2 .\" manual page [] for chat 1.8
5 .\" SS subsection heading
7 .\" IP indented paragraph
9 .TH CHAT 8 "27 Sep 1997" "Chat Version 1.17"
11 chat \- Automated conversational script with a modem
20 The \fIchat\fR program defines a conversational exchange between the
21 computer and the modem.
22 Its primary purpose is to establish the
23 connection between the Point-to-Point Protocol Daemon (\fIpppd\fR) and
24 the remote's \fIpppd\fR process.
28 Read the chat script from the chat \fIfile\fR.
29 The use of this option
30 is mutually exclusive with the chat script parameters.
32 have read access to the file.
33 Multiple lines are permitted in the
35 Space or horizontal tab characters should be used to separate
39 Set the timeout for the expected string to be received.
41 is not received within the time limit then the reply string is not
43 An alternate reply may be sent or the script will fail if there
44 is no alternate reply string.
45 A failed script will cause the
46 \fIchat\fR program to terminate with a non-zero error code.
48 .B -r \fI<report file>
49 Set the file for output of the report strings.
50 If you use the keyword
51 \fIREPORT\fR, the resulting strings are written to this file.
53 option is not used and you still use \fIREPORT\fR keywords, the
54 \fIstderr\fR file is used for the report strings.
57 Start with the echo option turned on.
58 Echoing may also be turned on
59 or off at specific points in the chat script by using the \fIECHO\fR
61 When echoing is enabled, all output from the modem is echoed
65 Request that the \fIchat\fR script be executed in a verbose mode.
67 \fIchat\fR program will then log the execution state of the chat
68 script as well as all text received from the modem and the output
69 strings sent to the modem. The default is to log through
71 the logging method may be altered with the -S and -s flags.
73 done to the \fIlocal2\fR facility at level \fIinfo\fR for verbose tracing
74 and level \fIerr\fR for some errors.
77 Request that the \fIchat\fR script be executed in a stderr verbose
79 The \fIchat\fR program will then log all text received from the
80 modem and the output strings sent to the modem to the stderr device.
82 device is usually the local console at the station running the chat or
86 Use stderr. All log messages from '-v' and all error messages will be
92 By default, error messages are sent to
94 The use of -S will prevent both log messages from '-v' and
95 error messages from being sent to
98 .B -T \fI<phone number>
99 Pass in an arbitrary string, usually a phone number, that will be
100 substituted for the \\T substitution metacharacter in a send string.
102 .B -U \fI<phone number 2>
103 Pass in a second string, usually a phone number, that will be
104 substituted for the \\U substitution metacharacter in a send string.
105 This is useful when dialing an ISDN terminal adapter that requires two
109 If the script is not specified in a file with the \fI-f\fR option then
110 the script is included as parameters to the \fIchat\fR program.
113 The \fIchat\fR script defines the communications.
115 A script consists of one or more "expect-send" pairs of strings,
116 separated by spaces, with an optional "subexpect-subsend" string pair,
117 separated by a dash as in the following example:
119 ogin:-BREAK-ogin: ppp ssword: hello2u2
121 This line indicates that the \fIchat\fR program should expect the string
122 "ogin:". If it fails to receive a login prompt within the time interval
123 allotted, it is to send a break sequence to the remote and then expect the
124 string "ogin:". If the first "ogin:" is received then the break sequence is
127 Once it received the login prompt the \fIchat\fR program will send the
128 string ppp and then expect the prompt "ssword:". When it receives the
129 prompt for the password, it will send the password hello2u2.
131 A carriage return is normally sent following the reply string.
133 expected in the "expect" string unless it is specifically requested by using
134 the \\r character sequence.
136 The expect sequence should contain only what is needed to identify the
138 Since it is normally stored on a disk file, it should not contain
139 variable information.
140 It is generally not acceptable to look for time
141 strings, network identification strings, or other variable pieces of data as
144 To help correct for characters which may be corrupted during the initial
145 sequence, look for the string "ogin:" rather than "login:". It is possible
146 that the leading "l" character may be received in error and you may never
147 find the string even though it was sent by the system.
149 scripts look for "ogin:" rather than "login:" and "ssword:" rather than
152 A very simple script might look like this:
154 ogin: ppp ssword: hello2u2
156 In other words, expect ....ogin:, send ppp, expect ...ssword:, send hello2u2.
158 In actual practice, simple scripts are rare.
159 At the vary least, you
160 should include sub-expect sequences should the original string not be
162 For example, consider the following script:
164 ogin:--ogin: ppp ssword: hello2u2
166 This would be a better script than the simple one used earlier.
168 for the same login: prompt, however, if one was not received, a single
169 return sequence is sent and then it will look for login: again.
171 noise obscure the first login prompt then sending the empty line will
172 usually generate a login prompt again.
174 Comments can be embedded in the chat script.
175 A comment is a line which
176 starts with the \fB#\fR (hash) character in column 1. Such comment
177 lines are just ignored by the chat program.
178 If a '#' character is to
179 be expected as the first character of the expect sequence, you should
180 quote the expect string.
181 If you want to wait for a prompt that starts with a # (hash)
182 character, you would have to write something like this:
184 # Now wait for the prompt and send logout string
190 Many modems will report the status of the call as a string.
192 strings may be \fBCONNECTED\fR or \fBNO CARRIER\fR or \fBBUSY\fR.
194 is often desirable to terminate the script should the modem fail to
195 connect to the remote.
196 The difficulty is that a script would not know
197 exactly which modem string it may receive.
198 On one attempt, it may
199 receive \fBBUSY\fR while the next time it may receive \fBNO CARRIER\fR.
201 These "abort" strings may be specified in the script using the \fIABORT\fR
203 It is written in the script as in the following example:
205 ABORT BUSY ABORT 'NO CARRIER' '' ATZ OK ATDT5551212 CONNECT
207 This sequence will expect nothing; and then send the string ATZ.
209 expected response to this is the string \fIOK\fR.
210 When it receives \fIOK\fR,
211 the string ATDT5551212 to dial the telephone.
212 The expected string is
214 If the string \fICONNECT\fR is received the remainder of the
216 However, should the modem find a busy telephone, it will
217 send the string \fIBUSY\fR.
218 This will cause the string to match the abort
220 The script will then fail because it found a match to
222 If it received the string \fINO CARRIER\fR, it will abort
224 Either string may be received.
226 terminate the \fIchat\fR script.
227 .SH CLR_ABORT STRINGS
228 This sequence allows for clearing previously set \fBABORT\fR strings.
229 \fBABORT\fR strings are kept in an array of a pre-determined size (at
230 compilation time); \fBCLR_ABORT\fR will reclaim the space for cleared
231 entries so that new strings can use that space.
233 The \fBSAY\fR directive allows the script to send strings to the user
234 at the terminal via standard error. If \fBchat\fR is being run by
235 pppd, and pppd is running as a daemon (detached from its controlling
236 terminal), standard error will normally be redirected to the file
237 /etc/ppp/connect-errors.
239 \fBSAY\fR strings must be enclosed in single or double quotes.
241 carriage return and line feed are needed in the string to be output,
242 you must explicitly add them to your string.
244 The SAY strings could be used to give progress messages in sections of
245 the script where you want to have 'ECHO OFF' but still let the user
246 know what is happening. An example is:
252 SAY "Dialling your ISP...\\n"
258 SAY "Waiting up to 2 minutes for connection ... "
262 SAY "Connected, now logging in ...\\n"
269 SAY "Logged in OK ...\\n"
272 This sequence will only present the SAY strings to the user and all
273 the details of the script will remain hidden.
275 above script works, the user will see:
279 Waiting up to 2 minutes for connection ... Connected, now logging in ...
285 A \fBreport\fR string is similar to the ABORT string.
287 is that the strings, and all characters to the next control character
288 such as a carriage return, are written to the report file.
290 The report strings may be used to isolate the transmission rate of the
291 modem's connect string and return the value to the chat user.
293 analysis of the report string logic occurs in conjunction with the
294 other string processing such as looking for the expect string.
296 of the same string for a report and abort sequence is probably not
297 very useful, however, it is possible.
299 The report strings to no change the completion code of the program.
301 These "report" strings may be specified in the script using the \fIREPORT\fR
303 It is written in the script as in the following example:
305 REPORT CONNECT ABORT BUSY '' ATDT5551212 CONNECT '' ogin: account
307 This sequence will expect nothing; and then send the string
308 ATDT5551212 to dial the telephone.
309 The expected string is
311 If the string \fICONNECT\fR is received the remainder
312 of the script is executed.
313 In addition the program will write to the
314 expect-file the string "CONNECT" plus any characters which follow it
315 such as the connection rate.
316 .SH CLR_REPORT STRINGS
317 This sequence allows for clearing previously set \fBREPORT\fR strings.
318 \fBREPORT\fR strings are kept in an array of a pre-determined size (at
319 compilation time); \fBCLR_REPORT\fR will reclaim the space for cleared
320 entries so that new strings can use that space.
322 The echo options controls whether the output from the modem is echoed
324 This option may be set with the \fI-e\fR option, but
325 it can also be controlled by the \fIECHO\fR keyword.
327 pair \fIECHO\fR \fION\fR enables echoing, and \fIECHO\fR \fIOFF\fR
329 With this keyword you can select which parts of the
330 conversation should be visible.
331 For instance, with the following
350 all output resulting from modem configuration and dialing is not visible,
351 but starting with the \fICONNECT\fR (or \fIBUSY\fR) message, everything
354 The HANGUP options control whether a modem hangup should be considered
355 as an error or not. This option is useful in scripts for dialling
356 systems which will hang up and call your system back. The HANGUP
357 options can be \fBON\fR or \fBOFF\fR.
359 When HANGUP is set OFF and the modem hangs up (e.g., after the first
360 stage of logging in to a callback system), \fBchat\fR will continue
361 running the script (e.g., waiting for the incoming call and second
362 stage login prompt). As soon as the incoming call is connected, you
363 should use the \fBHANGUP ON\fR directive to reinstall normal hang up
364 signal behavior. Here is a (simple) example script:
376 \&'Callback login:' call_back_ID
382 \&'Callback Password:' Call_back_password
392 ogin:--BREAK--ogin: real_account
396 The initial timeout value is 45 seconds.
397 This may be changed using the \fB-t\fR
400 To change the timeout value for the next expect string, the following
403 ATZ OK ATDT5551212 CONNECT TIMEOUT 10 ogin:--ogin: TIMEOUT 5 assword: hello2u2
405 This will change the timeout to 10 seconds when it expects the login:
407 The timeout is then changed to 5 seconds when it looks for the
410 The timeout, once changed, remains in effect until it is changed again.
412 The special reply string of \fIEOT\fR indicates that the chat program
413 should send an EOT character to the remote.
415 End-of-file character sequence.
416 A return character is not sent
419 The EOT sequence may be embedded into the send string using the
422 The special reply string of \fIBREAK\fR will cause a break condition
424 The break is a special signal on the transmitter.
426 normal processing on the receiver is to change the transmission rate.
427 It may be used to cycle through the available transmission rates on
428 the remote until you are able to receive a valid login prompt.
430 The break sequence may be embedded into the send string using the
433 The expect and reply strings may contain escape sequences.
435 sequences are legal in the reply string.
436 Many are legal in the expect.
437 Those which are not valid in the expect sequence are so indicated.
440 Expects or sends a null string.
441 If you send a null string then it will still
442 send the return character.
443 This sequence may either be a pair of apostrophe
447 represents a backspace character.
450 Suppresses the newline at the end of the reply string.
452 method to send a string without a trailing return character.
454 be at the end of the send string.
456 the sequence hello\\c will simply send the characters h, e, l, l, o.
457 .I (not valid in expect.)
460 Delay for one second.
461 The program uses sleep(1) which will delay to a
462 maximum of one second.
463 .I (not valid in expect.)
467 .I (not valid in expect.)
470 Send a newline or linefeed character.
473 Send a null character.
474 The same sequence may be represented by \\0.
475 .I (not valid in expect.)
478 Pause for a fraction of a second.
479 The delay is 1/10th of a second.
480 .I (not valid in expect.)
483 Suppress writing the string to
486 written to the log in its place.
487 .I (not valid in expect.)
490 Send or expect a carriage return.
493 Represents a space character in the string.
494 This may be used when it
495 is not desirable to quote the strings which contains spaces.
497 sequence 'HI TIM' and HI\\sTIM are the same.
500 Send or expect a tab character.
503 Send or expect a backslash character.
506 Collapse the octal digits (ddd) into a single ASCII character and send that
508 .I (some characters are not valid in expect.)
511 Substitute the sequence with the control character represented by C.
512 For example, the character DC1 (17) is shown as \^^Q.
513 .I (some characters are not valid in expect.)
514 .SH TERMINATION CODES
515 The \fIchat\fR program will terminate with the following completion
519 The normal termination of the program.
520 This indicates that the script
521 was executed without error to the normal conclusion.
524 One or more of the parameters are invalid or an expect string was too
525 large for the internal buffers.
526 This indicates that the program as not
530 An error occurred during the execution of the program.
532 to a read or write operation failing for some reason or chat receiving
533 a signal such as SIGINT.
536 A timeout event occurred when there was an \fIexpect\fR string without
537 having a "-subsend" string.
538 This may mean that you did not program the
539 script correctly for the condition or that some unexpected event has
540 occurred and the expected string could not be found.
543 The first string marked as an \fIABORT\fR condition occurred.
546 The second string marked as an \fIABORT\fR condition occurred.
549 The third string marked as an \fIABORT\fR condition occurred.
552 The fourth string marked as an \fIABORT\fR condition occurred.
555 The other termination codes are also strings marked as an \fIABORT\fR
558 Using the termination code, it is possible to determine which event
559 terminated the script.
560 It is possible to decide if the string "BUSY"
561 was received from the modem as opposed to "NO DIAL TONE". While the
562 first event may be retried, the second will probably have little
563 chance of succeeding during a retry.
565 Additional information about \fIchat\fR scripts may be found with UUCP
567 The \fIchat\fR script was taken from the ideas proposed
568 by the scripts used by the \fIuucico\fR program.
570 uucico(1), uucp(1), syslog(3), syslogd(8).
572 The \fIchat\fR program is in public domain.
573 This is not the GNU public
575 If it breaks then you get to keep both pieces.
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