2 .\" manual page [] for chat 1.8
3 .\" $Id: chat.8,v 1.8 1999/05/12 06:13:22 paulus Exp $
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. Its primary purpose is to establish the
22 connection between the Point-to-Point Protocol Daemon (\fIpppd\fR) and
23 the remote's \fIpppd\fR process.
27 Read the chat script from the chat \fIfile\fR. The use of this option
28 is mutually exclusive with the chat script parameters. The user must
29 have read access to the file. Multiple lines are permitted in the
30 file. Space or horizontal tab characters should be used to separate
34 Set the timeout for the expected string to be received. If the string
35 is not received within the time limit then the reply string is not
36 sent. An alternate reply may be sent or the script will fail if there
37 is no alternate reply string. A failed script will cause the
38 \fIchat\fR program to terminate with a non-zero error code.
40 .B -r \fI<report file>
41 Set the file for output of the report strings. If you use the keyword
42 \fIREPORT\fR, the resulting strings are written to this file. If this
43 option is not used and you still use \fIREPORT\fR keywords, the
44 \fIstderr\fR file is used for the report strings.
47 Start with the echo option turned on. Echoing may also be turned on
48 or off at specific points in the chat script by using the \fIECHO\fR
49 keyword. When echoing is enabled, all output from the modem is echoed
53 Request that the \fIchat\fR script be executed in a verbose mode. The
54 \fIchat\fR program will then log the execution state of the chat
55 script as well as all text received from the modem and the output
56 strings sent to the modem. The default is to log through the SYSLOG;
57 the logging method may be altered with the -S and -s flags.
60 Request that the \fIchat\fR script be executed in a stderr verbose
61 mode. The \fIchat\fR program will then log all text received from the
62 modem and the output strings sent to the modem to the stderr device. This
63 device is usually the local console at the station running the chat or
67 Use stderr. All log messages from '-v' and all error messages will be
71 Do not use the SYSLOG. By default, error messages are sent to the
72 SYSLOG. The use of -S will prevent both log messages from '-v' and
73 error messages from being sent to the SYSLOG.
75 .B -T \fI<phone number>
76 Pass in an arbitary string, usually a phone number, that will be
77 substituted for the \\T substitution metacharacter in a send string.
79 .B -U \fI<phone number 2>
80 Pass in a second string, usually a phone number, that will be
81 substituted for the \\U substitution metacharacter in a send string.
82 This is useful when dialing an ISDN terminal adapter that requires two
86 If the script is not specified in a file with the \fI-f\fR option then
87 the script is included as parameters to the \fIchat\fR program.
90 The \fIchat\fR script defines the communications.
92 A script consists of one or more "expect-send" pairs of strings,
93 separated by spaces, with an optional "subexpect-subsend" string pair,
94 separated by a dash as in the following example:
96 ogin:-BREAK-ogin: ppp ssword: hello2u2
98 This line indicates that the \fIchat\fR program should expect the string
99 "ogin:". If it fails to receive a login prompt within the time interval
100 allotted, it is to send a break sequence to the remote and then expect the
101 string "ogin:". If the first "ogin:" is received then the break sequence is
104 Once it received the login prompt the \fIchat\fR program will send the
105 string ppp and then expect the prompt "ssword:". When it receives the
106 prompt for the password, it will send the password hello2u2.
108 A carriage return is normally sent following the reply string. It is not
109 expected in the "expect" string unless it is specifically requested by using
110 the \\r character sequence.
112 The expect sequence should contain only what is needed to identify the
113 string. Since it is normally stored on a disk file, it should not contain
114 variable information. It is generally not acceptable to look for time
115 strings, network identification strings, or other variable pieces of data as
118 To help correct for characters which may be corrupted during the initial
119 sequence, look for the string "ogin:" rather than "login:". It is possible
120 that the leading "l" character may be received in error and you may never
121 find the string even though it was sent by the system. For this reason,
122 scripts look for "ogin:" rather than "login:" and "ssword:" rather than
125 A very simple script might look like this:
127 ogin: ppp ssword: hello2u2
129 In other words, expect ....ogin:, send ppp, expect ...ssword:, send hello2u2.
131 In actual practice, simple scripts are rare. At the vary least, you
132 should include sub-expect sequences should the original string not be
133 received. For example, consider the following script:
135 ogin:--ogin: ppp ssword: hello2u2
137 This would be a better script than the simple one used earlier. This would look
138 for the same login: prompt, however, if one was not received, a single
139 return sequence is sent and then it will look for login: again. Should line
140 noise obscure the first login prompt then sending the empty line will
141 usually generate a login prompt again.
143 Comments can be embedded in the chat script. A comment is a line which
144 starts with the \fB#\fR (hash) character in column 1. Such comment
145 lines are just ignored by the chat program. If a '#' character is to
146 be expected as the first character of the expect sequence, you should
147 quote the expect string.
148 If you want to wait for a prompt that starts with a # (hash)
149 character, you would have to write something like this:
151 # Now wait for the prompt and send logout string
156 .SH SENDING DATA FROM A FILE
157 If the string to send starts with an at sign (@), the rest of the
158 string is taken to be the name of a file to read to get the string to
159 send. If the last character of the data read is a newline, it is
160 removed. The file can be a named pipe (or fifo) instead of a regular
161 file. This provides a way for \fBchat\fR to communicate with another
162 program, for example, a program to prompt the user and receive a
167 Many modems will report the status of the call as a string. These
168 strings may be \fBCONNECTED\fR or \fBNO CARRIER\fR or \fBBUSY\fR. It
169 is often desirable to terminate the script should the modem fail to
170 connect to the remote. The difficulty is that a script would not know
171 exactly which modem string it may receive. On one attempt, it may
172 receive \fBBUSY\fR while the next time it may receive \fBNO CARRIER\fR.
174 These "abort" strings may be specified in the script using the \fIABORT\fR
175 sequence. It is written in the script as in the following example:
177 ABORT BUSY ABORT 'NO CARRIER' '' ATZ OK ATDT5551212 CONNECT
179 This sequence will expect nothing; and then send the string ATZ. The
180 expected response to this is the string \fIOK\fR. When it receives \fIOK\fR,
181 the string ATDT5551212 to dial the telephone. The expected string is
182 \fICONNECT\fR. If the string \fICONNECT\fR is received the remainder of the
183 script is executed. However, should the modem find a busy telephone, it will
184 send the string \fIBUSY\fR. This will cause the string to match the abort
185 character sequence. The script will then fail because it found a match to
186 the abort string. If it received the string \fINO CARRIER\fR, it will abort
187 for the same reason. Either string may be received. Either string will
188 terminate the \fIchat\fR script.
189 .SH CLR_ABORT STRINGS
190 This sequence allows for clearing previously set \fBABORT\fR strings.
191 \fBABORT\fR strings are kept in an array of a pre-determined size (at
192 compilation time); \fBCLR_ABORT\fR will reclaim the space for cleared
193 entries so that new strings can use that space.
195 The \fBSAY\fR directive allows the script to send strings to the user
196 at the terminal via standard error. If \fBchat\fR is being run by
197 pppd, and pppd is running as a daemon (detached from its controlling
198 terminal), standard error will normally be redirected to the file
199 /etc/ppp/connect-errors.
201 \fBSAY\fR strings must be enclosed in single or double quotes. If
202 carriage return and line feed are needed in the string to be output,
203 you must explicitely add them to your string.
205 The SAY strings could be used to give progress messages in sections of
206 the script where you want to have 'ECHO OFF' but still let the user
207 know what is happening. An example is:
213 SAY "Dialling your ISP...\\n"
219 SAY "Waiting up to 2 minutes for connection ... "
223 SAY "Connected, now logging in ...\n"
230 SAY "Logged in OK ...\n"
233 This sequence will only present the SAY strings to the user and all
234 the details of the script will remain hidden. For example, if the
235 above script works, the user will see:
239 Waiting up to 2 minutes for connection ... Connected, now logging in ...
245 A \fBreport\fR string is similar to the ABORT string. The difference
246 is that the strings, and all characters to the next control character
247 such as a carriage return, are written to the report file.
249 The report strings may be used to isolate the transmission rate of the
250 modem's connect string and return the value to the chat user. The
251 analysis of the report string logic occurs in conjunction with the
252 other string processing such as looking for the expect string. The use
253 of the same string for a report and abort sequence is probably not
254 very useful, however, it is possible.
256 The report strings to no change the completion code of the program.
258 These "report" strings may be specified in the script using the \fIREPORT\fR
259 sequence. It is written in the script as in the following example:
261 REPORT CONNECT ABORT BUSY '' ATDT5551212 CONNECT '' ogin: account
263 This sequence will expect nothing; and then send the string
264 ATDT5551212 to dial the telephone. The expected string is
265 \fICONNECT\fR. If the string \fICONNECT\fR is received the remainder
266 of the script is executed. In addition the program will write to the
267 expect-file the string "CONNECT" plus any characters which follow it
268 such as the connection rate.
269 .SH CLR_REPORT STRINGS
270 This sequence allows for clearing previously set \fBREPORT\fR strings.
271 \fBREPORT\fR strings are kept in an array of a pre-determined size (at
272 compilation time); \fBCLR_REPORT\fR will reclaim the space for cleared
273 entries so that new strings can use that space.
275 The echo options controls whether the output from the modem is echoed
276 to \fIstderr\fR. This option may be set with the \fI-e\fR option, but
277 it can also be controlled by the \fIECHO\fR keyword. The "expect-send"
278 pair \fIECHO\fR \fION\fR enables echoing, and \fIECHO\fR \fIOFF\fR
279 disables it. With this keyword you can select which parts of the
280 conversation should be visible. For instance, with the following
299 all output resulting from modem configuration and dialing is not visible,
300 but starting with the \fICONNECT\fR (or \fIBUSY\fR) message, everything
303 The HANGUP options control whether a modem hangup should be considered
304 as an error or not. This option is useful in scripts for dialling
305 systems which will hang up and call your system back. The HANGUP
306 options can be \fBON\fR or \fBOFF\fR.
308 When HANGUP is set OFF and the modem hangs up (e.g., after the first
309 stage of logging in to a callback system), \fBchat\fR will continue
310 running the script (e.g., waiting for the incoming call and second
311 stage login prompt). As soon as the incoming call is connected, you
312 should use the \fBHANGUP ON\fR directive to reinstall normal hang up
313 signal behavior. Here is an (simple) example script:
325 \'Callback login:' call_back_ID
331 \'Callback Password:' Call_back_password
341 ogin:--BREAK--ogin: real_account
346 The initial timeout value is 45 seconds. This may be changed using the \fB-t\fR
349 To change the timeout value for the next expect string, the following
352 ATZ OK ATDT5551212 CONNECT TIMEOUT 10 ogin:--ogin: TIMEOUT 5 assword: hello2u2
354 This will change the timeout to 10 seconds when it expects the login:
355 prompt. The timeout is then changed to 5 seconds when it looks for the
358 The timeout, once changed, remains in effect until it is changed again.
360 The special reply string of \fIEOT\fR indicates that the chat program
361 should send an EOT character to the remote. This is normally the
362 End-of-file character sequence. A return character is not sent
365 The EOT sequence may be embedded into the send string using the
368 The special reply string of \fIBREAK\fR will cause a break condition
369 to be sent. The break is a special signal on the transmitter. The
370 normal processing on the receiver is to change the transmission rate.
371 It may be used to cycle through the available transmission rates on
372 the remote until you are able to receive a valid login prompt.
374 The break sequence may be embedded into the send string using the
377 The expect and reply strings may contain escape sequences. All of the
378 sequences are legal in the reply string. Many are legal in the expect.
379 Those which are not valid in the expect sequence are so indicated.
382 Expects or sends a null string. If you send a null string then it will still
383 send the return character. This sequence may either be a pair of apostrophe
387 represents a backspace character.
390 Suppresses the newline at the end of the reply string. This is the only
391 method to send a string without a trailing return character. It must
392 be at the end of the send string. For example,
393 the sequence hello\\c will simply send the characters h, e, l, l, o.
394 .I (not valid in expect.)
397 Delay for one second. The program uses sleep(1) which will delay to a
398 maximum of one second.
399 .I (not valid in expect.)
403 .I (not valid in expect.)
406 Send a newline or linefeed character.
409 Send a null character. The same sequence may be represented by \\0.
410 .I (not valid in expect.)
413 Pause for a fraction of a second. The delay is 1/10th of a second.
414 .I (not valid in expect.)
417 Suppress writing the string to the SYSLOG file. The string ?????? is
418 written to the log in its place.
419 .I (not valid in expect.)
422 Send or expect a carriage return.
425 Represents a space character in the string. This may be used when it
426 is not desirable to quote the strings which contains spaces. The
427 sequence 'HI TIM' and HI\\sTIM are the same.
430 Send or expect a tab character.
433 Send or expect a backslash character.
436 Collapse the octal digits (ddd) into a single ASCII character and send that
438 .I (some characters are not valid in expect.)
441 Substitute the sequence with the control character represented by C.
442 For example, the character DC1 (17) is shown as \^^Q.
443 .I (some characters are not valid in expect.)
444 .SH TERMINATION CODES
445 The \fIchat\fR program will terminate with the following completion
449 The normal termination of the program. This indicates that the script
450 was executed without error to the normal conclusion.
453 One or more of the parameters are invalid or an expect string was too
454 large for the internal buffers. This indicates that the program as not
458 An error occurred during the execution of the program. This may be due
459 to a read or write operation failing for some reason or chat receiving
460 a signal such as SIGINT.
463 A timeout event occurred when there was an \fIexpect\fR string without
464 having a "-subsend" string. This may mean that you did not program the
465 script correctly for the condition or that some unexpected event has
466 occurred and the expected string could not be found.
469 The first string marked as an \fIABORT\fR condition occurred.
472 The second string marked as an \fIABORT\fR condition occurred.
475 The third string marked as an \fIABORT\fR condition occurred.
478 The fourth string marked as an \fIABORT\fR condition occurred.
481 The other termination codes are also strings marked as an \fIABORT\fR
484 Using the termination code, it is possible to determine which event
485 terminated the script. It is possible to decide if the string "BUSY"
486 was received from the modem as opposed to "NO DIAL TONE". While the
487 first event may be retried, the second will probably have little
488 chance of succeeding during a retry.
490 Additional information about \fIchat\fR scripts may be found with UUCP
491 documentation. The \fIchat\fR script was taken from the ideas proposed
492 by the scripts used by the \fIuucico\fR program.
496 The \fIchat\fR program is in public domain. This is not the GNU public
497 license. If it breaks then you get to keep both pieces.
projects / ppp.git / blob