe supported by your operating | |
404 | system. The \fItype\fR parameter is case-independent. | |
405 | .sp | |
406 | If \fItype\fR is \fBnone\fR then any handshake is switched off. | |
407 | \fBrtscts\fR activates hardware handshake. Hardware handshake signals | |
408 | are described below. | |
409 | For software handshake \fBxonxoff\fR the handshake characters can be redefined | |
410 | with \fB-xchar\fR. | |
411 | An additional hardware handshake \fBdtrdsr\fR is available only under Windows. | |
412 | There is no default handshake configuration, the initial value depends | |
413 | on your operating system settings. | |
414 | The \fB-handshake\fR option cannot be queried. | |
415 | .TP | |
416 | \fB\-queue\fR | |
417 | (Windows and Unix). The \fB-queue\fR option can only be queried. | |
418 | It returns a list of two integers representing the current number | |
419 | of bytes in the input and output queue respectively. | |
420 | .TP | |
421 | \fB\-timeout\fR \fImsec\fR | |
422 | (Windows and Unix). This option is used to set the timeout for blocking | |
423 | read operations. It specifies the maximum interval between the | |
424 | reception of two bytes in milliseconds. | |
425 | For Unix systems the granularity is 100 milliseconds. | |
426 | The \fB-timeout\fR option does not affect write operations or | |
427 | nonblocking reads. | |
428 | This option cannot be queried. | |
429 | .TP | |
430 | \fB\-ttycontrol\fR \fI{signal boolean signal boolean ...}\fR | |
431 | (Windows and Unix). This option is used to setup the handshake | |
432 | output lines (see below) permanently or to send a BREAK over the serial line. | |
433 | The \fIsignal\fR names are case-independent. | |
434 | \fB{RTS 1 DTR 0}\fR sets the RTS output to high and the DTR output to low. | |
435 | The BREAK condition (see below) is enabled and disabled with \fB{BREAK 1}\fR and | |
436 | \fB{BREAK 0}\fR respectively. | |
437 | It's not a good idea to change the \fBRTS\fR (or \fBDTR\fR) signal | |
438 | with active hardware handshake \fBrtscts\fR (or \fBdtrdsr\fR). | |
439 | The result is unpredictable. | |
440 | The \fB-ttycontrol\fR option cannot be queried. | |
441 | .TP | |
442 | \fB\-ttystatus\fR | |
443 | (Windows and Unix). The \fB-ttystatus\fR option can only be | |
444 | queried. It returns the current modem status and handshake input signals | |
445 | (see below). | |
446 | The result is a list of signal,value pairs with a fixed order, | |
447 | e.g. \fB{CTS 1 DSR 0 RING 1 DCD 0}\fR. | |
448 | The \fIsignal\fR names are returned upper case. | |
449 | .TP | |
450 | \fB\-xchar\fR \fI{xonChar xoffChar}\fR | |
451 | (Windows and Unix). This option is used to query or change the software | |
452 | handshake characters. Normally the operating system default should be | |
453 | DC1 (0x11) and DC3 (0x13) representing the ASCII standard | |
454 | XON and XOFF characters. | |
455 | .TP | |
456 | \fB\-pollinterval\fR \fImsec\fR | |
457 | (Windows only). This option is used to set the maximum time between | |
458 | polling for fileevents. | |
459 | This affects the time interval between checking for events throughout the Tcl | |
460 | interpreter (the smallest value always wins). Use this option only if | |
461 | you want to poll the serial port more or less often than 10 msec | |
462 | (the default). | |
463 | .TP | |
464 | \fB\-sysbuffer\fR \fIinSize\fR | |
465 | .TP | |
466 | \fB\-sysbuffer\fR \fI{inSize outSize}\fR | |
467 | (Windows only). This option is used to change the size of Windows | |
468 | system buffers for a serial channel. Especially at higher communication | |
469 | rates the default input buffer size of 4096 bytes can overrun | |
470 | for latent systems. The first form specifies the input buffer size, | |
471 | in the second form both input and output buffers are defined. | |
472 | .TP | |
473 | \fB\-lasterror\fR | |
474 | (Windows only). This option is query only. | |
475 | In case of a serial communication error, \fBread\fR or \fBputs\fR | |
476 | returns a general Tcl file I/O error. | |
477 | \fBfconfigure -lasterror\fR can be called to get a list of error details. | |
478 | See below for an explanation of the various error codes. | |
479 | ||
480 | .SH "SERIAL PORT SIGNALS" | |
481 | .PP | |
482 | RS-232 is the most commonly used standard electrical interface for serial | |
483 | communications. A negative voltage (-3V..-12V) define a mark (on=1) bit and | |
484 | a positive voltage (+3..+12V) define a space (off=0) bit (RS-232C). The | |
485 | following signals are specified for incoming and outgoing data, status | |
486 | lines and handshaking. Here we are using the terms \fIworkstation\fR for | |
487 | your computer and \fImodem\fR for the external device, because some signal | |
488 | names (DCD, RI) come from modems. Of course your external device may use | |
489 | these signal lines for other purposes. | |
490 | ||
491 | .IP \fBTXD(output)\fR | |
492 | \fBTransmitted Data:\fR Outgoing serial data. | |
493 | .IP \fBRXD(input)\fR | |
494 | \fBReceived Data:\fRIncoming serial data. | |
495 | .IP \fBRTS(output)\fR | |
496 | \fBRequest To Send:\fR This hardware handshake line informs the modem that | |
497 | your workstation is ready to receive data. Your workstation may | |
498 | automatically reset this signal to indicate that the input buffer is full. | |
499 | .IP \fBCTS(input)\fR | |
500 | \fBClear To Send:\fR The complement to RTS. Indicates that the modem is | |
501 | ready to receive data. | |
502 | .IP \fBDTR(output)\fR | |
503 | \fBData Terminal Ready:\fR This signal tells the modem that the workstation | |
504 | is ready to establish a link. DTR is often enabled automatically whenever a | |
505 | serial port is opened. | |
506 | .IP \fBDSR(input)\fR | |
507 | \fBData Set Ready:\fR The complement to DTR. Tells the workstation that the | |
508 | modem is ready to establish a link. | |
509 | .IP \fBDCD(input)\fR | |
510 | \fBData Carrier Detect:\fR This line becomes active when a modem detects | |
511 | a "Carrier" signal. | |
512 | .IP \fBRI(input)\fR | |
513 | \fBRing Indicator:\fR Goes active when the modem detects an incoming call. | |
514 | .IP \fBBREAK\fR | |
515 | A BREAK condition is not a hardware signal line, but a logical zero on the | |
516 | TXD or RXD lines for a long period of time, usually 250 to 500 | |
517 | milliseconds. Normally a receive or transmit data signal stays at the mark | |
518 | (on=1) voltage until the next character is transferred. A BREAK is sometimes | |
519 | used to reset the communications line or change the operating mode of | |
520 | communications hardware. | |
521 | ||
522 | .SH "ERROR CODES (Windows only)" | |
523 | .PP | |
524 | A lot of different errors may occur during serial read operations or during | |
525 | event polling in background. The external device may have been switched | |
526 | off, the data lines may be noisy, system buffers may overrun or your mode | |
527 | settings may be wrong. That's why a reliable software should always | |
528 | \fBcatch\fR serial read operations. In cases of an error Tcl returns a | |
529 | general file I/O error. Then \fBfconfigure -lasterror\fR may help to | |
530 | locate the problem. The following error codes may be returned. | |
531 | ||
532 | .TP 10 | |
533 | \fBRXOVER\fR | |
534 | Windows input buffer overrun. The data comes faster than your scripts reads | |
535 | it or your system is overloaded. Use \fBfconfigure -sysbuffer\fR to avoid a | |
536 | temporary bottleneck and/or make your script faster. | |
537 | .TP 10 | |
538 | \fBTXFULL\fR | |
539 | Windows output buffer overrun. Complement to RXOVER. This error should | |
540 | practically not happen, because Tcl cares about the output buffer status. | |
541 | .TP 10 | |
542 | \fBOVERRUN\fR | |
543 | UART buffer overrun (hardware) with data lost. | |
544 | The data comes faster than the system driver receives it. | |
545 | Check your advanced serial port settings to enable the FIFO (16550) buffer | |
546 | and/or setup a lower(1) interrupt threshold value. | |
547 | .TP 10 | |
548 | \fBRXPARITY\fR | |
549 | A parity error has been detected by your UART. | |
550 | Wrong parity settings with \fBfconfigure -mode\fR or a noisy data line (RXD) | |
551 | may cause this error. | |
552 | .TP 10 | |
553 | \fBFRAME\fR | |
554 | A stop-bit error has been detected by your UART. | |
555 | Wrong mode settings with \fBfconfigure -mode\fR or a noisy data line (RXD) | |
556 | may cause this error. | |
557 | .TP 10 | |
558 | \fBBREAK\fR | |
559 | A BREAK condition has been detected by your UART (see above). | |
560 | .VE | |
561 | ||
562 | .SH "PORTABILITY ISSUES" | |
563 | .TP | |
564 | \fBWindows \fR(all versions) | |
565 | Valid values for \fIfileName\fR to open a serial port are of the form | |
566 | \fBcom\fIX\fB:\fR, where \fIX\fR is a number, generally from 1 to 4. | |
567 | This notation only works for serial ports from 1 to 9, if the system | |
568 | happens to have more than four. An attempt to open a serial port that | |
569 | does not exist or has a number greater than 9 will fail. An alternate | |
570 | form of opening serial ports is to use the filename \fB\e\e.\ecomX\fR, | |
571 | where X is any number that corresponds to a serial port; please note | |
572 | that this method is considerably slower on Windows 95 and Windows 98. | |
573 | .TP | |
574 | \fBWindows NT\fR | |
575 | When running Tcl interactively, there may be some strange interactions | |
576 | between the real console, if one is present, and a command pipeline that uses | |
577 | standard input or output. If a command pipeline is opened for reading, some | |
578 | of the lines entered at the console will be sent to the command pipeline and | |
579 | some will be sent to the Tcl evaluator. If a command pipeline is opened for | |
580 | writing, keystrokes entered into the console are not visible until the | |
581 | pipe is closed. This behavior occurs whether the command pipeline is | |
582 | executing 16-bit or 32-bit applications. These problems only occur because | |
583 | both Tcl and the child application are competing for the console at | |
584 | the same time. If the command pipeline is started from a script, so that Tcl | |
585 | is not accessing the console, or if the command pipeline does not use | |
586 | standard input or output, but is redirected from or to a file, then the | |
587 | above problems do not occur. | |
588 | .TP | |
589 | \fBWindows 95\fR | |
590 | A command pipeline that executes a 16-bit DOS application cannot be opened | |
591 | for both reading and writing, since 16-bit DOS applications that receive | |
592 | standard input from a pipe and send standard output to a pipe run | |
593 | synchronously. Command pipelines that do not execute 16-bit DOS | |
594 | applications run asynchronously and can be opened for both reading and | |
595 | writing. | |
596 | .sp | |
597 | When running Tcl interactively, there may be some strange interactions | |
598 | between the real console, if one is present, and a command pipeline that uses | |
599 | standard input or output. If a command pipeline is opened for reading from | |
600 | a 32-bit application, some of the keystrokes entered at the console will be | |
601 | sent to the command pipeline and some will be sent to the Tcl evaluator. If | |
602 | a command pipeline is opened for writing to a 32-bit application, no output | |
603 | is visible on the console until the pipe is closed. These problems only | |
604 | occur because both Tcl and the child application are competing for the | |
605 | console at the same time. If the command pipeline is started from a script, | |
606 | so that Tcl is not accessing the console, or if the command pipeline does | |
607 | not use standard input or output, but is redirected from or to a file, then | |
608 | the above problems do not occur. | |
609 | .sp | |
610 | Whether or not Tcl is running interactively, if a command pipeline is opened | |
611 | for reading from a 16-bit DOS application, the call to \fBopen\fR will not | |
612 | return until end-of-file has been received from the command pipeline's | |
613 | standard output. If a command pipeline is opened for writing to a 16-bit DOS | |
614 | application, no data will be sent to the command pipeline's standard output | |
615 | until the pipe is actually closed. This problem occurs because 16-bit DOS | |
616 | applications are run synchronously, as described above. | |
617 | .TP | |
618 | \fBMacintosh\fR | |
619 | Opening a serial port is not currently implemented under Macintosh. | |
620 | .sp | |
621 | Opening a command pipeline is not supported under Macintosh, since | |
622 | applications do not support the concept of standard input or output. | |
623 | .TP | |
624 | \fBUnix\fR\0\0\0\0\0\0\0 | |
625 | Valid values for \fIfileName\fR to open a serial port are generally of the | |
626 | form \fB/dev/tty\fIX\fR, where \fIX\fR is \fBa\fR or \fBb\fR, but the name | |
627 | of any pseudo-file that maps to a serial port may be used. | |
628 | .VS 8.4 | |
629 | Advanced configuration options are only supported for serial ports | |
630 | when Tcl is built to use the POSIX serial interface. | |
631 | .VE 8.4 | |
632 | .sp | |
633 | When running Tcl interactively, there may be some strange interactions | |
634 | between the console, if one is present, and a command pipeline that uses | |
635 | standard input. If a command pipeline is opened for reading, some | |
636 | of the lines entered at the console will be sent to the command pipeline and | |
637 | some will be sent to the Tcl evaluator. This problem only occurs because | |
638 | both Tcl and the child application are competing for the console at the | |
639 | same time. If the command pipeline is started from a script, so that Tcl is | |
640 | not accessing the console, or if the command pipeline does not use standard | |
641 | input, but is redirected from a file, then the above problem does not occur. | |
642 | .LP | |
643 | See the PORTABILITY ISSUES section of the \fBexec\fR command for additional | |
644 | information not specific to command pipelines about executing | |
645 | applications on the various platforms | |
646 | .SH "EXAMPLE" | |
647 | Open a command pipeline and catch any errors: | |
648 | .CS | |
649 | set fl [\fBopen\fR "| ls this_file_does_not_exist"] | |
650 | set data [read $fl] | |
651 | if {[catch {close $fl} err]} { | |
652 | puts "ls command failed: $err" | |
653 | } | |
654 | .CE | |
655 | ||
656 | .SH "SEE ALSO" | |
657 | file(n), close(n), filename(n), fconfigure(n), gets(n), read(n), | |
658 | puts(n), exec(n), pid(n), fopen(3) | |
659 | ||
660 | .SH KEYWORDS | |
661 | access mode, append, create, file, non-blocking, open, permissions, | |
662 | pipeline, process, serial |