ftp.barnyard.co.uk/2015.02.ftp.barnyard.co.uk.tar/ftp.barnyard.co.uk/robot-pd/23103.ZIP/23103A.DSK/qtchat.doc

Text File | 1997-12-18 | 22KB | 587 lines

QTERM chat scripts
==================

A chat script is a means for getting QTERM to automatically send and
receive text, this can be used to auto-dial, connect to remote systems,
log in to them, and do whatever else is wanted. In addition, chat scripts
have a number of commands available, to do such things as protocol sends
and receives, transfer of text files, and many other things.

There are two ways of invoking a chat script. Firstly when QTERM is
executed from CP/M, a chat script and parameters can be provided there:

    A>QTERM SCRIPT 1200

would be an example, alternatively the ^\ X command will prompt for a
filename, the response can be exactly the same:

    Filename: SCRIPT 1200

will have the same effect.

QTERM will look in several places to try to find the script. The first
thing it will do is to take the filename as given (subject to the
current default drive/user, which may have been changed by the !n or
^\ N commands). If this is not successful, QTERM then searches the
drive/user area that was active when it first started. It should be
noted that if the entry subroutine includes BDOS calls to change either
the drive or user, then the values rememberd by QTERM will be those on
exit from the entry subroutine. This provides a mechanism for setting
up a default script area, a place where QTERM will always try to find
scripts. In addition, if it can't find the script as a file in the
default script area, QTERM will look for a .LBR file /QTERM.LBR and
see if this library contains the script. The reason behind this is that
scripts tend be fairly small, and it is far more efficient to keep them
all together in one .LBR, since this saves disk space. It goes without
saying that QTERM cannot deal with squeezed or crunched scripts, they
must be saved in the .LBR as pure ASCII text files.

When a chat script is running it can be terminated prematurely by typing
^X on the keyboard: this will return to normal terminal mode.

There are two types of lines in a chat script: send/expect lines, and
command lines. Command lines are always started with a '!' character,
any other character starts a send/expect line.

Looking first at send/expect lines, they can contain up to six fields,
and the first two must be provided, even if they are empty. An example
of such a line is:

    -AT\r-OK\r\n-3-2-3-0-

In this example the '-' (first character) is the delimiter used to
separate fields. Any character can be used except for '!', but whatever
character is chosen cannot appear in the strings. Also note that
chosing a delimiter from the characters above 'z' in the ASCII character
set (i.e. '{', '|', '}', and '~') has a special effect, which is explained
below. Taking the fields in order they are SEND, EXPECT, TIME, TRIES,
SUCCESS, and FAIL. SEND is a string that is transmitted by QTERM, so in
the example above QTERM would transmit 'AT<carriage return>'. As was noted
above, delimiters above 'z' have a special effect: they cause the SEND
string to be written out slowly: there is a tenth of a second delay
after each character. EXPECT is a string that QTERM is looking for in
response to it's SEND string: so in the above example, QTERM would be
looking for the 'OK<carriage return><linefeed>' that a Hayes compatible
modem would respond with, when presented with 'AT<return>'.

The remining four fields are all decimal numbers, and can be omitted
as QTERM will provide default values. TIME is the number of seconds
to wait before assuming failure, if not given it defaults to 15. TRIES
is the number of times to retry on failure, so taking our first example,
TRIES is 2. If QTERM matched the EXPECT string on the first sending of
SEND, all is well, but on the first failure it would resend the SEND string
and look for the EXPECT string a second time. If it failed on this second
attempt, only then would it consider this line to have failed. SUCCESS
specifies the line number to transfer to in the chat script if it matched
the EXPECT string. The default for this is the line following the current
line. FAIL is the line to transfer to if the EXPECT string is not
matched. This can be a line in the chat script, or as shown above 0 is
allowed, which terminates the script immediately.

In the example above, the success and fail values are given as simple
line numbers, it is also possible to use labels in chat scripts, see !:
below for an explanation of how to define a label. If a label is being
used, the line might look like this:

    -ATDT5551234\r-CONNECT-30--`connect-`fail-

In this case, the `connect and `fail are label usages, and cause transfer
to wherever the corresponding label is. Label useage is introduced with the
backquote character `, which must be followed by the label itself, with no
intervening white space: -` connect- will not work. Using an undefined label
does not directly cause an error, but the substitution of the non-existant
label will usually create a line that cannot be parsed, thus flagging the
error.

In another example, if the first line were:

    -AT\r-OK\r\n--5-

since TIME is empty, it defaults to 15, but as TRIES is 5, this line
would try five times before giving up. Note also from this example
that there are two ways of causing QTERM to default a value: an empty
field (TIME) or end of the string (SUCCESS and FAIL). Note that the
closing '-' after the 5 for TRIES is necessary. On the basis of this,
the absulute minimum line is:

    -send-expect-

This uses all four defaults: 15 seconds timeout, 1 try, success goes to
the next line, failure terminates the script. The idea behind these
defaults is that a collection of simple send/expect lines like the above
allow a "conversation" to be held with the remote system.

It is possible that either of SEND or EXPECT can be empty: an empty SEND
causes nothing to be sent, but the EXPECT must be matched to continue;
an empty EXPECT automatically matches. Note that if both are empty then
the chat script will terminate when it reaches that line, so a line like:

    ---

will serve as a means to terminate a chat script, returning to terminal
mode.

Command lines in chat scripts start with '!', and following the '!' is
a command letter. If input is needed (e.g. for a '!b' or '!s' line)
it should be placed after the command letter:

    !b 1200 8n1 -5 30 500 +\x13\x11

As is shown in the above example, spaces are permitted after the command
letter, but not before.

Several of the ! commands correspond to ^\ commands available from terminal
mode: the !b above would set the baud rate etc., just like the corresponding
^\ B command would.

Commands available in this group are:

!,    hangup
!.    break
!B    set baud rate
!E    set local echo
!H    set half duplex
!J    toggle junking of control characters
!L    set linefeed send for 'P'
!M    set bit 7 mask
!N    select new drive/user
!V    toggle VT100 emulation
!W    toggle split window mode
!K    program function key
!P    print file to remote
!U    invoke user function
!R    protocol receive
!S    protocol send
!X    activate chat script
!Q    exit QTERM

Note also that the toggles ('!E', '!H', '!J', '!L', '!M', '!V' and '!W')
behave a little differently. Since the state of these toggles is not defined
when a chat script starts, with one exception (!W) there are three ways of
invoking these. Using '!H' as an example:

    !h

behaves as would an <escape> 'H' in normal operation, i.e. it toggles
the half duplex switch. However, if the following is given:

    !h 1

the trailing '1' forces half duplex to be enabled, irrespective of
it's original state, and:

    !h 0

guarantees to turn half duplex off. The other toggles work in the same
manner: a trailing '0' always disables, and a trailing '1' always
enables. !W is a little different, in that there are three possibilities:
window mode off, window mode on with big receive, and on with small. Also
allowing a pure toggle could have undefined results, since if window mode
were toggled on, there would be no indication what size was wanted. As
a result of this, there are three forms for the !W command in a script:

    !w 0

forces window mode off,

    !w b

forces it on with a big receive window, and:

    !w s

forces it on, but with a small window. With all these toggles (!h etc. and
!w) the options above are guaranteed, using any other option letters will
have undefined results.

The 'X' command to activate a chat script can be used to chain scripts
together: when an 'X' is encountered the specified chat script is
invoked, however the current script is lost: it is overwritten by the
new one.

There are other commands that are not normally available are as follows:


!a - This simply alerts it's passing by ringing the terminal bell, this
may be useful if a chat script is being used to repeatedly call a number
until a connection is made: by putting a !a into the script, the
system will beep when a connection is made.


!f - Capture an ASCII text file. Since 'C' catch files are disabled during
chat script operation, 'F' is provided as an alternative means for data
capture. A typical 'F' line would be:

    !f b:catch.txt 6 string

This would open B:CATCH.TXT for output, then send 'string' out, and
transfer all subsequent data to that file until a timeout of 6 seconds
occurred. As with files opened by ^\ C, the specified file will be opened
for append if it already exists, assuming it is writable. If it exists,
but is read only, then QTERM will not do the open. 'string' is a string
that can contain backslash escape sequences, just like a SEND string in
normal chat operation. Any timeout can be given, up to about 250 seconds.
Note that since this uses the same buffer as the <escape> C command, if
there is already a catch file open, it will be automatically closed prior
to execution of a '!f'.


!: - Define a label. Label usage was described above: the '`' character
introduces a label usage. NOTE that this is the BACKQUOTE character, not
the usual single quote character. To define a label, simply include a
line of the form:

!: connect

in the script. A few comments may make labels easier to use, firstly
they cannot be longer than seven characters, and where they are defined
there should be no trailing blanks. When a label is used, it is done by
means of a simple text substitution: after seeing a '`' character, QTERM
tries to match the following text with a label in the script, and it
stops at the first match. So if you have two labels one of which is a
prefix of the other, the results can be unpredictable. As a byproduct
of this, undefined labels do not generate an error (they just become
line zero), but the text substitution doesn't remove the label, so the
resulting line usually generates an error. In the event that a '`'
character is needed as part of a send or expect string, it can be
escaped by preceeding it with a $, so the line:

    .send.exp$`ect.

will look for exp`ect, whereas:

    .send.exp`ect.

will not work, it would try to look for and substitute the label 'ect'.


The commands !@ and !# can be used for variable manipulation. Their
main purpose is to prevent infinite loops in chat scripts. In the
following example:

    !: reset
    .AT\r.OK\r\n.5.5.
    .ATDT5551212\r.CONNECT.30..`connect.`reset.
    !: connect
    . ........

if the system being called is off line and not answering, QTERM will
loop here for ever. The !@ and !# provide the ability to keep count and
terminate the loop after some specified number of tries.

    !@ var term +/- term

is the form of an @ line. var is a single letter variable (there are 26
available: a through z), and term is either a number or a variable. This
is very simplistic, in that two terms must be present: to set a variable
simply say something like:

    !@ a 5 + 0

the operator can be either + or - and they act as you would expect. so:

    !@ a a - 1

will subtract 1 from a, or:

    !@ a a + b

will add b to a, etc. etc. Note that variables are recognised in either
upper or lower case:

    !@ A a + B

would have exactly the same effect as the line above. Note that these are
single bytes, so there is some risk of working with values above 255.

!# tests variables: the general syntax is:

    !# var operator term line

where var is a variable letter, term is a variable or a number, and the
operator can be '=' to test for equality, '#' to test for inequality, '<'
to check for less than and '>' to test for greater than. line is simply
the line number in the script to go to is the test succedes. Note that this
also provides a goto capability:

    !# a = a line

will always go to line, since a is always equal to itself. In this case,
line can be a label usage:

    !# a = a `doit

All variables are initialized to zero when the first script in a series is
invoked, but values are retained when a !x command chains from one script
to another.


Two commands have been added to manipulate the appearance of chat scripts:

    !> This is a line of text\r\n

!> simply prints the text, after processing '\' escapes. Note that
leading and trailing spaces are ignored, so the above case would start
with the 'T' of 'This'. In order to start or end with a with a space,
\x20 can be used.

    !%

This command is actually several different commands rolled into one:
!% o manipulates the echoing of characters received from the modem
while the script is running:

    !% o 1

forces modem echo on,

    !% o 0

forces it off, and:

    !% o

simply switches state. In the same manner, !% m controls printout of
the 'Match: OK' messages that are printed when QTERM matches the expect
string in a send/expect line.


As a complement to !>, teh !< command can be used to take keyboard input,
and make decisions based on what happens. This includes four subcommands
altogether:

    !< -

The '-' causes QTERM to prompt for a line of input using CP/M's BDOS
buffered command. The line is then saved, and can be tested with the !< =
command:

    !< = string line

If the input read in the !< - command is 'string' then transfer to line
(which can be a label). Note that string is NOT processed for escapes,
since the is intended only for printable ascii text comparisons.

This allows for such things as multiple choice:

    !> \r\nSelect system to call\r\n
    !> 1. System 1 ..... \r\n
    !> 2. System 2 ..... \r\n
    !> 3. System 3 ..... \r\n
    !: prompt
    !> Enter 1, 2 or 3:\x20
    !< -
    !< = 1 `sys1
    !< = 2 `sys2
    !< = 3 `sys3
    !> Error, invalid input\r\n
    !# a = a `prompt

Where the first 4 lines print a menu, the next line defines a label. Then
comes a prompt, followed by an input command. After this, the line is
checked against 1, 2 and 3, and a jump is made to the appropriate label.
If there is no match an error message is printed, and the !# a = a line
is used as a goto, since a is always equal to a.

In a similar manner, '!< .' and '!< ,' provide "hot key" comparisons, the
!< . command simply reads a single character from the keyboard, and !< ,
compares against a single character value just like !< = does:

    !< , \r `return

would be the test for a hot key input of a single carriage return. Note that
in this case, \ escapes are permitted.


The ![ command provides a similar function to the !< command, but it
works on text coming from the modem. There are three forms:

    ![ -

reads text from the modem. In this instance there are two ways that
reading can end:

    ![ - 15

would simply read text for 15 seconds. This numeric timeout must be
provided, but in addition up to four extra strings can be provided:

    ![ - 5 .string1.string2.string3.string4.

in which case input will terminate when 5 seconds have elapsed, or one
of the four strings is read. In this line, the '.' following the 5 is a
delimiter, this serves to separate the strings exactly like the delimiter
in a send / expect line. Not all four strings need to be there:

    ![ - 5 .OK.ERROR.

is acceptable, but the trailing delimiter must be there after the last
string. In addition to scanning for the four lines, QTERM keeps the last
sixty-four characters seen in a buffer, these can then be inspected with
![ = and ![ + lines. These do very similar functions, in that they both
look for a string in the last 64 characters seen.

    ![ = string line

searches the saved text for the string, which in this case can include
\ escapes. If string occured anwhere in the last 64 characters, control
goes to line. ![ + looks exactly the same, but the difference is whether
the test is done on seven or eight bit data: ![ = just compares the least
significant seven bits, ignoring the parity bit, whereas ![ + compares
all eight. Note also that the strings provided in the ![ - line are only
checked in seven bit mode.


The !~ command has been added for rudimentary file manipulation
during chat script operation. Three options exist:

    !~ - file

will erase a file. Note that QTERM will silently ignore this command
if the file doesn't exist, or if it is write protected. As with all
filenames, a drive/user can be given:

    !~ - d15:foo.bar

does like you'd expect.

    !~ = newname = oldname

renames a file: note that if a drive/user is given on oldname, it will
be ignored: newname completely defines where the action will happen.
This will fail silently if newname already exists, or if old name doesn't,
or if oldname does exist but is write protected.

    !~ + newname = oldname

copies a file. In this case a file can be copied to a different
drive / user, so if needed a drive / user spec should be attached to
oldname. This will fail silently if newname exists or if oldname doesn't.
These can be used to good effect when QTERM is sending text files as
messages to a BBS, after sending the file with a !P command, a !~ - will
erase it, or files can be erased after uploading, or a file might be
renamed after a batch download.


Parameters can be passed to chat scripts, in much the same way as to
SUBMIT operation: invoking a script:

    SENDFILE b3:*.asm

where there is a line in it:

    !s xky $1

causes the line to become:

    !s xky b3:*.asm

Warning: when a script is invoked directly from CP/M the parameters will all
be forced to upper case - this is a byproduct of the behaviour of the CCP.
It is for this reason that variables are recognised in both upper and lower
case: there are interesting things that can be done by mixing $n parameters
and variables: more in a minute.

In some cases it may be desirable to set a default value for a parameter,
a further line has been added to do this:

    !$n stuff

the '!' and '$' are just that, 'n' is the number of a parameter ('1'
through '9') and stuff will become the default value. In the following
case:

    !$3 default

if parameter 3 is not set (i.e. blank) it is expanded to default,
otherwise it is left alone. This might be useful when using one script
to call at one of several baud rates:

    CALLBBS 1200

could be done in conjunction with:

    !b $1 8n1 .....

inside CALLBBS. However if the script is invoked:

    CALLBBS

without a parameter, and the following line:

    !$1 2400

exists, then the baud rate in the !b command would default to 2400. In
order for these default set commands to work, they MUST be provided in
the correct sequence:

    !$2 something
    !$1 hello

will do very strange things. Also skipping values will do unexpected things,
as will putting spaces in the default string. A place where this can be used
to good effect is a script chain that calls several BBS's. By running a
variable from 0 to 25 to escape the infinte loop described above:

    !: reset
    !@ a a + 1
    !# a > 25 `exit
    .AT\r.OK\r\n.5.5.
    .ATDT5551212\r.CONNECT.30..`connect.`fail.
    !: fail
    .XXX\r.YYY.30.5.`reset.`reset.
    !: connect

when time runs out, this jumps to exit. Now, consider the following:

    !$1 y
    !@ n 26 + 0
    !@ a $1 + 0

Taking these lines in order: the first defaults parameter 1 to y
The second sets variable n to 26. The last sets a to the variable
named by parameter 1, so if the script is invoked:

    CALLBBS N

$1 will be N, and the last line will set a to 26 (n + 0). So when
control enters the loop above, a is already set to 26, and the script
immediately goes to `exit, thus bypassing the board. However, if it
is invoked as just:

    CALLBBS

$1 defaults to y, and line three sets a to 0, thus causing the BBS to
be tried. By repeating this for several boards:

    CALLBBS Y N Y Y N

will call the first, third and fourth, but bypass two and five. VERY
IMPORTANT NOTE: in a sequence of chat scripts, chained by the !x command
the parameters are lost after the !x command. However, by saying

    !x script param1 param2 param3

parameters can be passed from one script to another, and indeed other
parameters can be added, and some removed.

As is done with labels, $n parameters are handled by simple text
substitution, so a little care will make their use easier. As was
described above, '$' is used to escape '`' characters in strings, it is
also used to escape itself. i.e. to actually place a '$' character in a
string say '$$', so that:

    .send.exp$$ect.

would look for the string 'exp$ect'. There are only three things that
can follow a '$' sign: either '$' or '`' for escaping purposes,
and '1' through '9' for parameter substitution. Placing any other
character after a '$' will have an undefined result.


As a final note, any other command character is silently ignored,
this can be put to use to introduce comments. At this stage, !; is
not in use, and this is the official comment entry, it is guaranteed
that !; will never be used for a command line function in a QTERM
chat script.