CKCBWR.TXT "Beware File" for C-Kermit Version 6.0 -*- text -*- As of C-Kermit version: 6.1.194 This file last updated: Mon Jun 15 10:47:15 1998 Authors: Frank da Cruz and Christine M. Gianone, Columbia University. Copyright (C) 1985, 1998, Trustees of Columbia University in the City of New York. The C-Kermit software may not be, in whole or in part, licensed or sold for profit as a software product itself, nor may it be included in or distributed with commercial products or otherwise distributed by commercial concerns to their clients or customers without written permission of the Office of Kermit Development and Distribution, Columbia University. This copyright notice must not be removed, altered, or obscured. Report problems, suggestions, fixes, etc, to: The Kermit Project Columbia University 612 West 115th Street New York NY 10025-7799 USA Email: kermit-support@columbia.edu Web: http://www.columbia.edu/kermit/ News: comp.protocols.kermit.misc C-Kermit 6.0 is documented in the book "Using C-Kermit" by Frank da Cruz and Christine M. Gianone, Second Edition, 1997, Digital Press / Butterworth- Heinemann, Woburn, MA, USA, ISBN 1-55558-164-1. Price: US $41.95. Available in book and computer stores, or order by phone, call Columbia University at +1 212 854-3703, or Butterworth-Heinemann at +1 800 366-2665. A German edition is available from Verlag Heinz Heise in Hannover, Germany. WHAT IS IN THIS FILE This is the "beware file" for C-Kermit. It contains hints and tips, frequently asked questions (and answers), troubleshooting advice, limitations and restrictions, known bugs, etc, that apply to all C-Kermit variations. This file is supplemented by a system-specific "beware file" for each major system where C-Kermit runs: ckuker.bwr - All variations of UNIX: HP-UX, AIX, SCO, Solaris, etc. ckvker.bwr - Digital Equipment Corporation VMS and OpenVMS cklker.bwr - Stratus VOS ckdker.bwr - Data General AOS/VS ckmker.bwr - Apple Macintosh ckiker.bwr - Commodore Amiga cksker.bwr - Atari ST ck9ker.bwr - Microware OS-9 ckpker.bwr - Bell Labs Plan 9 This file contains the following sections: (1) INCOMPATIBLE CHANGES IN VERSION 6.0 (2) THE C-KERMIT COMMAND PARSER (3) MULTIPLE SESSIONS (4) NETWORK COMMUNICATION (5) THE SERVICES DIRECTORY (6) MODEMS AND DIALING (7) DIALING HINTS AND TIPS (8) TERMINAL SERVERS (9) TERMINAL EMULATION (10) KEY MAPPING (11) THE TRANSMIT COMMAND (12) FILE TRANSFER (13) SCRIPT PROGRAMMING (1) INCOMPATIBLE CHANGES These are not necessarily exhaustive lists. 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 SET LINE or SET HOST or TELNET, 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. . 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. . The default flow-control is now "auto" ("do the right thing"), 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 second. And in version 6.1: . The "multiline GET" command is gone. Now use: get or: get /as-name: If either name contains spaces, enclose it in braces. . To request list of files from the server, you must now use MGET rather than GET: mget file1 file2 file3 ... (2) THE C-KERMIT COMMAND PARSER 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 have any effect. In the interactive command parser: . VMS-style command editing (arrow keys, etc) is not supported. . 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" Reportedly, if you attempt to interrupt Kermit while it is executing its initialization file, and you do this rapidly enough, e.g. by sending a constant stream of Ctrl-C's at a very high rate, depending on the underlying operating system (reported only on a couple versions of UNIX), duplicate Kermit processes might be created -- cause unknown, cure unknown, workaround: don't do it. 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. 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.: DEFINE ROWS MODE CO80\{44}\%1 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\\*", the "b" will 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. The maximum length for a variable name is 64 characters. For array declarations and references, that includes the subscript. Sample Some other maximums to watch out for: Symbol Value Defined in Nesting level for command files: MAXTAKE 30 ckuusr.h Nesting level for macros: MACLEVEL 50 ckuusr.h Nesting level for FOR / WHILE loops: FORDEPTH 10 ckuusr.h Number of macros: MAC_MAX 256 ckuusr.h Size of INPUT buffer: INPBUFSIZ 256 ckuusr.h Maximum files to match a wildcard: MAXWLD varies ck?fio.c Filespecs in MSEND command: MSENDMAX 100 ckuusr.h Length of MSEND or GET string: FSPECL 300 ckuusr.h Length for GOTO target label: LBLSIZ 50 ckuusr.h Number of characters in a command: CMDBL 1024 ckucmd.h Number of chars in a field of a command: ATMBL 256 ckucmd.h \fexecute() recursion depth limit: CMDDEP 20 ckucmd.h The actual values of most of these items can vary with version and configuration, and are listed by SHOW FEATURES. ASK and ASKQ strip leading and trailing spaces from what the user types. This happens way down deep in the command parser -- it's nothing special about ASK and friends. The only way around this that works in both C-Kermit and MS-DOS Kermit is for the user (the one who is responding to the ASK prompt) to type (the first) leading space as "\32" and the (final) trailing space as "\32". In this example, the password begins with 2 leading blanks and ends with two trailing blanks, and "Passwd:" is the ASK prompt: Passwd:\32 secret \32 Of course, the user could also type *all* blanks as \32. In OUTPUT commands only, \B and \\B send a BREAK signal, and \L and \\L send a Long BREAK signal, and \N and \\N send 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), use "output \\B". In C-Kermit 6.1 or later, you can disarm and re-arm the special OUTPUT-command escapes (\B, \L, and \N) with SET OUTPUT SPECIAL-ESCAPES { OFF, ON }. (3) MULTIPLE SESSIONS C-Kermit does 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, 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. On UNIX systems that support the "term" program, you can establish a connection to another UNIX system with C-Kermit and then achieve multiple sessions using "term" client programs like trsh (see ckuker.bwr and the term documentation for details). (4) NETWORK COMMUNICATION 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. And 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 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 implementation are almost always a bad mix. 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 COMMAND BYTESIZE 8, and SET PARITY NONE. If you SET TERMINAL DEBUG ON or SET DEBUG SESSION (same thing), TELNET protocol negotiations will be displayed on your screen. But most of the interesting negotiations happen at the time the SET HOST or TELNET command is given, before CONNECT mode is entered, so you won't see them on your screen. However, you can still capture them in the debug log ("log debug"). C-Kermit version 6.0 has a new set of SET TCP commands, to control TCP-level parameters, such as "keepalive" protocol (that allows C-Kermit to detect more quickly and reliably when a connection is broken). Use SHOW NET to see their values and SET TCP to change them. (5) THE SERVICES DIRECTORY Is now explained fully in "Using C-Kermit", 2nd Edition, Chapter 7. (6) MODEMS AND DIALING The list of modem types supported by C-Kermit is obtained by typing: set modem type ? at the C-Kermit> prompt. Note that the ITU-T (V.25bis) modem type is only for asynchronous mode, not synchronous (HDLC) mode -- there is no support in C-Kermit for synchronous communication (except for SET NET X.25, which is only available on certain platforms). Modems can be used by C-Kermit only when they are visible as or through a regular serial port device. Note that 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) platforms. 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. The new default for flow control is "auto", meaning "do the right thing". So (for example) if your version of C-Kermit supports SET FLOW RTS/CTS and your modem also supports RTS/CTS, then Kermit will automatically set its flow control to RTS/CTS *and* set modem's flow control to RTS/CTS too before attempting to use the modem. (7) DIALING HINTS AND TIPS 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 6.1, 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: SET CARRIER-WATCH OFF 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. 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 might get stuck waiting for this signal to appear. 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. Here are a few points to clarify the purpose of SET MODEM SPEED-MATCHING: 0. The name was changed from SET DIAL SPEED-MATCHING to SET MODEM SPEED-MATCHING in edit 192, as part of the overhaul of the dialing features. 1. This command does not do anything at all to the modem. Rather, it is used to inform C-Kermit about the modem's configuration: whether the modem's interface speed is "fixed", or it changes its interface speed when a connection is made. In the latter case, C-Kermit changes its own speed in response to the speed given in the modem's CONNECT message. By default, SPEED-MATCHING is ON, so Kermit does indeed attempt to change its speed. If your modem is set to have a fixed interface speed, you must SET MODEM SPEED-MATCHING OFF. 2. When MODEM SPEED-MATCHING is ON: (a) Your modem must be configured to report its *interface* speed in the CONNECT message, rather than the connection (modulation) speed. (b) Your computer (and C-Kermit) must support all connection speeds that might be reported by your modem. SET SPEED ? will give you a list of the speeds that your version of C-Kermit knows about. 3. If conditions (a) and (b) cannot be satisfied, then you must: (a) Configure your modem to lock its interface speed (b) Tell C-Kermit to SET MODEM SPEED-MATCHING OFF To illustrate, suppose you have a V.32bis modem. When it connects to a remote V.32bis modem, it might issue a message like: CONNECT 14400 But 14400 bps is not a speed that is supported by certain operating systems and so C-Kermit might fail to adjust its speed according to this report. Therefore, you must lock the modem's interface speed at a higher speed (such as 19200, 38400, or 57600) that is supported by C-Kermit, set C-Kermit to the same speed, and tell C-Kermit to SET MODEM SPEED-MATCHING OFF. If you have a high-speed, error-correcting, data-compressing, speed-buffering modem, you should always SET MODEM SPEED-MATCHING OFF, and you should fix the modem's interface speed as high as possible, preferably 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. C-Kermit knows about a large number of modems, depending on how it was built (type "set modem type ?" and "show features" for further info). This knowledge is imbedded in the SET MODEM and DIAL commands. 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 "Using C-Kermit" (2nd Ed) for modem-dialing troubleshooting instructions. 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". WARNING: Certain modems might have a maximum dial timeout shorter than what Kermit expects it to be. 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. 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 , SET MODEM TYPE , 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 MODEM HANGUP RS232 to avoid this phenomenon. The SET MODEM KERMIT-SPOOF command works only for Telebit and US Robotics modem types; it is OFF by default. You may wish to experiment with large packets (1K or greater) and various window sizes with spoofing disabled in the modem. In most situations the transfer rates achieved by Kermit with sliding windows and long packets are better than with protocol spoofing turned on. Also, attribute (A) packets are not passed by Telebit modems with spoofing enabled so if they are desired spoofing must be turned off. 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. In Kermit 95, this is accomplished with: SET PBX-OUTSIDE-PREFIX 9W (replace "9" with whatever your PBX's outside-line prefix is). DEC modems... Reportedly, these don't work right when connected to a DEC terminal server -- result codes are never reported (on the other hand, this might be a modem configuration problem). Dialing "by hand", "blind" still works. Also, reportedly "For people who do have DEC modems directly connected to DEC computers the DF03, DF100-series, and DF200-series modem dialers should work. The only thing that is not straightforward is that the DF124-CA, DF124-CM modems must use the DF200-series since they speak Digital Modem Command Language (DMCL) and AT commands. The Digital Scholar Plus is a DF242 so it uses the DF200-series." If C-Kermit's dialing methods are insufficient for your purposes, you can write a C-Kermit script program to do the dialing. (7.1) DIALING AND FLOW CONTROL 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. (7.2) ESCAPE SEQUENCE GUARD TIME A "TIES" (Time-Independent Escape Sequence) modem does not require any guard time around its escape sequence. The following text: +++ATH0 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. Newer 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 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 altogether: AT S48=0 S2=255 But when escape sequence recognition is turned off, "modem hangup" (+++ATH0) will not work, so you should also be sure to SET DIAL MODEM-HANGUP OFF. (8) TERMINAL SERVERS How to DIAL from a TCP/IP reverse terminal server (modem server): 1. (only if necessary) SET TELNET ECHO REMOTE 2. SET HOST [ ] 3. SET MODEM 4. (only if necessary) SET DIAL HANGUP OFF 5. DIAL The order is important. Watch out for terminal server's escape character -- usually a control character such as Ctrl-Circumflex (Ctrl-^). Don't unprefix it in Kermit ! 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 (begin quote): 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. If I can provide any other details, just let me know. Thanks again for your help. (end quote) (9) TERMINAL EMULATION Except for the Windows, OS/2, and Macintosh versions, C-Kermit does not emulate any kind of terminal. Rather, it acts more or less as a "transparent 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. There are several exceptions to the "transparent pipe" rule: - 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 emulation.) - 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). 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. (10) KEY MAPPING 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. 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 system-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, on an IBM RS/6000, the AIXterm program (in whose window you would run C-Kermit) allows rebinding of the F1-F12 keys to arbitrary strings. The same might or might not be true of DECterm windows, Sun "vttool" or "crttool" windows, etc. Consult the technical documentation for your workstation or emulator. The SET KEY command (except in OS/2) does not allow a key definition to be (or contain) the NUL (\0) character. (11) THE TRANSMIT COMMAND Session logging is inactive during the TRANSMIT command, even if you have given a LOG SESSION command. (12) FILE TRANSFER 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. The recovery feature (RESEND command) that was added in edit 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 edit 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. 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 will be 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. Automatic directory creation for received files does not work for pathnames given in the "-a" command-line argument. There are no command-line arguments for "set file names { literal, converted }" or "set { send, receive } pathnames { on, off }", but you can include these (or any other) commands on the command line in the -C option string. When referring to 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. If you are sending this GET command to another copy of C-Kermit running as a server, for example on OS/2 or the Atari ST, it too treats backslashes as prefix characters, so you will need 4 (yes, 4) copies of each backslash: C-Kermit>get c:\\\\directory\\\\foo.txt But read about the new command, SET COMMAND QUOTING OFF, in the manual. ANOTHER NOTE: In Kermit 95, this restriction is lifted as far as referring to files on the local PC. You can now refer to these files using natural PC notation, e.g. C-Kermit>send c:\letters\oofa.txt 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. Workarounds: 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 long time 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 (Ctrl-C Ctrl-C 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 will be effective right away. In the former case, the SET DELAY value determines the earliest time at which you can break out of packet mode. 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, such as MS-DOS Kermit. 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). The fullscreen file transfer display will not work right if your terminal type is set incorrectly, or is not known to the host operating system. Even when it does work, it might slow down your file transfers a bit, especially on high-speed network connections. On certain small computers, it has been reported to cause increased disk activity due to swapping or paging. The fullscreen display is not particularly useful with speaking or Braille devices. In these cases, use SET FILE DISPLAY CRT or SET FILE DISPLAY SERIAL. If you have trouble transferring files over a TCP/IP connection, give the command: SET PARITY SPACE and try again. If that doesn't work, also try a shorter packet length. On the other hand, if file transfers through a TCP/IP connection work, but are very slow, use a longer packet length, 2000 or more, and also try increasing the window size. Also, make sure FLOW is NONE since TCP/IP handles flow control itself, and XON/XOFF processing only slows things down. Some communication software claims to implement 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 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. 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. - If a file arrives that has the same name as a directory, the file transfer fails. 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 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. SET FILE COLLISION OVERWRITE is risky, use it with caution. Under certain conditions, the existing file can be deleted even if the incoming file is refused. This paragraph does NOT apply to UNIX, where, as of C-Kermit 6.1, 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. The STATISTICS command will produce an incorrect efficiency report if (a) it does not know the true communication speed (e.g. on a network connection), or (b) it knows the true serial interface speed to a modem, but the modem is using a different communication speed with the other modem. Similarly, in these circumstances, C-Kermit's automatic calculation of the packet timeout interval might also be incorrect, which can cause file transfers to fail. One solution to the latter problem is to SET SEND and RECEIVE TIMEOUT to appropriate values for your true communication speed and packet length. 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. (13) SCRIPT PROGRAMMING 13.1. 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. Thus constructions like: INPUT 5 ; SCRIPT ~0 #--#--# must be coded using backslash notation to keep the data from being ignored: INPUT 5 \59 ; 59 is the decimal ASCII code for ";" SCRIPT ~0 \43--#--# ; 43 is the decimal ASCII code for "#" or, more simply: INPUT 5 \; ; Just quote the semicolon SCRIPT ~0 \#--#--# ; Just quote the "#" 13.2. Alphabetic Case and the INPUT Command INPUT and REINPUT 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) 13.3. 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 example: 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: INPUT 5 and: INPUT 5 ABC\0DEF is equivalent to: INPUT 5 ABC INPUT operations discard and ignore NUL characters that arrive from the communication device, meaning that they do not figure into matching operations (e.g. AB 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. \v(incount) and \v(inchar) are NOT affected by the CLEAR command. 13.4. \ffiles() and \fnextfile() Peculiarities The following script program: for \%i 1 \ffiles(oofa.*) 1 { send \fnextfile() } does not work as expected in C-Kermit 6.0 and earlier. The SEND command (and any other command that parses a filename, including TAKE) implicitly calls the same internal function that \ffiles() calls, and thus destroys the file list set up in the first call to \ffiles(). In 6.1 and later, a separate list is kept, so the following technique is not needed in the newer versions. To work around the problem in C-Kermit 6.0 and earlier: (1) give the wild filespec to \ffiles(); (2) loop through the file list and assign each filename to an array element; (3) use the array of filenames in subsequent file-related commands. Example: asg \%n \ffiles(\%1) declare \&f[\%n] for \%i 1 \%n 1 { asg \&f[\%i] \fnextfile() } for \%i 1 \%n 1 { send \&f[\%i] } 13.5. 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: CASE COUNT and \v(count) INPUT CASE INPUT TIMEOUT MACRO ERROR TAKE ERROR 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 exits. 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): DEFINE INNER WHILE COUNT { WRITE SCREEN { Inner:}, SHOW COUNT } SET COUNT 5 WHILE COUNT { WRITE SCREEN Outer:, SHOW COUNT, DO INNER } Keep in mind that an inferior command level cannot manipulate the COUNT value held by a higher level. For example: DEFINE OOFA SHOW COUNT, IF COUNT GOTO LOOP SET COUNT 5 :LOOP OOFA ECHO Done 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. NOTE: "WHILE COUNT" did not work prior to edit 095 of ckuusr.c, 19 Jan 93. 13.6. 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) ab{cd 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) {foo} This also works for any other kind of string: define \%a {{ab{cd}} echo \fsubstring(\%a) ab{cd 13.7. 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. Note that you can not set values for \%1..\%9 this way. The -C command-line option defines a macro called CL_COMMANDS whose definition is the material between the quotes, and then executes it. But \%1..\%9 are local to the macro they are passed to or defined in, and cease to exist when the macro exits. 13.8. 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 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 environment: define XOUTPUT { local \%c set output pacing 0 while defined \%1 { asg \%c \fsubstr(\%1,1,1) asg \%1 \fsubstr(\%1,2) output \%c input 2 \%c } } Usage: xoutput string-with-no-spaces or: xoutput { string that contains spaces } C-Kermit 6.0 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. (End of CKCBWR.TXT)