2 .\" manual page [] for chat 1.8
3 .\" $Id: chat.8,v 1.3 1995/12/18 03:32:45 paulus Exp $
5 .\" SS subsection heading
7 .\" IP indented paragraph
9 .TH CHAT 8 "5 May 1995" "Chat Version 1.9"
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 Request that the \fIchat\fR script be executed in a verbose mode. The
48 \fIchat\fR program will then log all text received from the modem and
49 the output strings which it sends to the SYSLOG.
52 Request that the \fIchat\fR script be executed in a stderr verbose
53 mode. The \fIchat\fR program will then log all text received from the
54 modem and the output strings which it sends to the stderr device. This
55 device is usually the local console at the station running the chat or
56 pppd program. This option will not work properly if the stderr is
57 redirected to the /dev/null locaiton as is the case should pppd be run
58 in the 'detached' mode. In that case, use the '-v' option to record
59 the session on the SYSLOG device.
62 If the script is not specified in a file with the \fI-f\fR option then
63 the script is included as parameters to the \fIchat\fR program.
66 The \fIchat\fR script defines the communications.
68 A script consists of one or more "expect-send" pairs of strings,
69 separated by spaces, with an optional "subexpect-subsend" string pair,
70 separated by a dash as in the following example:
72 ogin:-BREAK-ogin: ppp ssword: hello2u2
74 This line indicates that the \fIchat\fR program should expect the string
75 "ogin:". If it fails to receive a login prompt within the time interval
76 allotted, it is to send a break sequence to the remote and then expect the
77 string "ogin:". If the first "ogin:" is received then the break sequence is
80 Once it received the login prompt the \fIchat\fR program will send the
81 string ppp and then expect the prompt "ssword:". When it receives the
82 prompt for the password, it will send the password hello2u2.
84 A carriage return is normally sent following the reply string. It is not
85 expected in the "expect" string unless it is specifically requested by using
86 the \\r character sequence.
88 The expect sequence should contain only what is needed to identify the
89 string. Since it is normally stored on a disk file, it should not contain
90 variable information. It is generally not acceptable to look for time
91 strings, network identification strings, or other variable pieces of data as
94 To help correct for characters which may be corrupted during the initial
95 sequence, look for the string "ogin:" rather than "login:". It is possible
96 that the leading "l" character may be received in error and you may never
97 find the string even though it was sent by the system. For this reason,
98 scripts look for "ogin:" rather than "login:" and "ssword:" rather than
101 A very simple script might look like this:
103 ogin: ppp ssword: hello2u2
105 In other words, expect ....ogin:, send ppp, expect ...ssword:, send hello2u2.
107 In actual practice, simple scripts are rare. At the vary least, you
108 should include sub-expect sequences should the original string not be
109 received. For example, consider the following script:
111 ogin:--ogin: ppp ssowrd: hello2u2
113 This would be a better script than the simple one used earlier. This would look
114 for the same login: prompt, however, if one was not received, a single
115 return sequence is sent and then it will look for login: again. Should line
116 noise obscure the first login prompt then sending the empty line will
117 usually generate a login prompt again.
119 Many modems will report the status of the call as a string. These
120 strings may be \fBCONNECTED\fR or \fBNO CARRIER\fR or \fBBUSY\fR. It
121 is often desirable to terminate the script should the modem fail to
122 connect to the remote. The difficulty is that a script would not know
123 exactly which modem string it may receive. On one attempt, it may
124 receive \fBBUSY\fR while the next time it may receive \fBNO CARRIER\fR.
126 These "abort" strings may be specified in the script using the \fIABORT\fR
127 sequence. It is written in the script as in the following example:
129 ABORT BUSY ABORT 'NO CARRIER' '' ATZ OK ATDT5551212 CONNECT
131 This sequence will expect nothing; and then send the string ATZ. The
132 expected response to this is the string \fIOK\fR. When it receives \fIOK\fR,
133 the string ATDT5551212 to dial the telephone. The expected string is
134 \fICONNECT\fR. If the string \fICONNECT\fR is received the remainder of the
135 script is executed. However, should the modem find a busy telephone, it will
136 send the string \fIBUSY\fR. This will cause the string to match the abort
137 character sequence. The script will then fail because it found a match to
138 the abort string. If it received the string \fINO CARRIER\fR, it will abort
139 for the same reason. Either string may be received. Either string will
140 terminate the \fIchat\fR script.
143 A \fBreport\fR string is similar to the ABORT string. The difference
144 is that the strings, and all characters to the next control character
145 such as a carriage return, are written to the report file.
147 The report strings may be used to isolate the transmission rate of the
148 modem's connect string and return the value to the chat user. The
149 analysis of the report string logic occurs in conjunction with the
150 other string processing such as looking for the expect string. The use
151 of the same string for a report and abort sequence is probably not
152 very useful, however, it is possible.
154 The report strings to no change the completion code of the program.
156 These "report" strings may be specified in the script using the \fIREPORT\fR
157 sequence. It is written in the script as in the following example:
159 REPORT CONNECT ABORT BUSY '' ATDT5551212 CONNECT '' ogin: account
161 This sequence will expect nothing; and then send the string
162 ATDT5551212 to dial the telephone. The expected string is
163 \fICONNECT\fR. If the string \fICONNECT\fR is received the remainder
164 of the script is executed. In addition the program will write to the
165 expect-file the string "CONNECT" plus any characters which follow it
166 such as the connection rate.
168 The initial timeout value is 45 seconds. This may be changed using the \fB-t\fR
171 To change the timeout value for the next expect string, the following
174 ATZ OK ATDT5551212 CONNECT TIMEOUT 10 ogin:--ogin: TIMEOUT 5 assowrd: hello2u2
176 This will change the timeout to 10 seconds when it expects the login:
177 prompt. The timeout is then changed to 5 seconds when it looks for the
180 The timeout, once changed, remains in effect until it is changed again.
182 The special reply string of \fIEOT\fR indicates that the chat program
183 should send an EOT character to the remote. This is normally the
184 End-of-file character sequence. A return character is not sent
187 The EOT sequence may be embedded into the send string using the
190 The special reply string of \fIBREAK\fR will cause a break condition
191 to be sent. The break is a special signal on the transmitter. The
192 normal processing on the receiver is to change the transmission rate.
193 It may be used to cycle through the available transmission rates on
194 the remote until you are able to receive a valid login prompt.
196 The break sequence may be embedded into the send string using the
199 The expect and reply strings may contain escape sequences. All of the
200 sequences are legal in the reply string. Many are legal in the expect.
201 Those which are not valid in the expect sequence are so indicated.
204 Expects or sends a null string. If you send a null string then it will still
205 send the return character. This sequence may either be a pair of apostrophe
209 represents a backspace character.
212 Suppresses the newline at the end of the reply string. This is the only
213 method to send a string without a trailing return character. It must
214 be at the end of the send string. For example,
215 the sequence hello\\c will simply send the characters h, e, l, l, o.
216 .I (not valid in expect.)
219 Delay for one second. The program uses sleep(1) which will delay to a
220 maximum of one second.
221 .I (not valid in expect.)
225 .I (not valid in expect.)
228 Send a newline or linefeed character.
231 Send a null character. The same sequence may be represented by \\0.
232 .I (not valid in expect.)
235 Pause for a fraction of a second. The delay is 1/10th of a second.
236 .I (not valid in expect.)
239 Suppress writing the string to the SYSLOG file. The string ?????? is
240 written to the log in its place.
241 .I (not valid in expect.)
244 Send or expect a carriage return.
247 Represents a space character in the string. This may be used when it
248 is not desirable to quote the strings which contains spaces. The
249 sequence 'HI TIM' and HI\\sTIM are the same.
252 Send or expect a tab character.
255 Send or expect a backslash character.
258 Collapse the octal digits (ddd) into a single ASCII character and send that
260 .I (some characters are not valid in expect.)
263 Substitute the sequence with the control character represented by C.
264 For example, the character DC1 (17) is shown as \^^Q.
265 .I (some characters are not valid in expect.)
266 .SH TERMINATION CODES
267 The \fIchat\fR program will terminate with the following completion
271 The normal termination of the program. This indicates that the script
272 was executed without error to the normal conclusion.
275 One or more of the parameters are invalid or an expect string was too
276 large for the internal buffers. This indicates that the program as not
280 An error occurred during the execution of the program. This may be due
281 to a read or write operation failing for some reason or chat receiving
282 a signal such as SIGINT.
285 A timeout event occurred when there was an \fIexpect\fR string without
286 having a "-subsend" string. This may mean that you did not program the
287 script correctly for the condition or that some unexpected event has
288 occurred and the expected string could not be found.
291 The first string marked as an \fIABORT\fR condition occurred.
294 The second string marked as an \fIABORT\fR condition occurred.
297 The third string marked as an \fIABORT\fR condition occurred.
300 The fourth string marked as an \fIABORT\fR condition occurred.
303 The other termination codes are also strings marked as an \fIABORT\fR
306 Using the termination code, it is possible to determine which event
307 terminated the script. It is possible to decide if the string "BUSY"
308 was received from the modem as opposed to "NO DIAL TONE". While the
309 first event may be retried, the second will probably have little
310 chance of succeeding during a retry.
312 Additional information about \fIchat\fR scripts may be found with UUCP
313 documentation. The \fIchat\fR script was taken from the ideas proposed
314 by the scripts used by the \fIuucico\fR program.
318 The \fIchat\fR program is in public domain. This is not the GNU public
319 license. If it breaks then you get to keep both pieces.
projects / ppp.git / blob