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CKCKER.BWR "Beware File" for C-Kermit Version 5A -*- text -*- As of C-Kermit version: 5A(190) This file last updated: Wed Jun 7 10:00:03 1995 Authors: Frank da Cruz and Christine M. Gianone, Columbia University. Copyright (C) 1985, 1994, 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 Frank da Cruz: Columbia University Academic Information Systems 612 West 115th Street, New York, NY 10025 USA Email: fdc@columbia.edu C-Kermit 5A is documented in the book "Using C-Kermit" by Frank da Cruz and Christine M. Gianone, 1993, Digital Press / Butterworth-Heinemann, Woburn, MA, USA, ISBN 1-55558-108-0. Price: US $34.95. 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. NOTE: Some changes have been made to C-Kermit since the 5A(188) release. These are described in detail in the file CKCKER.UPD, which can be used as a supplement to "Using C-Kermit". 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. ckoker.bwr - IBM OS/2 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 This file contains the following sections: THE C-KERMIT COMMAND PARSER MULTIPLE SESSIONS NETWORK COMMUNICATION THE SERVICES DIRECTORY MODEMS AND DIALING DIALING HINTS AND TIPS TERMINAL EMULATION KEY MAPPING THE TRANSMIT COMMAND FILE TRANSFER SCRIPT PROGRAMMING 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. In this case, the -b option must be given after the -l option if it is to have any effect. If you specify an alternate initialization file on the command line (using the -y option) and the file doesn't exist or can't be opened, no error is reported. 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 of speed, 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\\*<ESC>", 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 20 characters. For array declarations and references, that includes the subscript. So, for example: \%a[\m(max_services)] is one character too long (this can be changed by redefining the symbol VNAML in ckuusr.h and recompiling C-Kermit). 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 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 \fliteral(\B)" (can be abbreviated, e.g. "out \flit(\B)") -- same for L or N. You can also use "output \\\\B" (yes, four backslashes); same for L or N. 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). NETWORK COMMUNICATION 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"). For details about TCP/IP, NETBIOS, and Named Pipes communication for OS/2 C-Kermit, see the CKOKER.BWR file. THE SERVICES DIRECTORY Until edit 190, the login macros (such as UNIXLOGIN, VMSLOGIN, etc), which are used in the services directory, had their respective system prompts hard-coded, so if the prompt on the system you were logging in to differed from the one in the macro, the macro would time out and report failure (even though it actually did log you in). These macros have been changed in edit 190 to allow you to override the default prompt. As explained on pp.297-301 of "Using C-Kermit", the format of a services directory entry is: entry-name login-macro-name user-id connection-macro-name + arguments For example: chemistry vmslogin ivan call hayes com1 2400 7654321 If you want to specify the system prompt to look for after logging in, you can do it by grouping it after the login macro name in braces, like this: chemistry {vmslogin CHEM:} ivan call hayes com1 2400 7654321 For reference, here are the standard login macros and the default prompts: UNIXLOGIN \13\10$\32 (i.e. CR, LF, dollar sign, space) VMSLOGIN \13\10$\32 (ditto) CISLOGIN CompuServe Information Service DOWLOGIN ENTER QUERY VMLINELOGIN (Not applicable) VMFULLOGIN (Not applicable) See the CKCKER.UPD file for a fuller explanation of the services directory. MODEMS AND DIALING The list of modem types supported by C-Kermit is obtained by typing: set modem ? at the C-Kermit> prompt. If you have a high-speed, error-correcting, data-compressing modem, you should generally use the following settings: set speed 57600 ; Or 38400, the highest supported by both Kermit & the modem set dial speed-matching off ; Use speed buffering. set flow rts/cts ; Use hardware flow control. set dial mnp on ; Enable error-correction and compression. DIAL MNP (which is actually a misnomer, because it applies to error correction and compression in general, including V.42 and V.42bis) is OFF by default because if you use an MNP modem to call a non-MNP modem, your MNP modem will send MNP protocol messages to the other modem, but the other modem will treat them as ordinary data and pass them through to the host. This usually results in your host session being locked up (e.g. autobaud to wrong speed, invalid login, etc). Also note that, at present, the SET DIAL MNP command is effective only for US Robotics and Telebit modem types. Always use hardware flow control if it is available (some operating systems do not support it). If it is not, use Xon/Xoff ("software") flow control between your computer and the modem, which means you must tell C-Kermit to "set flow xon/xoff" and you must configure your modem for this too. ADDING NEW MODEM TYPES TO C-KERMIT If you have a modem that is not directly supported by C-Kermit, you can define a new modem type for it. For example, suppose you have a Practical Peripherals PM14400FXMT V.32bis/V.42/V.42bis/MNP modem and you want to take full advantage of its features. You can dial with this modem, taking advantage of the support for Hayes-like modems that is already built into C-Kermit, but substituting an initialization string particular to the PP14400: set modem hayes ; Use Hayes-like dialog set line <whatever> ; Select the device your modem is on set speed 57600 ; Use high speed set dial speed-matching off ; Lock the speed set flow rts/cts ; Use hardware flow control set dial init ATQ0S2=43N1S37=11&K3&Q5S36=7S46=2S82=128\13 where: Q0 Result codes enabled S2=43 Escape character is "+" N1 Enable modulation negotiation S37=11 Enable V.32.bis &K3 Enable RTS/CTS (only if your C-Kermit version supports it) &Q5 Enable error correction S36=7 and compression with S46=2 automatic speed buffering S82=128 Pass BREAK signals through This can be turned into a dialing macro, PPDIAL, which you can use in place of the DIAL command: define PPDIAL - set modem hayes, - set line <whatever>, - ; Change this appropriately set speed 57600, - set dial speed-matching off, - set dial init ATQ0S2=43N1S37=11&K3&Q5S36=7S46=2S82=128\13, - dial \%1, - if success set flow rts/cts, - ; (If your C-Kermit version supports it) else end 1 If you put this definition into your CKERMOD.INI (or .mykermrc) file, then it will always be available for you to use, for example: C-Kermit> ppdial 7654321 And you can also use REDIAL in the normal way. See your modem manual for details about initialization strings. Most modern modems should be set up as in the example above but, naturally, the specific modem commands differ. Here are some sample modem initialization strings that should obtain settings equivalent to those made for the PP14400, for various other types of high-speed, error-correcting, data-compressing modems that are not specifically supported by Kermit's DIAL command. The maximum speed is shown after the modem name. These are offered in a form suitable for use in the SET DIAL INIT-STRING command (modem-command backslashes doubled, \13 at the end for carriage return), but with no guarantees -- see your modem manual for explanations of the commands and for further details. Each of these initialization strings attempts to: . Start modulation negotation at the highest available, e.g. V.34 (28800 bps) or V.32bis (14400bps), enabling fallback. . Fix the interface speed at C-Kermit's current speed, which should be 57600 or 38400 bps, whichever is the highest supported by both C-Kermit and the modem. Make sure you give the corresponding SET SPEED command first, and also tell C-Kermit to SET DIAL SPEED-MATCHING OFF. . Enable error correction and compression, enabling fallback. . Enable RTS/CTS hardware flow control. CAUTION: Not all C-Kermit implementations support RTS/CTS, in most cases because the underlying operating system does not support it. Type "check rts/cts" to see if your version of Kermit does support it. If it says "rts/cts available", you should be able to use the initialization string as is. If not, you might to remove or change the piece that is underlined like this. ^^^^^^^^^^^^^^^^^^^^ . Allow BREAK signals to be passed through transparently. AT&T DataPort 14400, 57600 bps: AT Q0 X6 &C1 &D2 &Q0 S84=0 \\Q3 %B14400 S41=1 S78=0 \\N7 %C1 \\K5\13 ^^^^ Boca 14.4 Faxmodem, 57600 bps: AT Q0W1&D2X4 S95=47 F10 S37=11 N1 &K3 S82=128 &Q5 S36=7 S46=138 \\N3 S48=7\13 ^^^ Hayes Ultra 144, 38400 bps: AT Q0W1X4 S87=28 &D2 S95=46 S37=11 N1 &K1 &K3 &Q5 S36=7 S38=1 S46=2 S48=7\13 ^^^^^^^ Multitech MT1432, 57600 bps: AT Q0 &Q1 X4 $SB57600 $MB14400 &E4 %E1 &E1 &E15 $BA0\13 ^^^ Practical Peripherals 14400FXMT, 57600 bps: AT Q0 W1 S95=47 &D2 X4 S2=43 N1 S37=11 &K3 &Q5 S36=7 S46=2 S82=128\13 ^^^ SupraFaxModem V.32bis and compatibles at 57600 bps: AT &F2 W1\13 ^^^ USR Sportster or Courier, 57600 bps: AT Q0 &S0 X4 &A3 &D2 &B1 &H1 &R2 &N0 &K1 &M4 &Y3\13 ^^^^^^^ Zoom Telephonics 14400, 57600 bps: AT Q0 W1 &D2 S95=47 X4 S37=11 &K3 S82=128 &Q5 S36=7 S46=138 S38=1\13 ^^^ CAUTION: Reportedly, these strings might be too long for some modems. If that is the case with yours, you can do one of the following: . Shorten the string by removing spaces and/or commands that are not necessary because they correspond to your modem's normal settings. . Change your dialing macro to simply OUTPUT these commands in small groups before issuing the DIAL command. Note the Supra example. It simply resets the appropriate factory profile for the modem, which automatically sets up the highest modulation, error correction, and compression, plus fallback and hardware flow control. This type of trick can probably also be used with most other modern Hayes-compatible (AT command set) V.32/V.32bis/V.34//V.42/V.42bis modems, provided your version of C-Kermit supports hardware flow control, and the modem is not buggy (some modems go nuts when given an ATZ or AT&Fx command). DIALING HINTS AND TIPS Remember: In many C-Kermit implementations (depending on the underlying operating system -- mostly OS/2 and System-V-based UNIX versions), 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 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 in "Using C-Kermit". Similarly, if your dialed connection drops when CARRIER 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 OFF. Automatic redialing: Here is a simple macro that dials and keeps redialing every thirty seconds until it gets an answer. Obviously, it can be elaborated with messages, counters, etc: define keep_on_dialing dial \%1, while failure { sleep 30, redial } 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. When dialing, it is better to give the SET FLOW RTS/CTS command after the DIAL command than before it. Here are a few points to clarify the purpose of SET DIAL SPEED-MATCHING: 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 DIAL SPEED-MATCHING OFF. 2. When DIAL 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 DIAL 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 DIAL SPEED-MATCHING OFF. If you have a high-speed, error-correcting, data-compressing, speed-buffering modem, you should always SET DIAL 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 ?" 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 pages 65-66 of "Using C-Kermit" 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. How to DIAL from a TCP/IP reverse terminal server (modem server): 1. (only if neccessary) SET TELNET ECHO REMOTE 2. SET HOST <terminal-server-ip-name-or-address> [ <port> ] 3. SET MODEM <modem-type> 4. (only if necessary) SET DIAL HANGUP OFF 5. DIAL <phone-number> The order is important. Although various modem-dialing strings are configurable, the DIAL MODEM-HANGUP string is not. For Hayes and Hayes-like modems it is ATQ0H0; the Q0 is to ensure that a result code is produced. In case the Q0 interferes with your normal setup (for example, if you keep your modems set to Q2), and dropping the connection does not restore the normal connection, you can define Kermit's ON_EXIT macro to send the appropriate modem configuration commands when Kermit exits, for example: define on_exit if > \v(local) 0 output ATQ2\13 The SET DIAL 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 current Telebit modems with spoofing enabled so if they are desired spoofing must be turned off. 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 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. Or you can use (or write) another program to accomplish the dialing, and then run C-Kermit "underneath" your dialing program by giving it the open file descriptor: kermit -l <n> -m unknown where <n> is the numeric file desciptor. (This feature is available in the UNIX and OS/2 versions of C-Kermit.) Or you can modify the ckudia.c module. NOTE: When you give a SET DIAL DIRECTORY command, C-Kermit keeps your dial directory file open until you give another SET DIAL DIRECTORY command, or until you EXIT. So, for example, you can't edit the dialing directory while you have it open. If you want to edit the dialing directory from within Kermit, you can close it by giving a SET DIAL DIRECTORY command with no file name. Then you can open it again with SET DIAL DIRECTORY <filename>. HAYES AND COMPATIBLE MODEMS C-Kermit should work correctly with Hayes and other modems that use the AT command set. These include Hayes 1200, Hayes 2400, and Hayes 9600 bps modems, compatibles, as well as Telebit and HST modems. See the next section for Telebit information. C-Kermit sends AT commands to the modem and then reads the modem's response. The software is designed to work whether the modem is configured to echo its commands (E1) or not (E0), and whether it replies with numeric (V0) or word (V1) result codes. C-Kermit does not change the echoing state or result code mode of the modem. However, C-Kermit issues the Q0 command to the modem to ensure that it *does* produce result codes. C-Kermit assumes the modem's Command Line Terminator (S3) is 13 (carriage return). If it isn't, C-Kermit's dialog with the modem probably won't work correctly. TELEBIT MODEM DIALING SUPPORT There are numerous Telebit modem models, with differing capabilities and features. C-Kermit tries to support them all in a model-independent way. To use a Telebit modem, any model, SET MODEM as follows: TELEBIT Dial and attempt to connect using the highest protocol appropriate to the interface speed between the computer and the modem, and fall back automatically to the highest protocol and speed supported by the answering modem. For example, if your interface speed is 19200 bps and you have a PEP-capable Telebit, it will start in PEP mode, fall back to one of the 2400-bps standards, then one of the 1200 bps standards, etc, depending on its configuration (see your Telebit manual). PEP-TELEBIT Dial in PEP mode, and connect only if the remote modem answers in PEP mode. Does not work with Telebit models that do not support PEP. See Table III. V32-TELEBIT Dial in V.32 mode (9600 bps), fall back from there. Works only with Telebit models that support V.32; see Table III. NOTE: V.32 calls are supposed to work no matter what your interface speed is, but it has been observed that when calling certain non-Telebit V.32 modems, the connection is not made successfully unless C-Kermit's interface speed to the Telebit is 9600. V42-TELEBIT Enable V.42 error correction, allowing fallback to MNP, and from there to direct (no error correction). NOTE: Fallback to MNP from V.42 is allowed even if DIAL MNP-ENABLE is OFF. Works only with Telebit models supporting V.42 error control. See Table III. SLOW-TELEBIT Dial at 2400 bps (V.22bis), fall back from there. Before attempting to use Telebits at high speeds, there is one problem you should be aware of: Most Telebit models do not "autobaud" at speeds higher than 19200 or 38400. If you want to make a high-speed call on such a modem, you must access it first at a lower speed, then give it a command to change to a higher speed, and then change Kermit's speed to match. For example, on the Telebit T3000: C-Kermit> set speed 19200 C-Kermit> connect AT (make sure it can read you) OK (it can) ATS51=7 (change it to 57600 bps) OK (it says OK, then changes its speed) ^\c (escape back to Kermit) C-Kermit> set speed 57600 (set Kermit to agree) Of course, you can automate this process using a script program. Or if you always want to dial out at 57600, you can save this setting in the modem, and then it will always use this speed (and won't autobaud any more). Telebit modems come in many models that differ not only as to features but also which commands control which features. The features, commands, and acceptable S-register values (and their meanings) can vary not only among models, but even among different ROM versions on the same model. Rather than have dozens of separate SET MODEM TELEBIT-xxx commands, C-Kermit queries the modem for its model number with an ATI command, and then adjusts its modem commands accordingly. Responses to the ATI command are shown in Table I. --------------------------------------------------------------------------- Table I: Telebit Modem ATI Command Responses --------------------------------------------------------------------------- ATI Model Numbers Examples --- ------------- -------- 123 Telebit in "total Hayes-1200" emulation mode 960 Telebit in Conventional Command (Hayes) mode 961 RA12C IBM PC internal original Trailblazer 962 RA12E External original Trailblazer, DCA Fastlink, or Racal-Milgo RM1822 963 RM12C Rackmount original Trailblazer 964 T18PC IBM PC internal Trailblazer-Plus (TB+) 965 T18SA, T2SAA, T2SAS External TB+, T1600, T2000, T3000, WB, and later or Ven-Tel Pathfinder EC18K (see below) 966 T18RMM Rackmount TB+ 967 T2MC IBM PS/2 internal TB+ 968 T1000 External T1000 969 ? QBlazer 971 T25SA External T2500 or T1500 (see below) 972 T25RM Rackmount T2500 --------------------------------------------------------------------------- Certain incompatible models show the same response to ATI. The ATI3 command is used to differentiate among them, as shown in Table II. --------------------------------------------------------------------------- Table II: Telebit Modem ATI3 Command Responses --------------------------------------------------------------------------- ATI If ATI3 Response Response Contains Telebit Model Is -------- ----------------- ---------------- 965 "T1600" T1600 965 "T3000" T3000 965 "World" WorldBlazer 965 "Version B" TrailBlazer-Plus or T2000 external version 1 965 "TBSA" TrailBlazer-Plus or T2000 external version 2 965 "TBRM" TrailBlazer-Plus or T2000 rackmount version 2 965 "DC" Ven-Tel Pathfinder EC18K (= TB+ version 1) 971 "T1500" T1500 971 (anything else) T2500 ---------------------------------------------------------------------------- The features of the various models and the commands used by Kermit to control them are shown in Table III. The commands in the PEP column are used to force PEP and allow compression (SET MODEM PEP-TELEBIT). The commands in the V.32 column are used with SET MODEM V32-TELEBIT. The commands in the V.42 column are used with SET MODEM V42-TELEBIT. The commands in the MNP column are used if SET DIAL MNP-ENABLE is ON and the modem type is TELEBIT, PEP-TELEBIT, or V32-TELEBIT, SLOW-TELEBIT, but not V42-TELEBIT; if SET MNP-ENABLE is OFF, the S-registers in the MNP column are set to 0. The Pass BREAK column shows the commands used to ensure that the modem passes the BREAK signal through (rather than treating it as an "escape-to-command-mode" signal). ------------------------------------------------------------------------------- Table III. Telebit Modem Features and Commands ------+---------------------+-------+--------+--------+-------------+---------- | | | | | | Kermit Model | PEP | V.32 | V.42 | MNP | Pass BREAK | Spoof ------+---------------------+-------+--------+--------+-------------+---------- TB | S50=255 S110=1 | No | No | S95=2 | S54=3 | PEP only TB+ | S50=255 S110=1 | No | ** | S95=2 | S54=3 | PEP only T2000 | S50=255 S110=1 | No | ** | S95=2 | S54=3 | PEP only T1000 | S50=255 S110=1 | No | No | S95=2 | S54=3 | PEP only T2500 | S50=255 S110=1 | S50=6 | No | S95=2 | S54=3 | PEP only T1500 | No | S50=6 | ** | S95=2 | S54=3 | PEP,V.32 ------+---------------------+-------+--------+--------+-------------+---------- T1600 | No | S50=6 | S180=2 | S180=3 | S61=0 S63=0 | PEP,V.32 T3000 | No | S50=6 | S180=2 | S180=3 | S61=0 S63=0 | PEP,V.32 QB | No | S50=6 | S180=2 | S180=3 | S61=0 S63=0 | No WB | S50=255S190=1S191=7 | S50=6 | S180=2 | S180=3 | S61=0 S63=0 | PEP,V.32 ------+---------------------+-------+--------+--------+-------------+---------- ** For V.42 error control: "S50=0 S95=2 S97=1 S98=3 S106=1". All models but the QBlazer support Kermit spoof (but see below). Group I (old command set): TB = Original TrailBlazer (PEP, MNP, V.22bis, V.22, Bell 212A & 103) TB+ = TrailBlazer-Plus = TrailBlazer + V.42 (but only in new ROMs) T1000 = TrailBlazer-Plus, speed <= 9600, no PEP compression T2000 = TrailBlazer-Plus + SDLC (not used by Kermit, so same as TB+) T2500 = TrailBlazer-Plus + V.32 (9600 bps) T1500 = T2500 minus PEP Group II (new command set): T1600 = V.32, MNP, V.22bis, V.22, V.23, Bell 212A & 103 QB = QBlazer = T1600 without Kermit spoof and minus some other options T3000 = T1600 + V.32bis (14400 bps) WorldBlazer = T3000 + PEP + LZ and V.42bis compression + 76800 & 115200 bps. C-Kermit does not attempt to control whether the modem changes its interface speed to match the connection speed -- that is up to you; you can configure the modem any way you prefer (using S51 or, to some extent on new-style modems S180 and S181), but make sure that the modem's configuration agrees with C-Kermit's DIAL SPEED-MATCHING setting. When DIAL SPEED-MATCHING is ON (the default), C-Kermit changes its interface speed automatically according to the speed reported in the modem's CONNECT message; when it is OFF, C-Kermit does not change speed. Most Telebit modems do not autobaud at speeds above 9600 or 19200 bps unless specially configured to do so, and even then most (maybe all) models will not autobaud at all at 57600 bps. Thus, to make a high-speed modem call with a Telebit, follow these steps: set modem telebit set line <whatever> set speed 19200 connect Now type AT and carriage return to make sure you get an OK result. Then type: ats51=7 and then carriage return. This changes the Telebit's interface speed to 57600 (use ats51=6 if your modem's or computer's top speed is 38400). Now escape back to Kermit and give these commands: set speed 57600 ; or 38400 set dial speed-matching off set dial mnp on and now you can place a high-speed, error-correcting, data-compressing call. The DIAL KERMIT-SPOOF command is only effective for the Telebit models that supply a Kermit spoof, that is, all but the QBlazer. If the Telebit model is TrailBlazer, TrailBlazer-Plus, T1000, T2000, or T2500, PEP mode is forced even if your SET MODEM command specified a Telebit modem type other than PEP-TELEBIT, because the Kermit spoof only works in PEP mode on those models. On the other models supporting the Kermit spoof, it works on both PEP connections and V.32 MNP (but not V.42) connections. Thus, you might also have to SET MODEM MNP-ENABLE ON in order to get the Kermit Spoof to work on these newer models when making a V.32 connection. SHOW DIAL does not show the complete initialization string for Telebit modems. Telebit modems are initialized in several steps, and the initialization command depends upon your current communication parameters, which model of Telebit modem you have (which C-Kermit learns during the modem initialization process), and other factors. If you use the SET DIAL INIT-STRING command to change the initialization string, this disables the multistep process and uses only the string that you have specified. If you want to use the built-in multi-step process, but you also want to override one or more of the settings that are done in this process, or add additional settings, you can use SET DIAL DIAL-COMMAND to add commands to the dial string (which is normally ATD%s\13), for example "SET DIAL DIAL-COMMAND AT&C1&D2S181=1DT%s\13". DIALING AND FLOW CONTROL If you have SET FLOW to any of the hardware options supported by your version of C-Kermit, such as RTS/CTS, and if C-Kermit knows how to set the flow control on your modem, it will do this as part of the DIAL command. Caution: . If C-Kermit's FLOW-CONTROL setting is Xon/Xoff or other type of software flow control, C-Kermit will not attempt to change your modem's flow control setting, since software flow control is most commonly used end-to-end. One way to engage Xon/Xoff flow control directly between C-Kermit and the local modem is to change your modem's DIAL INIT-STRING to do it. . If your version of C-Kermit does not support SET FLOW RTS/CTS (or other hardware options), then C-Kermit will not attempt to change your modem's flow control setting. Change your modem's DIAL INIT-STRING to do it. Hardware flow control options are presently handled only for Telebit modems. On other modem types, you can set the flow control outside of Kermit, or change Kermit's DIAL INIT-STRING. 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; if not, you can put the appropriate command in the DIAL INIT-STRING or DIAL-COMMAND. 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" (<pause>+++<pause>ATH0<CR>) will not work, so you should also be sure to SET DIAL MODEM-HANGUP OFF. TERMINAL EMULATION Except for the 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. KEY MAPPING Except in the OS/2 and Macintosh 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 300 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. THE TRANSMIT COMMAND Session logging is inactive during the TRANSMIT command, even if you have given a LOG SESSION command. FILE TRANSFER The recovery feature (RESEND command) that was added in edit 190, as noted in the CKCKER.UPD file, 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. When referring to MS-DOS, Atari ST, OS/2, or other file specifications that contain backslash characters in a C-Kermit command, you must 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 NOTE: But read about the new command, SET COMMAND QUOTING OFF, in CKCKER.UPD for a way around this. ANOTHER NOTE: In OS/2 C-Kermit 5A(190), this restriction is lifted as far as referring to files on the local OS/2 machine. You can now refer to these files using natural OS/2 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 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. Occasionally, when receiving files in remote mode using a large window size, attempts to cancel a file (X) can take a long time. 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. 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. 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. TELNET option negotiations are not handled during file transfer. So far, no ill effects have been noted. Why is Kermit file transfer over a TCP/IP connection slower than FTP? Because the Kermit program on the remote end of the connection is not running directly on a TCP socket, but rather running underneath a TELNET server, usually on a pseudoterminal and under a login shell, with the vast amounts of per-character overhead all of that implies. Future Kermit releases will be able to act directly as TCP servers, eliminating all this overhead. 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. SCRIPT PROGRAMMING The CKERMIT.INI file that was originally distributed with C-Kermit 5A(188) and (189) contained a nonfunctional CISLOGIN (CompuServe Login) macro. Fixed in CKERMIT.INI dated September 2, 1993, or later. 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 "#" 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) 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. 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. \v(incount) and \v(inchar) are NOT affected by the CLEAR command. GOTO can be used sort of like switch/case. For example, if you know that the value of \%a is 1, 2, or 3, you can "goto \%a" provided you have labels :1, :2, and :3. What it missing, however, is an automatic way to trap failing GOTOs, similar to the "default:" clause of a C switch() statement. The following script program: set count \ffiles(oofa.*) :loop send \fnextfile() if count goto loop does not work as expected. 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 line. To accomplish this type of operation: (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] - } 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. (End of CKCKER.BWR)