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NetBSD 6.1.5 - man page for chat (netbsd section 8)

CHAT(8) 										  CHAT(8)

NAME
       chat - Automated conversational script with a modem

SYNOPSIS
       chat [ options ] script

DESCRIPTION
       The  chat  program  defines  a conversational exchange between the computer and the modem.
       Its primary purpose is to establish the connection  between  the  Point-to-Point  Protocol
       Daemon (pppd) and the remote's pppd process.

OPTIONS
       -f chat file
	      Read the chat script from the chat file.	The use of this option is mutually exclu-
	      sive with the chat script parameters.  The user must have read access to the  file.
	      Multiple	lines  are  permitted  in  the	file.  Space or horizontal tab characters
	      should be used to separate the strings.

       -t timeout
	      Set the timeout for the expected string to be  received.	 If  the  string  is  not
	      received	within	the  time  limit then the reply string is not sent.  An alternate
	      reply may be sent or the script will fail if there is no alternate reply string.	A
	      failed script will cause the chat program to terminate with a non-zero error code.

       -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 spe-
	      cific 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  substitution within chat scripts using the standard
	      $xxx syntax.

       -v     Request that the chat script be executed in a verbose mode.  The chat program  will
	      then  log  the execution state of the chat script as well as all text received from
	      the modem and the output strings sent to the modem.  The default is to log  through
	      the  SYSLOG;  the  logging method may be altered with the -S and -s flags.  SYSLOGs
	      are logged to facility LOG_LOCAL2.

       -V     Request that the chat script be executed in a stderr verbose mode.  The  chat  pro-
	      gram  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 (to facility LOG_LOCAL2).

       -T phone number
	      Pass in an arbitrary 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 If  the  script  is  not	specified in a file with the -f option then the script is
	      included as parameters to the chat program.

CHAT SCRIPT
       The chat script defines the communications.

       A script consists of one or more "expect-send" pairs of strings, separated by spaces, with
       an optional "subexpect-subsend" string pair, separated by a dash as in the following exam-
       ple:

	      ogin:-BREAK-ogin: ppp ssword: hello2u2

       This line indicates that the chat program should expect the string "ogin:".  If	it  fails
       to  receive  a  login  prompt  within  the  time  interval allotted, it is to send a break
       sequence to the remote and then expect the  string  "ogin:".   If  the  first  "ogin:"  is
       received then the break sequence is not generated.

       Once  it  received  the	login  prompt  the chat program will send the string ppp and then
       expect the prompt "ssword:".  When it receives the prompt for the password, it  will  send
       the password hello2u2.

       A  carriage return is normally sent following the reply string.	It is not expected in the
       "expect" string unless it is specifically requested by using the \r character sequence.

       The expect sequence should contain only what is needed to identify the string.	Since  it
       is normally stored on a disk file, it should not contain variable information.  It is gen-
       erally not acceptable to look for time strings, network identification strings,	or  other
       variable pieces of data as an expect string.

       To  help  correct  for characters which may be corrupted during the initial sequence, look
       for the string "ogin:" rather than "login:".  It is possible that the leading "l"  charac-
       ter  may be received in error and you may never find the string even though it was sent by
       the system.  For this reason, scripts look for "ogin:" rather than "login:" and	"ssword:"
       rather than "password:".

       A very simple script might look like this:

	      ogin: ppp ssword: hello2u2

       In other words, expect ....ogin:, send ppp, expect ...ssword:, send hello2u2.

       In  actual  practice, simple scripts are rare.  At the vary least, you should include sub-
       expect sequences should the original string not be received.  For  example,  consider  the
       following script:

	      ogin:--ogin: ppp ssword: hello2u2

       This  would  be a better script than the simple one used earlier.  This would look for the
       same login: prompt, however, if one was not received, a single return sequence is sent and
       then it will look for login: again.  Should line noise obscure the first login prompt then
       sending the empty line will usually generate a login prompt again.

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 exam-
       ple, a program to prompt the user and receive a password typed in.

ABORT STRINGS
       Many modems will report the status of the call as a string.  These  strings  may  be  CON-
       NECTED  or  NO  CARRIER or BUSY.  It is often desirable to terminate the script should the
       modem fail to connect to the remote.  The difficulty is	that  a  script  would	not  know
       exactly	which modem string it may receive.  On one attempt, it may receive BUSY while the
       next time it may receive NO CARRIER.

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

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

       This sequence will expect nothing; and then send the string ATZ.  The expected response to
       this is the string OK.  When it receives OK, 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.  However, should the modem find a busy telephone,  it  will	send  the
       string  BUSY.   This  will  cause  the  string to match the abort character sequence.  The
       script will then fail because it found a match to the abort string.  If	it  received  the
       string  NO  CARRIER,  it  will  abort for the same reason.  Either string may be received.
       Either string will terminate the chat script.

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  stan-
       dard  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 explicitly 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 "Dialing your ISP...\n"
	      '' ATDT5551212
	      TIMEOUT 120
	      SAY "Waiting up to 2 minutes for connection ... "
	      CONNECT ''
	      SAY "Connected, now logging in ...\n"
	      ogin: account
	      ssword: pass
	      $ SAY "Logged in OK ...\n" 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:

	      Dialing 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 tele-
       phone.  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  key-
       word you can select which parts of the conversation should be visible.  For instance, with
       the following script:

	      ABORT   'BUSY'
	      ABORT   'NO CARRIER'
	      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 dialing systems which will hang up and call your sys-
       tem 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 incom-
       ing  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'
	      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 ...

TIMEOUT
       The initial timeout value is 45 seconds.  This may be changed using the -t parameter.

       To change the timeout value for the next expect string, the following example may be used:

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

       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.

       The timeout, once changed, remains in effect until it is changed again.

SENDING EOT
       The special reply string of EOT indicates that the chat program should send an EOT charac-
       ter to the remote.  This is normally the End-of-file character sequence.  A return charac-
       ter is not sent following the EOT.

       The EOT sequence may be embedded into the send string using the sequence ^D.

GENERATING BREAK
       The special reply string of BREAK 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.

       The break sequence may be embedded into the send string using the \K sequence.

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.

       ''     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.

       \b     represents a backspace character.

       \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.  (not valid in expect.)

       \d     Delay for one second.  The program uses sleep(1) which will delay to a  maximum  of
	      one second.  (not valid in expect.)

       \K     Insert a BREAK (not valid in expect.)

       \n     Send a newline or linefeed character.

       \N     Send  a null character.  The same sequence may be represented by \0.  (not valid in
	      expect.)

       \p     Pause for a fraction of a second.  The delay is 1/10th of a second.  (not valid  in
	      expect.)

       \q     Suppress writing the string to the SYSLOG.  The string ?????? is written to the log
	      in its place.  (not valid in expect.)

       \r     Send or expect a carriage return.

       \s     Represents a space character in the string.  This may be used when it is not desir-
	      able to quote the strings which contains spaces.	The sequence 'HI TIM' and HI\sTIM
	      are the same.

       \t     Send or expect a tab character.

       \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.)

       \\     Send or expect a backslash character.

       \ddd   Collapse the octal digits (ddd) into a single ASCII character and send that charac-
	      ter.  (some characters are not valid in expect.)

       ^C     Substitute the sequence with the control character represented by C.  For  example,
	      the character DC1 (17) is shown as ^Q.  (some characters are not valid in expect.)

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  substitution 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 SIG-
	      INT.

       3      A timeout event occurred when there was an expect string without	having	a  "-sub-
	      send"  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 lit-
       tle chance of succeeding during a retry.

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.

Chat Version 1.22			   22 May 1999					  CHAT(8)


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