645 lines
17 KiB
Groff
645 lines
17 KiB
Groff
.\" $FreeBSD$
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.Dd September 10, 2012
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.Dt CHAT 8
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.Os
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.Sh NAME
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.Nm chat
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.Nd Automated conversational script with a modem
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.Sh SYNOPSIS
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.Nm
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.Op Fl eSsVv
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.Op Fl f Ar chat-file
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.Op Fl r Ar report-file
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.Op Fl T Ar phone-number
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.Op Fl t Ar timeout
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.Op Fl U Ar phone-number2
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.Op Ar script
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.Sh DESCRIPTION
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The
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.Nm
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program defines a conversational exchange between the
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computer and the modem.
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Its primary purpose is to establish the
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connection between the Point-to-Point Protocol Daemon
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.Pq pppd
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and the remote's pppd process.
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.Sh OPTIONS
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.Bl -tag -width indent
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.It Fl e
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Start with the echo option turned on.
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Echoing may also be turned on
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or off at specific points in the chat script by using the ECHO
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keyword.
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When echoing is enabled, all output from the modem is echoed
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to
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.Em stderr .
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.It Fl f Ar chat-file
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Read the chat script from the chat file.
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The use of this option
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is mutually exclusive with the chat script parameters.
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The user must
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have read access to the file.
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Multiple lines are permitted in the file.
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Space or horizontal tab characters should be used to separate
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the strings.
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.It Fl r Ar report-file
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Set the file for output of the report strings.
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If you use the keyword
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.Dv REPORT ,
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the resulting strings are written to this file.
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If this
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option is not used and you still use
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.Dv REPORT
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keywords, the
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.Pa stderr
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file is used for the report strings.
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.It Fl S
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Do not use
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.Xr syslog 3 .
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By default, error messages are sent to
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.Xr syslog 3 .
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The use of
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.Fl S
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will prevent both log messages from
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.Fl v
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and error messages from being sent to
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.Xr syslog 3 .
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.It Fl s
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Use
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.Em stderr .
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All log messages from
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.Fl v
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and all error messages will be
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sent to
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.Em stderr .
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.It Fl T Ar phone-number
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Pass in an arbitrary string, usually a phone number, that will be
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substituted for the \\T substitution metacharacter in a send string.
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.It Fl t Ar timeout
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Set the timeout for the expected string to be received.
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If the string
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is not received within the time limit then the reply string is not
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sent.
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An alternate reply may be sent or the script will fail if there
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is no alternate reply string.
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A failed script will cause the
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.Nm
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program to terminate with a non-zero error code.
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.It Fl U Ar phone-number2
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Pass in a second string, usually a phone number, that will be
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substituted for the \\U substitution metacharacter in a send string.
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This is useful when dialing an ISDN terminal adapter that requires two
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numbers.
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.It Fl V
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Request that the
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.Nm
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script be executed in a
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.Em stderr
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verbose mode.
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The
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.Nm
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program will then log all text received from the
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modem and the output strings sent to the modem to the stderr device.
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This
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device is usually the local console at the station running the chat or
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pppd program.
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.It Fl v
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Request that the
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.Nm
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script be executed in a verbose mode.
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The
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.Nm
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program will then log the execution state of the chat
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script as well as all text received from the modem and the output
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strings sent to the modem.
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The default is to log through
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.Xr syslog 3 ;
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the logging method may be altered with the
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.Fl S
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and
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.Fl s
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flags.
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Logging is done to the
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.Em local2
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facility at level
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.Em info
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for verbose tracing and level
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.Em err
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for some errors.
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.El
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.Sh CHAT SCRIPT
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The
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.Nm
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script defines the communications.
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A script consists of one or more "expect-send" pairs of strings,
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separated by spaces, with an optional "subexpect-subsend" string pair,
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separated by a dash as in the following example:
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.Pp
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.D1 ogin:-BREAK-ogin: ppp ssword: hello2u2
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.Pp
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This line indicates that the
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.Nm
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program should expect the string "ogin:".
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If it fails to receive a login prompt within the time interval
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allotted, it is to send a break sequence to the remote and then expect the
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string "ogin:".
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If the first "ogin:" is received then the break sequence is
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not generated.
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.Pp
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Once it received the login prompt the
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.Nm
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program will send the
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string ppp and then expect the prompt "ssword:".
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When it receives the
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prompt for the password, it will send the password hello2u2.
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.Pp
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A carriage return is normally sent following the reply string.
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It is not
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expected in the "expect" string unless it is specifically requested by using
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the \\r character sequence.
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.Pp
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The expect sequence should contain only what is needed to identify the
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string.
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Since it is normally stored on a disk file, it should not contain
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variable information.
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It is generally not acceptable to look for time
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strings, network identification strings, or other variable pieces of data as
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an expect string.
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.Pp
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To help correct for characters which may be corrupted during the initial
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sequence, look for the string "ogin:" rather than "login:".
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It is possible
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that the leading "l" character may be received in error and you may never
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find the string even though it was sent by the system.
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For this reason,
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scripts look for "ogin:" rather than "login:" and "ssword:" rather than
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"password:".
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.Pp
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A very simple script might look like this:
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.Pp
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.D1 ogin: ppp ssword: hello2u2
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.Pp
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In other words, expect ....ogin:, send ppp, expect ...ssword:, send hello2u2.
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.Pp
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In actual practice, simple scripts are rare.
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At the vary least, you
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should include sub-expect sequences should the original string not be
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received.
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For example, consider the following script:
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.Pp
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.D1 ogin:--ogin: ppp ssword: hello2u2
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.Pp
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This would be a better script than the simple one used earlier.
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This would look
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for the same login: prompt, however, if one was not received, a single
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return sequence is sent and then it will look for login: again.
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Should line
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noise obscure the first login prompt then sending the empty line will
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usually generate a login prompt again.
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.Sh COMMENTS
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Comments can be embedded in the chat script.
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A comment is a line which
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starts with the # (hash) character in column 1.
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Such comment
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lines are just ignored by the chat program.
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If a '#' character is to
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be expected as the first character of the expect sequence, you should
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quote the expect string.
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If you want to wait for a prompt that starts with a # (hash)
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character, you would have to write something like this:
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.Bd -literal -offset indent
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# Now wait for the prompt and send logout string
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\&'# ' logout
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.Ed
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.Sh ABORT STRINGS
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Many modems will report the status of the call as a string.
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These strings may be
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.Dv CONNECTED
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or
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.Dv NO CARRIER
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or
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.Dv BUSY .
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It is often desirable to terminate the script should the modem fail to
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connect to the remote.
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The difficulty is that a script would not know
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exactly which modem string it may receive.
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On one attempt, it may receive
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.Dv BUSY
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while the next time it may receive
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.Dv NO CARRIER .
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.Pp
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These "abort" strings may be specified in the script using the ABORT
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sequence.
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It is written in the script as in the following example:
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.Pp
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.D1 ABORT BUSY ABORT 'NO CARRIER' '' ATZ OK ATDT5551212 CONNECT
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.Pp
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This sequence will expect nothing; and then send the string ATZ.
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The expected response to this is the string
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.Dv OK .
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When it receives
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.Dv OK ,
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the string ATDT5551212 to dial the telephone.
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The expected string is
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.Dv CONNECT .
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If the string
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.Dv CONNECT
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is received the remainder of the
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script is executed.
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However, should the modem find a busy telephone, it will
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send the string
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.Dv BUSY .
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This will cause the string to match the abort
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character sequence.
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The script will then fail because it found a match to
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the abort string.
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If it received the string
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.Dv NO CARRIER ,
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it will abort
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for the same reason.
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Either string may be received.
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Either string will
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terminate the
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.Nm
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script.
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.Sh CLR_ABORT STRINGS
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This sequence allows for clearing previously set
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.Dv ABORT
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strings.
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.Dv ABORT
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strings are kept in an array of a pre-determined size (at
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compilation time); CLR_ABORT will reclaim the space for cleared
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entries so that new strings can use that space.
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.Sh SAY STRINGS
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The
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.Dv SAY
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directive allows the script to send strings to the user
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at the terminal via standard error.
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If
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.Nm
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is being run by
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pppd, and pppd is running as a daemon (detached from its controlling
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terminal), standard error will normally be redirected to the file
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.Pa /etc/ppp/connect-errors .
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.Pp
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.Dv SAY
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strings must be enclosed in single or double quotes.
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If carriage return and line feed are needed in the string to be output,
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you must explicitly add them to your string.
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.Pp
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The
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.Dv SAY
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strings could be used to give progress messages in sections of
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the script where you want to have 'ECHO OFF' but still let the user
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know what is happening. An example is:
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.Bd -literal -offset indent
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ABORT BUSY
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ECHO OFF
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SAY "Dialling your ISP...\\n"
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\&'' ATDT5551212
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TIMEOUT 120
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SAY "Waiting up to 2 minutes for connection ... "
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CONNECT ''
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SAY "Connected, now logging in ...\\n"
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ogin: account
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ssword: pass
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$ SAY "Logged in OK ...\\n" \fIetc ...\fR
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.Ed
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.Pp
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This sequence will only present the
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.Dv SAY
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strings to the user and all
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the details of the script will remain hidden.
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For example, if the
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above script works, the user will see:
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.Bd -literal -offset indent
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Dialling your ISP...
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Waiting up to 2 minutes for connection ... Connected, now logging in ...
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Logged in OK ...
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.Ed
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.Sh REPORT STRINGS
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A report string is similar to the
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.Dv ABORT
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string.
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The difference
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is that the strings, and all characters to the next control character
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such as a carriage return, are written to the report file.
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.Pp
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The report strings may be used to isolate the transmission rate of the
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modem's connect string and return the value to the chat user.
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The
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analysis of the report string logic occurs in conjunction with the
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other string processing such as looking for the expect string.
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The use
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of the same string for a report and abort sequence is probably not
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very useful, however, it is possible.
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.Pp
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The report strings to no change the completion code of the program.
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.Pp
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These "report" strings may be specified in the script using the
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.Dv REPORT
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sequence.
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It is written in the script as in the following example:
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.Pp
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.D1 REPORT CONNECT ABORT BUSY '' ATDT5551212 CONNECT '' ogin: account
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.Pp
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This sequence will expect nothing; and then send the string
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ATDT5551212 to dial the telephone.
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The expected string is
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.Dv CONNECT .
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If the string
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.Dv CONNECT
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is received the remainder
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of the script is executed.
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In addition the program will write to the
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expect-file the string "CONNECT" plus any characters which follow it
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such as the connection rate.
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.Sh CLR_REPORT STRINGS
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This sequence allows for clearing previously set
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.Dv REPORT
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strings.
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.Dv REPORT
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strings are kept in an array of a pre-determined size (at
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compilation time); CLR_REPORT will reclaim the space for cleared
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entries so that new strings can use that space.
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.Sh ECHO
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The echo options controls whether the output from the modem is echoed
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to
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.Em stderr .
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This option may be set with the
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.Fl e
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option, but
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it can also be controlled by the
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.Dv ECHO
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keyword.
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The "expect-send"
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pair
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.Dv ECHO ON
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enables echoing, and
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.Dv ECHO OFF
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disables it.
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With this keyword you can select which parts of the
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conversation should be visible.
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For instance, with the following
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script:
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.Bd -literal -offset indent
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ABORT 'BUSY'
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ABORT 'NO CARRIER'
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\&'' ATZ
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OK\\r\\n ATD1234567
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\\r\\n \\c
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ECHO ON
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CONNECT \\c
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ogin: account
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.Ed
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.Pp
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all output resulting from modem configuration and dialing is not visible,
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but starting with the
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.Dv CONNECT
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or
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.Dv BUSY
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message, everything
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will be echoed.
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.Sh HANGUP
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The
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.Dv HANGUP
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options control whether a modem hangup should be considered
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as an error or not.
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This option is useful in scripts for dialling
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systems which will hang up and call your system back.
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The
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.Dv HANGUP
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options can be
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.Dv ON
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or
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.Dv OFF .
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.Pp
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When
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.Dv HANGUP
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is set
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.Dv OFF
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and the modem hangs up (e.g., after the first
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stage of logging in to a callback system),
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.Nm
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will continue
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running the script (e.g., waiting for the incoming call and second
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stage login prompt).
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As soon as the incoming call is connected, you
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should use the
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.Dv HANGUP ON
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directive to reinstall normal hang up
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signal behavior.
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Here is a (simple) example script:
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.Bd -literal -offset indent
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ABORT 'BUSY'
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\&'' ATZ
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OK\\r\\n ATD1234567
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\\r\\n \\c
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CONNECT \\c
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\&'Callback login:' call_back_ID
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HANGUP OFF
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ABORT "Bad Login"
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\&'Callback Password:' Call_back_password
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TIMEOUT 120
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CONNECT \\c
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HANGUP ON
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ABORT "NO CARRIER"
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ogin:--BREAK--ogin: real_account
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\fIetc ...\fR
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.Ed
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.Sh TIMEOUT
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The initial timeout value is 45 seconds.
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This may be changed using the
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.Fl t
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parameter.
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.Pp
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To change the timeout value for the next expect string, the following
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example may be used:
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.Bd -literal -offset indent
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ATZ OK ATDT5551212 CONNECT TIMEOUT 10 ogin:--ogin: TIMEOUT 5 assword: hello2u2
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.Ed
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.Pp
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This will change the timeout to 10 seconds when it expects the login:
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prompt.
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The timeout is then changed to 5 seconds when it looks for the
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password prompt.
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.Pp
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The timeout, once changed, remains in effect until it is changed again.
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.Sh SENDING EOT
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The special reply string of
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.Dv EOT
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indicates that the chat program
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should send an
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.Dv EOT
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character to the remote.
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This is normally the
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End-of-file character sequence.
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A return character is not sent
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following the
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.Dv EOT .
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.Pp
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The
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.Dv EOT
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sequence may be embedded into the send string using the
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sequence ^D.
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.Sh GENERATING BREAK
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The special reply string of
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.Dv BREAK
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will cause a break condition
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to be sent.
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The break is a special signal on the transmitter.
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The
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normal processing on the receiver is to change the transmission rate.
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It may be used to cycle through the available transmission rates on
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the remote until you are able to receive a valid login prompt.
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.Pp
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The break sequence may be embedded into the send string using the
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\fI\\K\fR sequence.
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.Sh ESCAPE SEQUENCES
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The expect and reply strings may contain escape sequences.
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All of the
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sequences are legal in the reply string.
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Many are legal in the expect.
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Those which are not valid in the expect sequence are so indicated.
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.Bl -tag -width indent
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.It ''
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Expects or sends a null string.
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If you send a null string then it will still
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send the return character.
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This sequence may either be a pair of apostrophe
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or quote characters.
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.It \eb
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represents a backspace character.
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.It \ec
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Suppresses the newline at the end of the reply string.
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This is the only
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method to send a string without a trailing return character.
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It must
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be at the end of the send string.
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For example,
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the sequence hello\\c will simply send the characters h, e, l, l, o
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.Pq Em not valid in expect .
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.It \ed
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Delay for one second.
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The program uses sleep(1) which will delay to a
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maximum of one second
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.Pq Em not valid in expect .
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.It \eK
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Insert a
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.Dv BREAK
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.Pq Em not valid in expect .
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.It \en
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Send a newline or linefeed character.
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.It \eN
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Send a null character.
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The same sequence may be represented by \\0
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.Pq Em not valid in expect .
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.It \ep
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Pause for a fraction of a second.
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The delay is 1/10th of a second
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.Pq Em not valid in expect .
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.It \eq
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Suppress writing the string to
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.Xr syslogd 8 .
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The string ?????? is
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written to the log in its place
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.Pq Em not valid in expect .
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.It \er
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Send or expect a carriage return.
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.It \es
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Represents a space character in the string.
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|
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.
|
|
.It \et
|
|
Send or expect a tab character.
|
|
.It \e
|
|
Send or expect a backslash character.
|
|
.It \eddd
|
|
Collapse the octal digits (ddd) into a single ASCII character and send that
|
|
character
|
|
.Pq Em some characters are not valid in expect .
|
|
.It \^^C
|
|
Substitute the sequence with the control character represented by C.
|
|
For example, the character DC1 (17) is shown as \^^Q
|
|
.Pq Em some characters are not valid in expect .
|
|
.El
|
|
.Sh TERMINATION CODES
|
|
The
|
|
.Nm
|
|
program will terminate with the following completion
|
|
codes.
|
|
.Bl -tag -width indent
|
|
.It 0
|
|
The normal termination of the program.
|
|
This indicates that the script
|
|
was executed without error to the normal conclusion.
|
|
.It 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.
|
|
.It 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
|
|
.Dv SIGINT .
|
|
.It 3
|
|
A timeout event occurred when there was an
|
|
.Em 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.
|
|
.It 4
|
|
The first string marked as an
|
|
.Dv ABORT
|
|
condition occurred.
|
|
.It 5
|
|
The second string marked as an
|
|
.Dv ABORT
|
|
condition occurred.
|
|
.It 6
|
|
The third string marked as an
|
|
.Dv ABORT
|
|
condition occurred.
|
|
.It 7
|
|
The fourth string marked as an
|
|
.Dv ABORT
|
|
condition occurred.
|
|
.It ...
|
|
The other termination codes are also strings marked as an
|
|
.Dv ABORT
|
|
condition.
|
|
.El
|
|
.Pp
|
|
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
|
|
.Nm
|
|
scripts may be found with UUCP
|
|
documentation.
|
|
The
|
|
.Nm
|
|
script was taken from the ideas proposed
|
|
by the scripts used by the uucico program.
|
|
.Pp
|
|
.Xr syslog 3 ,
|
|
.Xr syslogd 8
|
|
.Sh COPYRIGHT
|
|
The
|
|
.Nm
|
|
program is in public domain.
|
|
This is not the GNU public
|
|
license.
|
|
If it breaks then you get to keep both pieces.
|