chat.8

经典的ppp程序

.LP
The report strings to no change the completion code of the program.
.LP
These "report" strings may be specified in the script using the \fIREPORT\fR
sequence. It is written in the script as in the following example:
.IP
REPORT CONNECT ABORT BUSY '' ATDT5551212 CONNECT '' ogin: account
.LP
This sequence will expect nothing; and then send the string
ATDT5551212 to dial the telephone. The expected string is
\fICONNECT\fR. If the string \fICONNECT\fR 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.
.SH CLR_REPORT STRINGS
This sequence allows for clearing previously set \fBREPORT\fR strings.
\fBREPORT\fR strings are kept in an array of a pre-determined size (at
compilation time); \fBCLR_REPORT\fR will reclaim the space for cleared
entries so that new strings can use that space.
.SH ECHO
The echo options controls whether the output from the modem is echoed
to \fIstderr\fR. This option may be set with the \fI-e\fR option, but
it can also be controlled by the \fIECHO\fR keyword. The "expect-send"
pair \fIECHO\fR \fION\fR enables echoing, and \fIECHO\fR \fIOFF\fR
disables it. With this keyword you can select which parts of the
conversation should be visible. For instance, with the following
script:
.IP
ABORT   'BUSY'
.br
ABORT   'NO CARRIER'
.br
''      ATZ
.br
OK\\r\\n  ATD1234567
.br
\\r\\n    \\c
.br
ECHO    ON
.br
CONNECT \\c
.br
ogin:   account
.LP
all output resulting from modem configuration and dialing is not visible,
but starting with the \fICONNECT\fR (or \fIBUSY\fR) message, everything
will be echoed.
.SH 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 \fBON\fR or \fBOFF\fR.
.br
When HANGUP is set OFF and the modem hangs up (e.g., after the first
stage of logging in to a callback system), \fBchat\fR 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 \fBHANGUP ON\fR directive to reinstall normal hang up
signal behavior.  Here is an (simple) example script:
.IP
ABORT   'BUSY'
.br
''      ATZ
.br
OK\\r\\n  ATD1234567
.br
\\r\\n    \\c
.br
CONNECT \\c
.br
\'Callback login:' call_back_ID
.br
HANGUP OFF
.br
ABORT "Bad Login"
.br
\'Callback Password:' Call_back_password
.br
TIMEOUT 120
.br
CONNECT \\c
.br
HANGUP ON
.br
ABORT "NO CARRIER"
.br
ogin:--BREAK--ogin: real_account
.br
\fIetc ...\fR
.LP
.SH TIMEOUT
The initial timeout value is 45 seconds. This may be changed using the \fB-t\fR
parameter.
.LP
To change the timeout value for the next expect string, the following
example may be used:
.IP
ATZ OK ATDT5551212 CONNECT TIMEOUT 10 ogin:--ogin: TIMEOUT 5 assword: hello2u2
.LP
This will change the timeout to 10 seconds when it expects the login:
prompt. The timeout is then changed to 5 seconds when it looks for the
password prompt.
.LP
The timeout, once changed, remains in effect until it is changed again.
.SH SENDING EOT
The special reply string of \fIEOT\fR indicates that the chat program
should send an EOT character to the remote. This is normally the
End-of-file character sequence. A return character is not sent
following the EOT.
.PR
The EOT sequence may be embedded into the send string using the
sequence \fI^D\fR.
.SH GENERATING BREAK
The special reply string of \fIBREAK\fR will cause a break condition
to be sent. The break is a special signal on the transmitter. The
normal processing on the receiver is to change the transmission rate.
It may be used to cycle through the available transmission rates on
the remote until you are able to receive a valid login prompt.
.PR
The break sequence may be embedded into the send string using the
\fI\\K\fR sequence.
.SH ESCAPE SEQUENCES
The expect and reply strings may contain escape sequences. All of the
sequences are legal in the reply string. Many are legal in the expect.
Those which are not valid in the expect sequence are so indicated.
.TP
.B ''
Expects or sends a null string. If you send a null string then it will still
send the return character. This sequence may either be a pair of apostrophe
or quote characters.
.TP
.B \\\\b
represents a backspace character.
.TP
.B \\\\c
Suppresses the newline at the end of the reply string. This is the only
method to send a string without a trailing return character. It must
be at the end of the send string. For example,
the sequence hello\\c will simply send the characters h, e, l, l, o.
.I (not valid in expect.)
.TP
.B \\\\d
Delay for one second. The program uses sleep(1) which will delay to a
maximum of one second.
.I (not valid in expect.)
.TP
.B \\\\K
Insert a BREAK
.I (not valid in expect.)
.TP
.B \\\\n
Send a newline or linefeed character.
.TP
.B \\\\N
Send a null character. The same sequence may be represented by \\0.
.I (not valid in expect.)
.TP
.B \\\\p
Pause for a fraction of a second. The delay is 1/10th of a second.
.I (not valid in expect.)
.TP
.B \\\\q
Suppress writing the string to the SYSLOG file. The string ?????? is
written to the log in its place.
.I (not valid in expect.)
.TP
.B \\\\r
Send or expect a carriage return.
.TP
.B \\\\s
Represents a space character in the string. This may be used when it
is not desirable to quote the strings which contains spaces. The
sequence 'HI TIM' and HI\\sTIM are the same.
.TP
.B \\\\t
Send or expect a tab character.
.TP
.B \\\\T
Send the phone number string as specified with the \fI-T\fR option
.I (not valid in expect.)
.TP
.B \\\\U
Send the phone number 2 string as specified with the \fI-U\fR option
.I (not valid in expect.)
.TP
.B \\\\\\\\
Send or expect a backslash character.
.TP
.B \\\\ddd
Collapse the octal digits (ddd) into a single ASCII character and send that
character.
.I (some characters are not valid in expect.)
.TP
.B \^^C
Substitute the sequence with the control character represented by C.
For example, the character DC1 (17) is shown as \^^Q.
.I (some characters are not valid in expect.)
.SH ENVIRONMENT VARIABLES
Environment variables are available within chat scripts, if  the \fI-E\fR
option was specified in the command line. The metacharacter \fI$\fR is used
to introduce the name of the environment variable to substitute. If the
substition fails, because the requested environment variable is not set,
\fInothing\fR is replaced for the variable.
.SH TERMINATION CODES
The \fIchat\fR program will terminate with the following completion
codes.
.TP
.B 0
The normal termination of the program. This indicates that the script
was executed without error to the normal conclusion.
.TP
.B 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.
.TP
.B 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.
.TP
.B 3
A timeout event occurred when there was an \fIexpect\fR 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.
.TP
.B 4
The first string marked as an \fIABORT\fR condition occurred.
.TP
.B 5
The second string marked as an \fIABORT\fR condition occurred.
.TP
.B 6
The third string marked as an \fIABORT\fR condition occurred.
.TP
.B 7
The fourth string marked as an \fIABORT\fR condition occurred.
.TP
.B ...
The other termination codes are also strings marked as an \fIABORT\fR
condition.
.LP
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.
.SH SEE ALSO
Additional information about \fIchat\fR scripts may be found with UUCP
documentation. The \fIchat\fR script was taken from the ideas proposed
by the scripts used by the \fIuucico\fR program.
.LP
uucico(1), uucp(1)
.SH COPYRIGHT
The \fIchat\fR program is in public domain. This is not the GNU public
license. If it breaks then you get to keep both pieces.