CHAT(8)

NAME
chat - □□□□自□□通的指令稿

總覽 SYNOPSIS
chat [ options ] script

描述 DESCRIPTION

chat 程式在□□□□□□之□定□□通交□事宜。 它最主要的 目的是用□在□□□□定的□形程式 (pppd) 以及□端的 pppd 程式 之□建立□□。

選項 OPTIONS

-f <chat file>
    □ chat □案□取 chat 指令稿。□□□□的使用□ chat 的 令稿□□互斥(mutually exclusive)。使用者必□具有存取□ □案的□取□。在□案中允□多□(multiple lines)□定。□ □要以空白或是□向定位(horizontal tab)字元□分隔字串。

-t <timeout>
    □於所要接收的期待字串(expected string)□定逾□限制。 如果在□□□限制□□有接收到□字串的□那□就不送出回覆 字串(reply string)。 可以送出一□□通(alternate)的回覆 或者如果□有□通的回覆字串□□指令稿□□失□。一□失□ 的指令稿□□使得 chat 程式以一□非零的□□□□束。

-r <report file>
    Set the file for output of the report strings. If you use the keyword REPORT, the resulting strings are written to this file. If this option is not used and you still use REPORT keywords, the stderr file is used for the report strings.

-e  Start with the echo option turned on. Echoing may also be turned on or off at specific points in the chat script by using the ECHO keyword. When echoing is enabled, all output from the modem is echoed to stderr.

-E  Enables environment variable substituion within chat scripts using the standard $xxx syntax.

-v  要求 chat 指令稿以冗□(verbose)模式□行。 □□ chat 程 式接下□□□所有□□□□接收的文字以及□出的字串□□到 SYSLOG 去。The default is to log through the SYSLOG; the logging method may be altered with the -S and -s flags.

-V  Request that the chat script be executed in a stderr verbose mode. The chat program will then log all text received from the modem and the output strings sent to the modem to the stderr device. This device is usually the local console at the station running the chat or pppd program.

-s  Use stderr. All log messages from '-v' and all error messages will be sent to stderr.

-S  Do not use the SYSLOG. By default, error messages are sent to the SYSLOG. The use of -S will prevent both log messages from '-v' and error messages from being sent to the SYSLOG.

-T <phone number>
    Pass in an arbitary string, usually a phone number, that will be substituted for the \T substitution metacharacter in a send string.

-U <phone number 2>
    Pass in a second string, usually a phone number, that will be substituted for the \U substitution metacharacter in a send string. This is useful when dialing an ISDN terminal adapter that requires two numbers.

script
    script 如果指令稿□有以 -f □□指定在□案□那□□指令稿□如同 □□般被包含在 chat 程式□。

CHAT 稿本 SCRIPT

chat 稿本定□通□□程

一□指令稿□包含一□或多□□期待□方送出(expect-send)□的配□ 字串(pairs of string)，以空白隔□，□有一□□□性的□期待□方 送出之候□(subexpect-subsend)□配□字串，以短□(dash)隔□。像 下面□□例子：

    ogin:-BREAK-ogin: ppp ssword: hello2u2

□一行指示 chat 程式□□期待 "ogin:" □□字串。如果在所分配的 □□□□□接收□入提示失□的□， 那它就送出一□中□程式(break sequence)□□端然後期待 "ogin:" □□字串。 如果第一□ "ogin:" 被接收到那□中□程式就不□□生。

一旦它接收到□□入提示□ chat 程式□□送出 ppp □□字串然後期 待 "ssword:" □□提示。□它接收到密□提示以後，它□□送出密□ hello2u2 。

一般在回覆字串後面□跟著送出一□□架返回(carriage return)。在 □期待□字串□除非以 字元程式(character sequence)指定□必 □否□不□期待它的出□。

期待程式(expect sequence)□□只包含辨□字串所需要的□料。因□ 它一般是□放在磁碟□案□，它不□□包含□□的□□。 通常以期待 字串□□找□□字串(time strings)， □路辨□字串(network iden- tification strings)，或是其它□□的□料是不被接受的。

□求□助修正在初始化程式中(initial sequence) 可能□□送□□的 字元，所以□找 "ogin:" □□字串而不是 "login:" 。 □□的 "l" 字元可能接收□□而你永□找不到□字串， 即使它已□被系□送出。 因此□故，指令稿□找 "ogin:" 而不是 "login:" 以及 "ssword" 而 不是 "password:" 。

一□非常□□的指令稿看起□可能像□□：

    ogin: ppp ssword: hello2u2

□句□□， 期待 ...ogin:, 送出 ppp, 期待 ...ssword:, 再送出 hello2u2 。

在□□使用上，□□的指令稿是罕□的。最少最少， 原先的字串□有 被接收□你□□要把候□期待(sub-sequences)包括□□。例如，考□ 下面□□例子：

    ogin:--ogin: ppp ssword: hello2u2

□□是一□比前面所用的□□指令稿更好的指令稿。 □□□□找相同 同的 login: 提示，然而, 如果□有接收到的□， □送出一□□□的 返回程式(return sequence)□且它□接著再次□找 login: 。要是□ □□掩□掉第一□ login 提示那□接著送出空□路(empty line)□常 □□再次□生□入提示。

COMMENTS
Comments can be embedded in the chat script. A comment is a line which starts with the # (hash) character in column 1. Such comment lines are just ignored by the chat program. If a '#' character is to be expected as the first character of the expect sequence, you should quote the expect string. If you want to wait for a prompt that starts with a # (hash) character, you would have to write something like this:

    # Now wait for the prompt and send logout string
    '# ' logout

SENDING DATA FROM A FILE
If the string to send starts with an at sign (@), the rest of the string is taken to be the name of a file to read to get the string to send. If the last character of the data read is a newline, it is removed. The file can be a named pipe (or fifo) instead of a regular file. This provides a way for chat to communicate with another program, for example, a program to prompt the user and receive a password typed in.

放棄字符串 ABORT STRINGS
□多□□□□以字串□回□呼叫的□□。 □些字串可能是 CONNECTED 或是 NO CARRIER 或是 BUSY 。 通常要是□□□□□到□端失□的□ □□□希望□束指令稿。 困□是指令稿不□□□地知道它可能接收到 哪□□□□字串。在某次□□□， 他可能接收到 BUSY 然而下次它可 能接收到 NO CARRIER 。

□些□失□□字串可以用 ABORT 程式指定到指令稿中。像是下面□□ 例子般地□到指令稿□：

    ABORT BUSY ABORT 'NO CARRIER' '' ATZ OK ATDT5551212 CONNECT

□□程式□不□期待什□；而且接著送出 ATZ □□字串。□此期待的 回□是 OK □□字串。□它接收到 OK □，字串 ADTD5551212 就□行 □□。期待字串是 CONNECT 。 如果字串 CONNECT 被接收到那□就□ □行指令稿其□的部份。然而，要是□□□□□□□忙□， 他□□送 出 BUSY □□字串。 □□使得□字串符合失□字元程式(abort char- acter)。 □□指令稿□□因□它□□一□失□字串(abort string)而 失□(fail)。如果他接收到的是 NO CARRIER 字串， 它也□因□同□ 的原因而失□。不是可以接收到字串就是字串□□□ chat 指令稿。

CLR_ABORT STRINGS
This sequence allows for clearing previously set ABORT strings. ABORT strings are kept in an array of a pre-determined size (at compilation time); CLR_ABORT will reclaim the space for cleared entries so that new strings can use that space.

SAY STRINGS
The SAY directive allows the script to send strings to the user at the terminal via standard error. If chat is being run by pppd, and pppd is running as a daemon (detached from its controlling terminal), standard error will normally be redirected to the file /etc/ppp/connect-errors.

SAY strings must be enclosed in single or double quotes. If carriage return and line feed are needed in the string to be output, you must explicitely add them to your string.

The SAY strings could be used to give progress messages in sections of the script where you want to have 'ECHO OFF' but still let the user know what is happening. An example is:

    ABORT BUSY
    ECHO OFF
    SAY "Dialling your ISP...\n"
    '' ATDT5551212
    TIMEOUT 120
    SAY "Waiting up to 2 minutes for connection ... "
    CONNECT ''
    SAY "Connected, now logging in ...
    ogin: account
    ssword: pass
    $ SAY "Logged in OK ... etc ...

This sequence will only present the SAY strings to the user and all the details of the script will remain hidden. For example, if the above script works, the user will see:

    Dialling your ISP...
    Waiting up to 2 minutes for connection ... Connected, now logging in ...
    Logged in OK ...

REPORT STRINGS
A report string is similar to the ABORT string. The difference is that the strings, and all characters to the next control character such as a carriage return, are written to the report file.

The report strings may be used to isolate the transmission rate of the modem's connect string and return the value to the chat user. The analysis of the report string logic occurs in conjunction with the other string processing such as looking for the expect string. The use of the same string for a report and abort sequence is probably not very useful, however, it is possible.

The report strings to no change the completion code of the program.

These "report" strings may be specified in the script using the REPORT sequence. It is written in the script as in the following example:

    REPORT CONNECT ABORT BUSY '' ATDT5551212 CONNECT '' ogin: account

This sequence will expect nothing; and then send the string ATDT5551212 to dial the telephone. The expected string is CONNECT. If the string CONNECT is received the remainder of the script is executed. In addition the program will write to the expect-file the string "CONNECT" plus any characters which follow it such as the connection rate.

CLR_REPORT STRINGS
This sequence allows for clearing previously set REPORT strings. REPORT strings are kept in an array of a pre-determined size (at compilation time); CLR_REPORT will reclaim the space for cleared entries so that new strings can use that space.

ECHO
The echo options controls whether the output from the modem is echoed to stderr. This option may be set with the -e option, but it can also be controlled by the ECHO keyword. The "expect-send" pair ECHO ON enables echoing, and ECHO OFF disables it. With this keyword you can select which parts of the conversation should be visible. For instance, with the following script:

    ABORT 'BUSY'
    ABORT 'NO CARRIER'
     ''
    ATZ
    OK\r\n ATD1234567
    \r\n \c
    ECHO ON
    CONNECT \c
    ogin: account

all output resulting from modem configuration and dialing is not visible, but starting with the CONNECT (or BUSY) message, everything will be echoed.

HANGUP
The HANGUP options control whether a modem hangup should be considered as an error or not. This option is useful in scripts for dialling systems which will hang up and call your system back. The HANGUP options can be ON or OFF.
When HANGUP is set OFF and the modem hangs up (e.g., after the first stage of logging in to a callback system), chat will continue running the script (e.g., waiting for the incoming call and second stage login prompt). As soon as the incoming call is connected, you should use the HANGUP ON directive to reinstall normal hang up signal behavior. Here is an (simple) example script:

    ABORT 'BUSY'
    '' ATZ
    OK\r\n ATD1234567
    \r\n \c
    CONNECT \c
    'Callback login:' call_back_ID
    HANGUP OFF
    ABORT "Bad Login"
    'Callback Password:' Call_back_password
    TIMEOUT 120
    CONNECT \c
    HANGUP ON
    ABORT "NO CARRIER"
    ogin:--BREAK--ogin: real_account
    etc ...

超時 TIMEOUT
初始的逾□值是 45 秒。□可以用 -t □□□加以改□。

要□下一□期待字串改□逾□值的□，可以使用下面□□例子：

    ATZ OK ATDT5551212 CONNECT TIMEOUT 10 ogin:--ogin: TIMEOUT 5 assword: hello2u2

□□□在期待 "login:" 提示的□候把逾□限制改成 10 秒。 逾□限 制接著在它□找密□提示□被改成 5 秒。

逾□限制一旦改□就□持□作用直到它再度被改□。

SENDING 發送 EOT
EOT □□特□的回覆字串指示 chat 程式□□送出一□ EOT 字元到□ 端去。□是一般的□案□束(End-of-file)字元程式。 在 EOT 後面□ 不□跟著送出一□返回字元(return)。

□□ EOT 程式可以用 ^D 序列嵌入到送出的字串□。

□生中□ GENERATING BREAK
BREAK □□特□的回覆字串□□使得一□中□情□被送出。 □□中□ 是□送端的一□特殊。接收端一般□此的□理是改□□□率。 它可以 用□循□□□□端可能的□□率直到你能□接到有效的□入提示。

□□中□程式可以用 \K 序列嵌入到送出的字串□。

轉義序列 ESCAPE SEQUENCES
期待以及回覆字串可以包含轉義序列。 所有□□程式在回覆字串中都 是合法的。有□多在期待字串中是合法的。 那些在期待程式中□效的 □被指出。

''  期待或送出一□空字串(null string) 。如果你送出一□空字 串那□它□□送出一□返回字元。□□程式可以是一□省略符 □(apostrophe)或者也可以是引用字元。

\\b 代表一□退位(backspace)字元。

\\c 抑制在回覆字串□尾的新列(newline)字元。 □是送出□有返 回字元尾□的字串的唯一方法。它必□在送出字串的□尾。例 如，□□程式 hello

\\d 延□一秒□。□程式使用最□延□□一秒的 sleep(1) 。（在 期待字串中□效。）

\\K 插入一□中□（在期待字串中□效。）

\\n 送出一□新列(newline)或□行(linefeed)字元。

\\N 送出一□空字元(null character)。同□的程式可以用 代 替。（在期待字串中□效。）

\\p □停一小段□□。延□ 1/10 秒。（在期待字串中□效。）

\\q 抑制字串□往 SYSLOG □案。□ ?????? 字串被□□到自己的 空□。（在期待字串中□效。）

\\r □送或期待一□□架返回（字元）

\\s 代替字串中的空白。□□可以用在不□引用包含空白的字串之□。'HI TIM' 以及 HI\sTIM 是相同的。

\\t □送或期待一□定位(tab)字元。

\\T Send the phone number string as specified with the -T option (not valid in expect.)

\\U Send the phone number 2 string as specified with the -U option (not valid in expect.)

\\\\
    □送或期待一□倒斜□(backslash)字元。

\\ddd
    □八□位□字 (ddd) 折□(collapse)成□一的 ASCII 字元□ □其送出。（某些字元在期待字串中□效。）

^C  替□含有以 C 代表之控制字元的程式。例如，字元 DC1(17) 是以 ^Q 表示。（某些字元在期待字串中□效。）

ENVIRONMENT VARIABLES
Environment variables are available within chat scripts, if the -E option was specified in the command line. The metacharacter $ is used to introduce the name of the environment variable to substitute. If the substition fails, because the requested environment variable is not set, nothing is replaced for the variable.

TERMINATION CODES
The chat program will terminate with the following completion codes.

0   The normal termination of the program. This indicates that the script was executed without error to the normal conclusion.

1   One or more of the parameters are invalid or an expect string was too large for the internal buffers. This indicates that the program as not properly executed.

2   An error occurred during the execution of the program. This may be due to a read or write operation failing for some reason or chat receiving a signal such as SIGINT.

3   A timeout event occurred when there was an expect string without having a "-subsend" string. This may mean that you did not program the script correctly for the condition or that some unexpected event has occurred and the expected string could not be found.

4   The first string marked as an ABORT condition occurred.

5   The second string marked as an ABORT condition occurred.

6   The third string marked as an ABORT condition occurred.

7   The fourth string marked as an ABORT condition occurred.

... The other termination codes are also strings marked as an ABORT condition.

Using the termination code, it is possible to determine which event terminated the script. It is possible to decide if the string "BUSY" was received from the modem as opposed to "NO DIAL TONE". While the first event may be retried, the second will probably have little chance of succeeding during a retry.

參見 SEE ALSO
□於 chat 指令稿的其它□□可以在 UUCP 檔案□找到。chat 指令稿 的概念由 uucico 程式所使用的指令稿□的。

uucico(1), uucp(1)

COPYRIGHT
The chat program is in public domain. This is not the GNU public license. If it breaks then you get to keep both pieces.

[中文版維護人]
asdchen <asdchen@pc2.hinet.net>

[中文版最新更新]
1995/09/30

《中國linux論壇man手冊翻譯計劃》:
http://cmpp.linuxforum.net