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C-Kermit 8.0 General Hints and Tips
Frank da Cruz
[1]The Kermit Project, [2]Columbia University
As of: C-Kermit 8.0.211, 17 March 2003
This page last updated: Sat Apr 10 16:37:37 2004 (New York USA Time)
IF YOU ARE READING A PLAIN-TEXT version of this document, it is a
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This document contains platform-independent C-Kermit hints and tips.
Also see the platform-specific C-Kermit hints and tips document for
your platform, for example:
for Unix. This document also applies to [5]Kermit 95 for Windows,
which is based on C-Kermit.
[ [6]C-Kermit ] [ [7]TUTORIAL ]
[ [20]Top ] [ [21]Contents ] [ [22]Next ]
Source-level patches for C-Kermit 8.0.211:
[ [23]Top ] [ [24]Contents ] [ [25]Next ]
These are not necessarily exhaustive lists.
1.1. C-Kermit 6.0
C-Kermit 6.0 was released 6 September 1996 and is completely
documented in [26]Using C-Kermit, 2nd Edition. The following
incompatible changes were made in C-Kermit 6.0:
* Unless you tell C-Kermit otherwise, if a serial or network
connection seems to be open, and you attempt to EXIT or to open a
new connection, C-Kermit warns you that an active connection
appears to be open and asks you if you really want to close it. If
you do not want these warnings, add SET EXIT WARNING OFF to your
customization file or script, or give this command at the prompt.
* The default for SET { SEND, RECEIVE } PATHNAMES was changed from
ON to OFF, to prevent unexpected creation of directories and
depositing of incoming files in places you might not know to look.
* The default for SET FILE INCOMPLETE was changed from DISCARD to
KEEP to allow for file transfer recovery.
* The default file-transfer block-check is now 3, rather than 1. If
the other Kermit does not support this, the two will drop back to
type 1 automatically unless the other Kermit fails to follow the
protocol specification.
* The default flow-control is now "auto" ("do the right thing for
each type of connection"), not Xon/Xoff.
* Backslash (\) is no longer a command continuation character. Only
- (hyphen, dash) may be used for this in C-Kermit 6.0 and later.
* Negative INPUT timeout now results in infinite wait, rather than 1
1.2. C-Kermit 7.0
C-Kermit 7.0 was released 1 January 2000. Its new features are
documented in the C-Kermit 7.0 Supplement,
[27] The following
incompatible changes were made in C-Kermit 7.0:
* The "multiline GET" command is gone. Now use either of the
following forms instead:
get remote-name local-name
get /as-name:local-name remote-name
If either name contains spaces, enclose it in braces (or, in
C-Kermit 8.0, doublequotes).
* To include multiple file specifications in a GET command, you must
now use MGET rather than GET:
mget file1 file2 file3 ...
* C-Kermit 7.0 and later use FAST Kermit protocol settings by
default. This includes "unprefixing" of certain control
characters. Because of this, file transfers that worked with
previous releases might not work in the new release especially
against a non-Kermit-Project Kermit protocol implementation (but
it is more likely that they will work, and much faster). If a
transfer fails, you'll get a context-sensitive hint suggesting
possible causes and cures. Usually SET PREFIXING ALL does the
* By default C-Kermit 7.0 and later send files in text or binary
mode by looking at each file to see which is the appropriate mode.
To restore the previous behavior, put SET TRANSFER MODE MANUAL and
the desired SET FILE TYPE (TEXT or BINARY) in your C-Kermit
initialization file.
* The RESEND and REGET commands automatically switch to binary mode;
previously if RESEND or REGET were attempted when FILE TYPE was
TEXT, these commands would fail immediately, with a message
telling you they work only when the FILE TYPE is BINARY. Now they
simply do this for you.
* SET PREFIXING CAUTIOUS and MINIMAL now both prefix linefeed (10
and 138) in case rlogin, ssh, or cu are "in the middle", since
otherwise <LF>~ might appear in Kermit packets, and this would
cause rlogin, ssh, or cu to disconnect, suspend,escape back, or
otherwise wreck the file transfer. Xon and Xoff are now always
prefixed too, even when Xon/Xoff flow control is not in effect,
since unprefixing them has proven dangerous on TCP/IP connections.
* In UNIX, VMS, Windows, and OS/2, the DIRECTORY command is built
into C-Kermit itself rather than implemented by running an
external command or program. The built-in command might not behave
the way the platform-specific external one did, but many options
are available for customization. Of course the underlying
platform-specific command can still be accessed with "!", "@", or
"RUN" wherever the installation does not forbid. In UNIX, the "ls"
command can be accessed directly as "ls" in C-Kermit.
* SEND ? prints a list of switches rather than a list of filenames.
If you want to see a list of filenames, use a (system-dependent)
construction such as SEND ./? (for UNIX, Windows, or OS/2), SEND
[]? (VMS), etc.
* In UNIX, OS-9, and Kermit 95, the wildcard characters in previous
versions were * and ?. In C-Kermit 7.0 they are *, ?, [, ], {, and
}, with dash used inside []'s to denote ranges and comma used
inside {} to separate list elements. If you need to include any of
these characters literally in a filename, precede each one with
backslash (\).
* SET QUIET { ON, OFF } is now on the command stack, just like SET
INPUT CASE, SET COUNT, SET MACRO ERROR, etc, as described on p.458
of [28]Using C-Kermit, 2nd Edition. This allows any macro or
command file to SET QUIET ON or OFF without worrying about saving
and restoring the global QUIET value. For example, this lets you
write a script that tries SET LINE on lots of devices until it
finds one free without spewing out loads of error messages, and
also without disturbing the global QUIET setting, whatever it was.
* Because of the new "." operator (which introduces assignments),
macros whose names begin with "." can not be invoked "by name".
However, they still can be invoked with DO or \fexecute().
* The syntax of the EVALUATE command has changed. To restore the
previous syntax, use SET EVALUATE OLD.
* The \v(directory) variable now includes the trailing directory
separator; in previous releases it did not. This is to allow
constructions such as:
cd \v(dir)data.tmp
to work across platforms that might have different directory
notation, such as UNIX, Windows, and VMS.
* Prior to C-Kermit 7.0, the FLOW-CONTROL setting was global and
sticky. In C-Kermit 7.0, there is an array of default flow-control
values for each kind of connection, that are applied automatically
at SET LINE/PORT/HOST time. Thus a SET FLOW command given before
SET LINE/PORT/HOST is likely to be undone. Therefore SET FLOW can
be guaranteed to have the desired effect only if given after the
* Character-set translation works differently in the TRANSMIT
command when (a) the file character-set is not the same as the
local end of the terminal character-set, or (b) when the terminal
character-set is TRANSPARENT.
1.3. C-Kermit 8.0
The following incompatible changes were made in C-Kermit 8.0:
* C-Kermit now accepts doublequotes in most contexts where you
previously had to use braces to group multiple words into a single
field, or to force inclusion of leading or trailing blanks. This
might cause problems in contexts where you wanted the doublequote
characters to be taken literally. Consult [29]Section 5 of the
[30]C-Kermit 8.0 Update Notes for further information.
* Using the SET HOST command to make HTTP connections is no longer
supported. Instead, use the new [31]HTTP OPEN command.
[ [32]Top ] [ [33]Contents ] [ [34]Next ] [ [35]Previous ]
Various command-related limits are shown in the following table, in
which the sample values are for a "large memory model" build of
C-Kermit, typical for modern platforms (Linux, Solaris, AIX, VMS,
etc). You can see the values for your version of Kermit by giving the
SHOW FEATURES command. The maximum length for a Kermit command (CMDBL)
also determines the maximum length for a macro definition, since
DEFINE is itself a command. The maximum length for a variable name is
between 256 and 4096 characters, depending on the platform; for array
declarations and references, that includes the subscript.
Item Symbol Sample
Value Definition
Number of characters in a command CMDBL 32763 ckucmd.h
Number of chars in a field of a command ATMBL 10238 ckucmd.h
Nesting level for command files MAXTAKE 54 ckuusr.h
Nesting level for macros MACLEVEL 128 ckuusr.h
Nesting level for FOR / WHILE loops FORDEPTH 32 ckuusr.h
Number of macros MAC_MAX 16384 ckuusr.h
Size of INPUT buffer INPBUFSIZ 4096 ckuusr.h
Maximum files to match a wildcard MAXWLD 102400 ckcdeb.h
Filespecs in MSEND command MSENDMAX 1024 ckuusr.h
Length for GOTO target label LBLSIZ 50 ckuusr.h
\fexecute() recursion depth limit CMDDEP 64 ckucmd.h
If you need to define a macro that is longer than CMDBL, you can break
the macro up into sub-macros or rewrite the macro as a command file.
In a pinch you can also redefine CMDBL and recompile C-Kermit. All of
these numbers represent tradeoffs: the bigger the number, the more
"powerful" Kermit in the corresponding area, but also the bigger the
program image and possibly disk footprint, and the longer it takes to
load and initialize.
In the interactive command parser:
* EMACS- or VI-style command line editing is not supported.
* Editing keys are hardwired (Ctrl-U, Ctrl-W, etc).
If you interrupt C-Kermit before it has issued its first prompt, it
will exit. This means that you cannot interrupt execution of the
initialization file, or of an "application file" (file whose name is
given as the first command-line argument), or of an alternative
initialization file ("-y filename"), and get to the prompt. There is,
however, one exception to this rule: you *can* interrupt commands --
including TAKE commands -- given in the '-C "command list"'
command-line argument and -- if there were no action commands among
the command-line arguments -- you will be returned to the C-Kermit
prompt. So, for example, if you want to start C-Kermit in such a way
that it executes a command file before issuing its first prompt, and
you also want to be able to interrupt the command file and get to the
prompt, include a TAKE command for the desired command in the -C
argument, for example:
kermit -C "take dial.scr"
At the command prompt, if you use the backslash (\) prefix to enter a
control character, space, or question mark into a command literally,
the backslash disappears and is replaced by the quoted character. If
it was a control character, it is shown as a circumflex (^). This
allows editing (backspace, delete, Ctrl-W) to work correctly even for
control characters.
Priot to C-Kermit 8.0, the only way to include a comma literally in a
macro definition -- as opposed to having it separate commands within
the definition -- is to enter its ASCII value (44) in backslash
notation, e.g.:
In C-Kermit 8.0 you can use constructions like this:
If you quote special characters in a filename (e.g. in the SEND
command), filename completion may seem to work incorrectly. For
example, if you have a file whose name is a*b (the name really
contains an asterisk), and you type "send a\\*<ESC>", the "b" does not
appear, nor will Ctrl-R redisplay the completed name correctly. But
internally the file name is recognized anyway.
Question-mark help does not work during execution of an ASKQ command.
The question marks are simply accepted as text.
In OUTPUT commands only, \B sends a BREAK signal, \L sends a Long
BREAK signal, and \N sends a NUL (ASCII 0). BREAK and Long BREAK are
special signals, not characters, and NUL is a character that normally
cannot be included in a C string, since it is the C string terminator.
If you really want to output a backslash followed by a B, an L, or an
N (as is needed to configure certain modems, etc), double the
backslash, e.g. "output \\B". In C-Kermit 7.0 or later, you can disarm
and re-arm the special OUTPUT-command escapes (\B, \L, and \N) with
When using the command-line processor ("kermit -l /dev/tty00 -b
19200", etc), note that in some cases the order of the command-line
options makes a difference, contrary to the expectation that order of
command-line options should not matter. For example, the -b option
must be given after the -l option if it is to affect the device
specified in the -l option.
[ [36]Top ] [ [37]Contents ] [ [38]Next ] [ [39]Previous ]
C-Kermit 7.0 and earlier do not support multiple sessions. When you
SET LINE (or SET PORT, same thing) to a new device, or SET HOST to a
new host, the previous SET LINE device or network host connection is
closed, resulting in hangup of the modem or termination of the network
connection. In windowing environments like HP-VUE, NeXTSTEP, Windows,
OS/2, etc, you can run separate copies of Kermit in different windows
to achieve multiple sessions.
To achieve multiple sessions through a single serial port (e.g. when
dialing up), you can install SLIP or PPP on your computer and then use
C-Kermit's TCP/IP support over the SLIP or PPP connection, assuming
you also have TCP/IP networking installed on your computer.
C-Kermit 8.0 has the same restriction on SET LINE and SET HOST
sessions: only one regular session (dialout, Telnet, etc) can be open
at a time. However, version 8.0 adds two new kinds of sessions: FTP
and HTTP; one or both of these can be open at the same as a regular
[ [40]Top ] [ [41]Contents ] [ [42]Next ] [ [43]Previous ]
FTP Client Bugs
The Unix C-Kermit 8.0.206 FTP client had the following bugs at the
time most of the 8.0.206 binaries were built for the C-Kermit 8.0
1. FTP MGET fails when directory segments contain wildcards, as in
"ftp mget */data/*.dat". Work around by doing a separate MGET for
each source directory.
2. FTP MGET can fail or produce random side effects if you have a
TMPDIR or CK_TMP environment variable definition in effect, or a
SET TEMP-DIRECTORY value, longer than 7 characters. Work around by
giving a SET TEMP-DIRECTORY command with a short value, such as
These two bugs are fixed in the source code that is included on the
CDROM, and also in Kermit 95 2.1.1. You can tell if a C-Kermit 8.0.206
binary has these fixes by typing SHOW VERSION; if it says "FTP Client,
8.0.200, 24 Oct 2002" it has the fixes; if the edit number is less
that 200, it doesn't, in which case can build a new binary from the
source code (or contact us and we'll try to get get one for you).
Making TCP/IP Connections Can Take a Long Time
The most frequently asked question in many newsgroups is "Why does it
take such a long time to make a Telnet connection to (or from) my
(e.g.) Linux PC?" (this applies to Kermit as well as to regular Telnet
1. Most Telnet servers perform reverse DNS lookups on the client for
security and/or logging reasons. If the Telnet client's host
cannot be found by the server's local DNS server, the DNS request
goes out to the Internet at large, and this can take quite some
time. The solution to this problem is to make sure that both
client and host are registered in DNS.
2. C-Kermit itself performs reverse DNS lookups unless you tell it
not to. This is to allow C-Kermit to let you know which host it is
actually connected to in case you have made a connection to a
"host pool" (multihomed host). You can disable C-Kermit's reverse
3. C-Kermit 7.0 and later strictly enforce Telnet protocol rules. One
such rule is that certain negotiations must be responded to. If
C-Kermit sends a such a negotiation and the host does not respond,
C-Kermit waits a long time for the reply (in case the network is
congested or the host is slow), but eventually will time out. To
eliminate the waits (and therefore risk possible protocol
mismatches -- or worse -- between Telnet client and server), tell
C-Kermit to SET TELNET WAIT OFF (or include the /NOWAIT switch
with the TELNET command).
The Rlogin Client
In multiuser operating systems such as UNIX and VMS, TCP/IP Rlogin
connections are available only to privileged users, since "login" is a
privileged socket. Assuming you are allowed to use it in the first
place, it is likely to behave differently depending on what type of
host you are rlogging in to, due to technical reasons having to do
with conflicting interpretations of RFC793 (Out-Of-Band Data) and
Rlogin (RFC1122)... "Specifically, the TCP urgent pointer in BSD
points to the byte after the urgent data byte, and an RFC-compliant
TCP urgent pointer points to the urgent data byte. As a result, if an
application sends urgent data from a BSD-compatible implementation to
an [44]RFC-1122 compatible implementation then the receiver will read
the wrong urgent data byte (it will read the byte located after the
correct byte in the data stream as the urgent data byte)." Rlogin
requires the use of OOB data while Telnet does not. Therefore, it is
possible for Telnet to work between all systems while BSD and System V
TCP/IP implementations are almost always a bad mix.
The Telnet Client
On a TCP/IP TELNET connection, you should normally have PARITY set to
NONE and (except in VMS C-Kermit) FLOW-CONTROL also set to NONE. If
file transfer does not work with these settings (for example, because
the remote TELNET server only gives a 7-bit data path), use SET PARITY
SPACE. Do not use SET PARITY MARK, EVEN, or ODD on a TELNET connection
-- it interferes with TELNET protocol.
If echoing does not work right after connecting to a network host or
after dialing through a TCP/IP modem server, it probably means that
the TELNET server on the far end of the connection is executing the
TELNET protocol incorrectly. After initially connecting and
discovering incorrect echoing (characters are echoed twice, or not at
all), escape back, give the appropriate SET DUPLEX command (FULL or
HALF), and then CONNECT again. For a consistently misbehaving
connection, you can automate this process in a macro or TAKE file.
TELNET sessions are treated just like serial communications sessions
as far as "terminal bytesize" and "command bytesize" are concerned. If
you need to view and/or enter 8-bit characters during a TELNET
session, you must tell C-Kermit to SET TERMINAL BYTESIZE 8, SET
If you SET TELNET DEBUG ON prior to making a connection, protocol
negotiations will be displayed on your screen. You can also capture
them in the debug log (along with everything else) and then extract
them easily, since all Telnet negotiations lines begin with
(uppercase) "TELNET".
[ [45]Top ] [ [46]Contents ] [ [47]Next ] [ [48]Previous ]
External modems are recommended because:
* They don't need any special drivers.
* They are less likely to interfere with normal operation of your
* You can use the lights and speaker to troubleshoot dialing.
* You can share them among all types of computers.
* You can easily turn them off and on when power-cycling seems
* They are more likely to have manuals.
Modems can be used by C-Kermit only when they are visible as or
through a regular serial port device. Certain modems can not be used
in this normal way on many kinds of computers: Winmodems, RPI modems,
Controllerless modems, the IBM Mwave, etc; all of these require
special drivers that perform some, most, or all of the modem's
functions in software. Such drivers are generally NOT available in
UNIX or other non-Windows (or non-OS/2, in the case of the Mwave)
In order to dial a modem, C-Kermit must know its repertoire of
commands and responses. Each modem make and model is likely to have a
different repertoire. Since Kermit has no way of knowhing which kind
of modem will be dialed, normally you have to tell it with a SET MODEM
TYPE command, e.g.:
set modem type usrobotics
set line /dev/cua0
set speed 57600
dial 7654321
In the early days, there was a wide variety of modems and command
languages. Nowadays, almost every modem uses the Hayes AT command set
(but with some differences in the details) and its startup
configuration includes error correction, data compression, and
hardware (RTS/CTS) flow control. As long as C-Kermit is capable of
hardware flow control (as it is on many, but not all, the platforms
where it runs, since some operating systems don't support it), the
modem can be dailed immediately, without lengthy configuration
dialogs, and in fact this is what SET MODEM TYPE GENERIC-HIGH-SPEED
does. In C-Kermit 8.0, GENERIC-HIGH-SPEED has become the default modem
type, so now it is usually possible to SET LINE, SET SPEED, and DIAL
without having to identify your modem. If this doesn't work, of
course, then you might have to fall back to the tradiational method:
Give a SET MODEM TYPE for a specific modem first, then SET LINE, SET
An important change in C-Kermit 6.0 is that when you give a SET MODEM
TYPE command to tell Kermit what kind of modem you have, Kermit also
sets a number of other modem-related parameters automatically from its
internal modem database. Thus, the order in which you give
modem-related commands is significant, whereas in prior releases they
could be given in any order.
In particular, MODEM SPEED-MATCHING is set according to whether the
modem is known to be capable of speed buffering. SET MODEM TYPE
HAYES-2400 automatically turns SPEED-MATCHING ON, because when the
Hayes 2400 reports a particular speed in its CONNECT message, that
means its interface speed has changed to that speed, and C-Kermit's
must change accordingly if it is to continue communicating. This might
cause some confusion if you use "set modem type hayes" for dialing a
more advanced type of modem.
The new default for flow control is "auto", meaning "do the right
thing for each type of connection". So (for example) if your version
of C-Kermit supports SET FLOW RTS/CTS and your modem also supports
RTS/CTS, then Kermit automatically sets its flow control to RTS/CTS
and set modem's flow control to RTS/CTS too before attempting to use
the modem.
For these reasons, don't assume that "set modem type hayes" should be
used for all modems that uses the Hayes AT command set. "set modem
type hayes" really does mean Hayes 1200 or 2400, which in turn means
no hardware flow control, and no speed buffering. This choice will
rarely work with a modern high-speed modem.
[ [49]Top ] [ [50]Contents ] [ [51]Next ] [ [52]Previous ]
If you have a high-speed, error-correcting, data-compressing,
speed-buffering modem, you should fix the modem's interface speed as
high as possible, preferably (at least) four times higher than its
maximum connection (modulation) speed to allow compression to work at
full advantage. In this type of setup, you must also have an effective
means of flow control enabled between C-Kermit and the modem,
preferably hardware (RTS/CTS) flow control. On platforms that do not
support hardware flow control, it is usually possible to select
software flow control (Xon/Xoff), and C-Kermit will do its best to set
the modem for local Xon/Xoff flow control too (but then, of course,
Ctrl-S and Ctrl-Q characters can not be transmitted on the
If you are having trouble dialing your modem, SET DIAL DISPLAY ON to
watch the dialing interactions between C-Kermit and your modem.
Consult Chapters 3-4 of [53]Using C-Kermit (2nd Ed) for modem-dialing
troubleshooting instructions. The following sections offer some
addtional hints and tips.
6.1. Syntax
If you want to dial a number that starts with #, you'll need to quote
the "#" character (as \# or \{35}), since it is also a comment
C-Kermit>dial #98765421-1-212-5551212 ; Looks like a comment
?You must specify a number to dial
C-Kermit>dial \#98765421-1-212-5551212 ; Works OK
C-Kermit>dial =#98765421-1-212-5551212 ; This works too
When using a dialing directory, remember what happens if a name is not
C-Kermit>dial xyzcorp
Lookup: "xyzcorp" - not found - dialing as given
This normally does no harm, but some modems might behave strangely
when given dial strings that contain certain letters. For example, a
certain German modem treats any dial string that contains the letter
"s" as a command to fetch a number from its internal list, and replies
OK to the ATD command, which is normally not a valid response except
for partial dialing. To avoid this situation, use:
lookup xyzcorp
if success dial
6.2. The Carrier Signal
Remember: In many C-Kermit implementations (depending on the
underlying operating system -- mostly Windows, OS/2, and
System-V-based UNIX versions, and in C-Kermit 7.0, also VMS), you
can't CONNECT to a modem and type the modem's dialing command (like
"ATDT7654321") manually, unless you first tell C-Kermit to:
This is because (in these implementations), the CONNECT command
requires the modem's Carrier Detect (CD) signal to be on, but the CD
signal doesn't come on until after dialing is complete. This
requirement is what allows C-Kermit to pop back to its prompt
automatically when the connection is hung up. See the description of
SET CARRIER-WATCH in "Using C-Kermit".
Similarly, if your dialed connection drops when CARRIER-WATCH is set
to AUTO or ON, you can't CONNECT back to the (now disconnected) screen
to see what might have happened unless you first SET CARRIER-WATCH
OFF. But sometimes not even SET CARRIER-WATCH OFF will help in this
situation: certain platforms (for example Unixware 2.1), once carrier
drops, won't let the application do i/o with the device any more. In
that case, if you want to use the device again, you have to CLOSE it
and OPEN it again. Or you can have Kermit do this for you
automatically by telling it to SET CLOSE-ON-DISCONNECT ON.
6.3. Dialing and Flow Control
Don't SET FLOW RTS/CTS if your modem is turned off, or if it is not
presenting the CTS signal. Otherwise, the serial device driver can get
stuck waiting for this signal to appear.
Most modern modems support RTS/CTS (if they support any hardware flow
control at all), but some computers use different RS-232 circuits for
the same purposes, e.g. DTR and CD, or DTR and CTS. In such cases, you
might be able to make your computer work with your modem by
appropriately cross-wiring the circuits in the cable connector, for
example the computer's DTR to the modem's RTS, and modem's CD to the
computer's CTS. HOWEVER, C-Kermit does not know you have done this. So
if you have (say) SET FLOW DTR/CD, C-Kermit will make no attempt to
tell the modem to use RTS/CTS. You probably did this yourself when you
configured the modem.
6.4. The Dial Timeout
If it takes your call longer to be completed than the timeout interval
that C-Kermit calculates, you can use the SET DIAL TIMEOUT command to
override C-Kermit's value. But beware: the modem has its own timeout
for completing the call. If it is a Hayes-like modem, C-Kermit adjusts
the modem's value too by setting register S7. But the maximum value
for S7 might be smaller than the time you need! In that case, C-Kermit
sets S7 to 0, 255, or other (modem-specific) value to signify "no
timeout". If Kermit attempts to set register S7 to a value higher than
your modem's maximum, the modem will say "ERROR" and you will get a
"Failure to initialize modem" error. In that case, use SET DIAL
TIMEOUT to override C-Kermit's calculation of the timeout value with
the highest value that is legal for your modem, e.g. 60.
6.5. Escape Sequence Guard Time
A "TIES" (Time-Independent Escape Sequence) modem does not require any
guard time around its escape sequence. The following text:
if sent through a TIES modem, for example because you were uploading
this file through it, could pop the modem back into command mode and
make it hang up the connection. Later versions of the Telebit T1600
and T3000 (version LA3.01E firmware and later), and all WorldBlazers,
use TIES.
Although the probability of "+++" appearing in a Kermit packet is
markedly lower than with most other protocols (see the [54]File
Transfer section below), it can still happen under certain
circumstances. It can also happen when using C-Kermit's TRANSMIT
command. If you are using a Telebit TIES modem, you can change the
modem's escape sequence to an otherwise little-used control character
such as Ctrl-_ (Control-Underscore):
AT S2=31
A sequence of three consecutive Ctrl-_ characters will not appear in a
Kermit packet unless you go to extraordinary lengths to defeat more
than a few of Kermit's built-in safety mechanisms. And if you do this,
then you should also turn off the modem's escape-sequence recognition
AT S48=0 S2=255
But when escape sequence recognition is turned off, "modem hangup"
(<pause>+++<pause>ATH0<CR>) will not work, so you should also SET
6.6. Adaptive Dialing
Some modems have a feature called adaptive dialing. When they are told
to dial a number using Tone dialing, they check to make sure that
dialtone has gone away after dialing the first digit. If it has not,
the modem assumes the phone line does not accept Tone dialing and so
switches to Pulse. When dialing out from a PBX, there is almost always
a secondary dialtone. Typically you take the phone off-hook, get the
PBX dialtone, dial "9" to get an outside line, and then get the phone
company's dialtone. In a situation like this, you need to tell the
modem to expect the secondary dialtone. On Hayes and compatible
modems, this is done by putting a "W" in the dial string at the
appropriate place. For example, to dial 9 for an outside line, and
then 7654321, use ATDT9W7654321:
(replace "9" with whatever your PBX's outside-line prefix is).
6.7. The Busy Signal
Some phone companies are eliminating the busy signal. Instead, they
issue a voice message such as "press 1 to automatically redial until
the number answers, or...". Obviously this is a disaster for modem
calls. If your service has this feature, there's nothing Kermit can do
about it. Your modem will respond with NO CARRIER (after a long time)
rather than BUSY (immediately), and Kermit will declare the call a
failure, rather than trying to redial the same number.
6.8. Hanging Up
There are two ways to hang up a modem: by turning off the serial
port's DTR signal (SET MODEM HANGUP-METHOD RS232-SIGNAL) or sending
the modem its escape sequence followed by its hangup command (SET
MODEM HANGUP-METHOD MODEM-COMMAND). If one doesn't work, try the
other. If the automatic hangup performed at the beginning of a DIAL
command causes trouble, then SET DIAL HANGUP OFF.
The HANGUP command has no effect when C-Kermit is in remote mode. This
is on purpose. If C-Kermit could hang up its own controlling terminal,
this would (a) most likely leave behind zombie processes, and (b) pose
a security risk.
If you DIAL a modem, disconnect, then SET HOST or TELNET, and then
HANGUP, Kermit sends the modem's hangup command, such as "+++ATHO".
There is no good way to avoid this, because this case can't reliably
be distinguished from the case in which the user does SET HOST
terminal-server, SET MODEM TYPE name, DIAL. In both cases we have a
valid modem type selected and we have a network connection. If you
want to DIAL and then later make a regular network connection, you
will have to SET MODEM TYPE NONE or SET DIAL HANGUP OFF to avoid this
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Watch out for terminal server's escape character -- usually a control
character such as Ctrl-Circumflex (Ctrl-^). Don't unprefix it in
Ciscos -- must often be told to "terminal download"... Cisco ASM
models don't have hardware flow control in both directions.
Many terminal servers only give you a 7-bit connection, so if you
can't make it 8-bit, tell Kermit to "set parity space".
The following story, regarding trouble transferring 8-bit files
through a reverse terminal server, was contributed by an Annex
terminal server user:
Using C-Kermit on an HP 9000 712/80 running the HP-UX 10.0
operating system. The HP was connected to a Xylogics Annex
MICRO-ELS-UX R7.1 8 port terminal server via ethernet. On the
second port of the terminal server is an AT&T Paradyne 3810 modem,
which is connected to a telephone line. There is a program which
runs on the HP to establish a Telnet connection between a serial
line on the Annex and a character special file on the HP (/dev
file). This is an Annex specific program called rtelnet (reverse
telnet) and is provided with the terminal server software. The
rtelnet utility runs on top of the pseudo-terminal facility
provided by UNIX. It creates host-originiated connections to
devices attached ot Annex serial ports. There are several command
line arguments to be specified with this program: the IP address of
the terminal server, the number of the port to attach to, and the
name of the pseudo-device to create. In addition to these there are
options to tell rtelnet how to operate on the connect: -b requests
negotiation for Telnet binary mode, -d turns on socket-leve
debugging, -f enables "connect on the fly" mode, -r removes the
device-name if it already exists, etc. The most important of these
to be specified when using 8 data bits and no parity, as we found
out, was the -t option. This creates a transparent TCP connection
to the terminal server. Again, what we assumed to be happening was
that the rtelnet program encountered a character sequence special
to itself and then "eating" those kermit packets. I think this is
all of the information I can give you on the configuration, short
of the values associated with the port on the terminal server.
How to DIAL from a TCP/IP reverse terminal server (modem server):
1. (only if necessary) SET TELNET ECHO REMOTE
2. SET HOST terminal-server-ip-name-or-address [ port ]
3. SET MODEM TYPE modem-type
4. (only if necessary) SET DIAL HANGUP OFF
5. (for troubleshooting) SET DIAL DISPLAY ON
6. DIAL phone-number
The order is important: SET HOST before SET MODEM TYPE. Since this is
a Telnet connection, serial-port related commands such as SET SPEED,
no effect. However, in C-Kermit 8.0, if the modem server supports
[59]RFC-2217 Telnet Com-Port Control protocol, these commands do
indeed take effect at the server's serial port.
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Except for the Windows, OS/2, and Macintosh versions, C-Kermit does
not emulate any kind of terminal. Rather, it acts as a
"semitransparent pipe", passing the characters you type during a
CONNECT session to the remote host, and sending the characters
received from the remote host to your screen. Whatever is controlling
your keyboard and screen provides the specific terminal emulation: a
real terminal, a PC running a terminal emulator, etc, or (in the case
of a self-contained workstation) your console driver, a terminal
window, xterm, etc.
Kermit is semitrantsparent rather than fully transparent in the
following ways:
* During a TELNET ("set host") session, C-Kermit itself executes the
TELNET protocol and performs TELNET negotiations. (But it does not
perform TN3270 protocol or any other type of 3270 terminal
* If you have changed your keyboard mapping using SET KEY, C-Kermit
replaces the characters you type with the characters or strings
they are mapped to.
* If you SET your TERMINAL CHARACTER-SET to anything but
TRANSPARENT, C-Kermit translates your keystrokes (after applying
any SET KEY definitions) before transmitting them, and translates
received characters before showing them on your screen.
* If your remote and/or local TERMINAL CHARACTER-SET is an ISO 646
7-bit national character set, such as German, French, Italian,
Swedish, etc, or Short KOI used for Cyrillic, C-Kermit's CONNECT
command automatically skips over ANSI escape sequences to avoid
translating their characters. Only ANSI/ISO standard
(VT100/200/300-like) 7-bit escape sequence formats are supported
for this purpose, no proprietary schemes like H-P, Televideo,
Tektronix, etc.
* If your version of C-Kermit includes SET TERMINAL APC command,
then C-Kermit's CONNECT command will handle APC escape sequences
if TERMINAL APC is not set to OFF (which is the default).
You can make C-Kermit fully transparent by starting it with the -0
(dash zero) command-line option.
If you are running C-Kermit under a console driver, or in a terminal
window, that emulates the VT100, and use C-Kermit to log in to a VMS
system, the console driver or terminal window (not Kermit) is supposed
to reply to the "what are you?" query (ESC Z) from the VAX. If it
doesn't, and you can't make it do so, then you can (a) live with the
"unknown terminal" problem; (b) tell VMS to SET TERMINAL/DEVICE=VT100;
(c) program a key using SET KEY to send the appropriate sequence and
then punch the key at the right time; or (d) use the VMSLOGIN macro
that is defined in CKERMIT.INI to do this for you automatically.
SET SESSION-LOG { TEXT, BINARY }, which is effective in UNIX and
AOS/VS but not other C-Kermit versions, removes CR, DEL, NUL, XON, and
XOFF characters (Using C-Kermit neglects to mention that XON and XOFF
are removed). The TEXT-mode setting is ineffective during SCRIPT
command execution, as well as on X.25 connections.
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Except in the terminal-emulating versions, C-Kermit's key mapping
facilities are limited to normal "ASCII" keys, and cannot be used with
function keys, arrow keys, arcane key combinations, etc. Since
C-Kermit runs on such a wide variety of hardware platforms (including,
for example, more than 360 different UNIX platforms), it is not
possible for C-Kermit to support every conceivable keyboard under
every release of every UNIX (or VMS, or ...) product on every
different kind of computer possibly under all manner of different
console drivers, even if it had the means to do so.
In technical terms, C-Kermit uses the read() function to read
keystrokes, and read() returns a single byte (value 0 through 255).
C-Kermit's SET KEY function applies to these single-byte codes.
"Extended function" keys, such as F-keys, arrow keys, etc, usually
return either a 2-byte "scan code" or else a character string (such as
an escape sequence like "<ESC> O p"). In both cases, C-Kermit has no
way to tell the difference between such multibyte key values, and the
corresponding series of single-byte key values. This could only be
done by accessing the keyboard at a much lower level in a highly
platform-dependent manner, probably requiring tens of thousands of
lines of code to support even a sampling of the most popular
workstation / OS combinations.
However, most workstation console drivers (terminal emulation windows,
etc) include their own key-mapping facility. For example in AIX, the
AIXterm program (in whose window you would run C-Kermit) allows
rebinding of the F1-F12 keys to arbitrary strings. The same is true of
Xterm and DECterm windows, etc. Consult the technical documentation
for your workstation or emulator. See sample Xterm (Xmodmap) mappings
in the [68]Unix C-Kermit Hints and Tips document.
The SET KEY command (except in Kermit 95) does not allow a key
definition to be (or contain) the NUL (\0) character.
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C-Kermit 7.0 is the first release of C-Kermit to use fast (rather than
robust and therefore slow) protocol defaults: long packets, sliding
windows, control-character unprefixing, and streaming where possible.
This makes most transfers (partner willing) dramatically faster "out
of the box" but might break some combinations that worked before. If
transfers with C-Kermit 7.0 or later fail where transfers worked with
earlier C-Kermit versions, try the following (one at a time, in this
1. SET PREFIXING ALL: Disables control-character unprefixing.
2. SET STREAMING OFF: Disables streaming.
3. CAUTIOUS: Selects medium but cautious protocol settings.
4. ROBUST: this command reverts to the most conservative protocol
Execution of multiple file transfers by C-Kermit from a command file
when in remote mode might exhibit long delays between each transfer.
To avoid this, just include the command "SET DELAY 0" in your command
file before any of the file-transfer commands.
File transfer failures can occur for all sorts of reasons, most of
them listed in Chapter 10 of [73]Using C-Kermit. The following
sections touch on some that aren't.
The [74]C-Kermit 7.0 Release Notes document SEND /COMMAND as taking an
argument, but it doesn't. Instead of SEND /COMMAND:{some command},
SEND /COMMAND [ other switches such as /AS-NAME: ] command [ arguments... ]
10.1. Laptops
Watch out for laptops and their assorted power-saver features; for
example, a built-in modem's "auto timeout delay" hanging up the
connection in the middle of a file transfer. Most modems, even if they
have this feature, do not have it enabled by default. But if you
experience otherwise inexplicable disconnections in the midst of your
Kermit sessions, check the modem manual for such things as "idle
timeout", "auto timeout", etc, and add the command to disable this
feature to Kermit's init string for this modem.
10.2. NFS
If uploading a large file to an NFS-mounted disk fails (or is
painfully slow), try uploading it to a local disk (e.g. /tmp on Unix)
and then copying to the NFS disk later.
10.3. Modems
If you are dialing out and find that downloads work but uploads don't,
try again with a lower serial-port speed. Case in point: dialing out
on a certain PC from Linux at 115200 bps using a USR Courier 56K
"V.Everything" external modem and RTS/CTS flow control. Downloads
worked flawlessly, uploads stopped dead after the first few packets
were sent. The modem lights showed constant retraining (ARQ light
blinks slowly), and the CTS light was off 95% of the time, allowing
nothing to get through. Reducing the serial port speed to 57600 bps
made the problems go away. Evidently the PC in question has a very
fast serial port, since dialing the same modem with a different PC at
115200 bps works without incident.
10.4. TCP/IP Connections
If you have trouble transferring files over a TCP/IP connection, tell
Kermit to SET PARITY SPACE and try again. If that doesn't work, also
try a shorter packet length or smaller window size (to compensate for
certain well-known broken Telnet servers), and/or SET RELIABLE OFF.
10.5. Multihop Connections
If you have a multihop connection, with the interior nodes in CONNECT
mode (Kermit, Telnet, Rlogin, or any other), you can expect (a) file
transfer to be slower, and (b) the connection to be less transparent
(to control characters, perhaps to the 8th bit) than a more direct
connection. C-Kermit 7.0 and later have a "-0" (dash-zero)
command-line option to make it 100% transparent in cases where it is
to be used in the middle.
10.6. Recovery
The recovery feature (RESEND command) that was added in version
5A(190) works only for binary-mode transfers. In order for this
feature to be useful at all, the default for SET FILE INCOMPLETE was
changed from DISCARD to KEEP. Otherwise an interrupted transfer would
leave no partial file behind unless you had remembered to change the
default. But now you have to pay closer attention to Kermit's messages
to know whether a transfer succeeded or failed -- previously, if it
failed, the file would not show up on the receiving end at all; in
5A(190) and later, you'll get a partial file which could easily be
mistaken for the complete file unless you change the default back to
DISCARD or read the screen messages, or keep a transaction log.
10.7. Filename Collisions
SET FILE COLLISION BACKUP is the default. This means:
* If you send the same file lots of times, there will be many backup
files. There is no automatic mechanism within Kermit to delete
them, no notion of a "version retention count", etc, but you can
use the PURGE command to clean them up.
* If a file arrives that has the same name as a directory, the file
transfer fails because Kermit will not rename a directory. Send
the file with another name, or use SET FILE COLLISION RENAME.
* If the directory lacks write permission, the file transfer fails
even if you have write access to the file that is being backed up;
in that case, switch to SET FILE COLLISION OVERWRITE or APPEND, or
send to a different directory.
SET FILE COLLISION UPDATE depends on the date/time stamp in the
attribute packet. However, this is recorded in local time, not
Universal Time (GMT), and there is no indication of time zone. The
time is expressed to the precision of 1 second, but some file systems
do not record with this precision -- for example, MS-DOS records the
file date/time only to the nearest 2 seconds. This might cause update
operations to send more files than necessary.
(This paragraph does NOT apply to UNIX, where, as of C-Kermit 7.0,
C-Kermit pipes incoming mail and print material directly the mail or
print program): When C-Kermit is receiving files from another Kermit
program that has been given the MAIL or REMOTE PRINT command, C-Kermit
follows the current filename collision action. This can be
disconcerting if the action was (for example) BACKUP, because the
existing file will be renamed, and the new file will be mailed (or
printed) and then deleted. Kermit cannot temporarily change to RENAME
because the file collision action occurs when the filename packet is
received, and the PRINT or MAIL disposition only comes later, in the
Attribute packet.
Watch out for SET FILE COLLISION RENAME, especially when used in
conjunction with recovery. Recall that this option (which is NOT the
default) renames the incoming file if a file already exists with the
same name (the default is to rename the previously existing file, and
store the incoming file with its own name). It is strongly recommended
that you do not use SET FILE COLLISION RENAME if you ever intend to
use the recovery feature:
* When the file is first received by C-Kermit, its name is changed
if another file already has the same name. When you RESEND the
same file after a failure, C-Kermit will probably try to append
the re-sent portion to the wrong file.
* Assuming that you get RESEND to work with FILE COLLISION RENAME,
C-Kermit, when receiving the remainder of the file during a RESEND
operation, will report back the wrong name. Nothing can be done
about this because the name is reported back before the receiving
Kermit program finds out that it is a recovery operation.
Also watch out for DISABLE DELETE, since this implicitly sets FILE
COLLISION to RENAME. And note tht DELETE is DISABLEd automatically any
time you Kermit is in local mode (i.e. it makes a connection). Also
note that for purposes of DISABLE and ENABLE, "set host *" connections
do not count as local mode even though, strictly speaking, they are.
10.8. DOS Pathnames
When referring to foreign MS-DOS, Windows, Atari ST, OS/2, or other
file specifications that contain backslash characters in a C-Kermit
command, you might have to double each backslash, for example:
C-Kermit>get c:\\directory\\foo.txt
This is because backslash is used in C-Kermit commands for introducing
special character codes, variables, functions, etc.
10.9. Cancellation
If attempting to cancel local-mode file reception at a very early
stage (i.e. before data packets are exchanged) with X or Z does not
work, use E or Ctrl-C instead, or wait until the first data packets
are sent.
If you cancel a transfer that is underway using X or Z, and a lot of
window slots are in use, it might take a while for the cancellation to
take effect, especially if you do this on the receiving end; that's
because a lot of packets might already be on their way to you. In that
case, just be patient and let Kermit "drain" them.
If C-Kermit is sending a file, remote-mode packet-mode breakout (three
consecutive Ctrl-C's by default) is not effective until after C-Kermit
sends its first packet. If C-Kermit is receiving a file or is in
server mode, it is effective right away. In the former case, the SET
DELAY value determines the earliest time at which you can break out of
packet mode.
10.10. Partner Peculiarities
When one or both partners is on an SCO operating system such as OSR5,
you might issue the command:
mapchan -n
to disable character-set conversion by the terminal driver. Similarly
for AIX:
setmaps -t NOMAP
When using C-Kermit to transfer files with the HP48SX calculator, you
must SET FLOW NONE. The HP48SX does not support flow control, and
evidently also becomes confused if you attempt to use it. You might
also need to use SET SEND PAUSE 100 (or other number). For greater
detail about transferring files the the HP-48, see:
Some communication programs have errors in their implementation of
Kermit attribute packets. If you get an error message from your
communication program like "Attribute error", tell C-Kermit to SET
ATTRIBUTES OFF. Better yet, switch to a real Kermit program.
Some communication software claims to implement Kermit sliding
windows, but does so incorrectly. If sliding window transfers fail,
set C-Kermit's window size to the smallest one that works, for
example, SET WINDOW 1.
For lots more detail about how to cope with defective Kermit partners,
* [76]Coping with Faulty Kermit Implementations (C-Kermit 7.0 and
* [77]Coping with Broken Kermit Partners (C-Kermit 8.0 and later).
The UNIX version of C-Kermit discards carriage returns when receiving
files in text mode. Thus, "bare" carriage returns (sometimes used to
achieve overstriking) are lost.
[ [78]Top ] [ [79]Contents ] [ [80]Previous ]
11.1. Comments Versus the SCRIPT Command
Remember that ";" and "#" introduce comments when (a) they are the
first character on the line, or (b) they are preceded by at least one
blank or tab within a line. Thus constructions like:
SCRIPT ~0 #--#--#
must be coded using backslash notation to keep the data from being
INPUT 5 \59 ; 59 is the decimal ASCII code for ";"
SCRIPT ~0 \35--#--# ; 43 is the decimal ASCII code for "#"
or, more simply:
INPUT 5 \; ; Just quote the semicolon
SCRIPT ~0 \#--#--# ; Just quote the "#"
11.2. Alphabetic Case and the INPUT Command
INPUT and MINPUT caseless string comparisons do not work for non-ASCII
(international) characters. Workaround: SET INPUT CASE OBSERVE. Even
then, the "lexically less than" and "lexically greater than"
operations (IF LLT, IF LGT) probably won't work as expected. The same
is true for the case-conversion functions \Flower() and \Fupper().
C-Kermit does not know the collating sequence for different character
sets and languages. (On the other hand, it might work depending on
such items as how Kermit was linked, whether your operating supports
"locales", etc)
11.3. NUL (0) Characters in C-Kermit Commands
You can't include a NUL character (\0) in C-Kermit command text
without terminating the character string in which it appears. For
echo In these brackets [\0] is a NUL
will echo "In these brackets [". This applies to ECHO, INPUT, OUTPUT,
and all other commands (but you can represent NUL by "\N" in an OUTPUT
string). This is because C-language strings are terminated internally
by the NUL character, and it allows all of C-Kermit's string
comparison and manipulation functions to work in the normal "C" way.
To illustrate:
INPUT 5 \0
is equivalent to:
is equivalent to:
INPUT operations discard and ignore NUL characters that arrive from
the communication device, meaning that they do not figure into
matching operations (e.g. A<NUL>B matches AB); they are not deposited
in the INPUT buffer (\v(input)); and they are not counted in
\v(incount), with two exceptions:
1. An arriving NUL character restarts the INPUT SILENCE timer.
2. An arriving NUL character terminates the INPUT command with the
SUCCESS condition if the INPUT command was given an empty search
string. In this case \v(incount) is set to 1.
Also, the \v(inchar) variable is null (completely empty) if the last
INPUT character was NUL. That is, there is no way to tell only by
looking at \v(inchar) the difference between a NUL that was INPUT and
no INPUT at all. If the INPUT command succeeded but \v(inchar) is
empty, then a NUL character was input. Also, \v(incount) will be set
to 1.
Here's a sample script fragment to read characters, possibly including
NUL, from the communication connection and write them to a file:
while true {
input 1 ; read one byte
if fail break ; timed out or connection closed
fwrite /char \%c \v(inchar) ; record the byte
This works because when \v(inchar) is NUL, that's equivalent to FWRITE
/CHAR having no text argument at all, in which case it writes a NUL
\v(incount) and \v(inchar) are NOT affected by the CLEAR command.
11.4. \ffiles() and \fnextfile() Peculiarities
The following script program:
for \%i 1 \ffiles(oofa.*) 1 {
send \fnextfile()
did not work as expected in C-Kermit 6.0 and earlier but does work in
C-Kermit 7.0 and later.
11.5. Commands That Have Only Local Effect
Certain settings are local to each command level, meaning that
subordinate command levels (macros or command files) can change them
without affecting their values at higher command levels. When a new
command level is invoked, the value is inherited from the previous
level. These settings are:
COUNT and \v(count)
This arrangement allows CASE, TIMEOUT, and ERROR settings, which are
used to control automatic exit from a command file or macro upon
error, to be automatically restored when the command file or macro
The COUNT variable follows this rule too, which permits nested SET
COUNT / IF COUNT loops, as in this example in which the inner loop
counts down from the current COUNT value of the outer loop (try it):
Keep in mind that an inferior command level cannot manipulate the
COUNT value held by a higher level. For example:
results in an infinite loop; the COUNT value remains at 5 because it
is never decremented at the same level at which it was set.
11.6. Literal Braces in Function Calls
Since braces are used in function calls to indicate grouping, there is
no way to pass literal braces to the function itself. Solution: Define
a variable containing the string that has braces. Example:
define \%a ab{cd
echo \fsubstring(\%a)
If the string is to start with a leading brace and end with a closing
brace, then double braces must appear around the string (which itself
is enclosed in braces):
define \%a {{{foo}}}
echo \fsubstring(\%a)
This also works for any other kind of string:
define \%a {{ab{cd}}
echo \fsubstring(\%a)
11.7. Defining Variables on the C-Kermit Command Line
To define variables on the C-Kermit command line, use the -C
command-line option with one or more DEFINE or ASSIGN commands. Note
that the C-Kermit command line must cope with the quoting rules of
your shell. Examples:
kermit -C "define \\%a foo, define phonenumber 7654321"
In this case we follow UNIX quoting rules by doubling the backslash.
Once C-Kermit starts, the \%a and \m(phonenumber) variables are
defined as indicated and can be used in the normal way.
In DOS or Windows or OS/2 the command would be:
kermit -C "define \%%a foo, define phonenumber 7654321"
Here we need to double the percent sign rather than the backslash
because of DOS shell quoting rules.
11.8. Per-Character Echo Check with the OUTPUT Command
Sometimes the OUTPUT command must be used to send commands or data to
a device in "echoplex" mode, meaning that characters must be sent one
at a time, and the next character can not be sent until the echo from
the previous one has been received. For example, a certain PBX might
have this characteristic. Let's say a Kermit script is used to program
the PBX. If characters are sent too fast, they can be lost. It would
seem that the command:
SET OUTPUT PACING milliseconds
could be used to take care of this, but the pacing interval is
constant and must be set large enough to allow even the slowest echo
to finish. If the script is large (an actual example is 14,000 lines
long), this can cause it to take hours longer than it needs to.
Here is a macro you can use to OUTPUT a string in an Echoplex
define XOUTPUT {
local \%c \%i
set output pacing 0
for \%i 1 \flen(\%*) 1 {
asg \%c \fsubstr(\%*,\%i,1)
output \%c
input 2 \%c
C-Kermit 7.0 or later is required.
It sends one character at a time and then waits up to 2 seconds for
the character to be echoed back, but continues to the next character
as soon as the echo appears, so no time is wasted. You can add an IF
FAIL clause after the INPUT in case you want to do something special
about failure to detect an echo within the timeout period. Obviously
you can also change the 2-second limit, and adjust the script in any
other desired way.
11.9. Scripted File Transfer
Sometimes a user complains that when she makes a connection by hand,
logs in, and transfers a file, there are no problems, but when she
scripts the the exact same sequence, the file transfer always fails
after a few packets. Here's a scenario where this can happen:
1. Upon logging in to the remote computer, it sends a "What Are You?"
escape sequence.
2. When you log in interactively, your terminal emulator sends the
response. This is invisible to you; you don't know it's happening.
3. When you script the login, and begin a file transfer immediately
upon logging in, the host still sends the "What Are You?"
sequence. Kermit's INPUT ECHO setting is ON by default, so the
escape sequence passes through to the terminal, and the terminal
sends its response. But by this time Kermit has already started
the file transfer.
4. By default, the local Kermit program examines the keyboard for
interruption characters between every packet. The "What Are You"
response is sitting in the keyboard buffer. Eventually Kermit will
read a character such as "c" that is a valid interruption
character, and the file transfer stops with "User cancelled".
The right way to handle this situation is to have your look for the
"What Are You?" sequence and send the response itself, as described in
Using C-Kermit, pp.429-431. Or you can work around it by telling the
local Kermit to "set input echo off" and/or "set transfer interruption
11.10. Other...
Escape sequences (or any strings that contain control characters)
can't be used as labels, GOTO targets, or SWITCH cases.
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C-Kermit 8.0 Unix Hints and Tips / [86]The Kermit Project /
[87]Columbia University / [88] / 10 April 2004