ckcbwr.txt

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   XOFF characters (Using C-Kermit neglects to mention that XON and XOFF
   are removed). The TEXT-mode setting is ineffective during SCRIPT
   command execution, as well as on X.25 connections.
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  9. KEY MAPPING

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   Except in the terminal-emulating versions, C-Kermit's key mapping
   facilities are limited to normal "ASCII" keys, and cannot be used with
   function keys, arrow keys, arcane key combinations, etc. Since
   C-Kermit runs on such a wide variety of hardware platforms (including,
   for example, more than 360 different UNIX platforms), it is not
   possible for C-Kermit to support every conceivable keyboard under
   every release of every UNIX (or VMS, or ...) product on every
   different kind of computer possibly under all manner of different
   console drivers, even if it had the means to do so.

   In technical terms, C-Kermit uses the read() function to read
   keystrokes, and read() returns a single byte (value 0 through 255).
   C-Kermit's SET KEY function applies to these single-byte codes.
   "Extended function" keys, such as F-keys, arrow keys, etc, usually
   return either a 2-byte "scan code" or else a character string (such as
   an escape sequence like "<ESC> O p"). In both cases, C-Kermit has no
   way to tell the difference between such multibyte key values, and the
   corresponding series of single-byte key values. This could only be
   done by accessing the keyboard at a much lower level in a highly
   platform-dependent manner, probably requiring tens of thousands of
   lines of code to support even a sampling of the most popular
   workstation / OS combinations.

   However, most workstation console drivers (terminal emulation windows,
   etc) include their own key-mapping facility. For example in AIX, the
   AIXterm program (in whose window you would run C-Kermit) allows
   rebinding of the F1-F12 keys to arbitrary strings. The same is true of
   Xterm and DECterm windows, etc. Consult the technical documentation
   for your workstation or emulator. See sample Xterm (Xmodmap) mappings
   in the [68]Unix C-Kermit Hints and Tips document.

   The SET KEY command (except in Kermit 95) does not allow a key
   definition to be (or contain) the NUL (\0) character.
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  10. FILE TRANSFER

   [ [69]Top ] [ [70]Contents ] [ [71]Next ] [ [72]Previous ]

   C-Kermit 7.0 is the first release of C-Kermit to use fast (rather than
   robust and therefore slow) protocol defaults: long packets, sliding
   windows, control-character unprefixing, and streaming where possible.
   This makes most transfers (partner willing) dramatically faster "out
   of the box" but might break some combinations that worked before. If
   transfers with C-Kermit 7.0 or later fail where transfers worked with
   earlier C-Kermit versions, try the following (one at a time, in this
   order):

    1. SET PREFIXING ALL: Disables control-character unprefixing.
    2. SET STREAMING OFF: Disables streaming.
    3. CAUTIOUS: Selects medium but cautious protocol settings.
    4. ROBUST: this command reverts to the most conservative protocol
       settings.

   Execution of multiple file transfers by C-Kermit from a command file
   when in remote mode might exhibit long delays between each transfer.
   To avoid this, just include the command "SET DELAY 0" in your command
   file before any of the file-transfer commands.

   File transfer failures can occur for all sorts of reasons, most of
   them listed in Chapter 10 of [73]Using C-Kermit. The following
   sections touch on some that aren't.

   The [74]C-Kermit 7.0 Release Notes document SEND /COMMAND as taking an
   argument, but it doesn't. Instead of SEND /COMMAND:{some command},
   use:

SEND /COMMAND [ other switches such as /AS-NAME: ] command [ arguments... ]

  10.1. Laptops

   Watch out for laptops and their assorted power-saver features; for
   example, a built-in modem's "auto timeout delay" hanging up the
   connection in the middle of a file transfer. Most modems, even if they
   have this feature, do not have it enabled by default. But if you
   experience otherwise inexplicable disconnections in the midst of your
   Kermit sessions, check the modem manual for such things as "idle
   timeout", "auto timeout", etc, and add the command to disable this
   feature to Kermit's init string for this modem.

  10.2. NFS

   If uploading a large file to an NFS-mounted disk fails (or is
   painfully slow), try uploading it to a local disk (e.g. /tmp on Unix)
   and then copying to the NFS disk later.

  10.3. Modems

   If you are dialing out and find that downloads work but uploads don't,
   try again with a lower serial-port speed. Case in point: dialing out
   on a certain PC from Linux at 115200 bps using a USR Courier 56K
   "V.Everything" external modem and RTS/CTS flow control. Downloads
   worked flawlessly, uploads stopped dead after the first few packets
   were sent. The modem lights showed constant retraining (ARQ light
   blinks slowly), and the CTS light was off 95% of the time, allowing
   nothing to get through. Reducing the serial port speed to 57600 bps
   made the problems go away. Evidently the PC in question has a very
   fast serial port, since dialing the same modem with a different PC at
   115200 bps works without incident.

  10.4. TCP/IP Connections

   If you have trouble transferring files over a TCP/IP connection, tell
   Kermit to SET PARITY SPACE and try again. If that doesn't work, also
   try a shorter packet length or smaller window size (to compensate for
   certain well-known broken Telnet servers), and/or SET RELIABLE OFF.

  10.5. Multihop Connections

   If you have a multihop connection, with the interior nodes in CONNECT
   mode (Kermit, Telnet, Rlogin, or any other), you can expect (a) file
   transfer to be slower, and (b) the connection to be less transparent
   (to control characters, perhaps to the 8th bit) than a more direct
   connection. C-Kermit 7.0 and later have a "-0" (dash-zero)
   command-line option to make it 100% transparent in cases where it is
   to be used in the middle.

  10.6. Recovery

   The recovery feature (RESEND command) that was added in version
   5A(190) works only for binary-mode transfers. In order for this
   feature to be useful at all, the default for SET FILE INCOMPLETE was
   changed from DISCARD to KEEP. Otherwise an interrupted transfer would
   leave no partial file behind unless you had remembered to change the
   default. But now you have to pay closer attention to Kermit's messages
   to know whether a transfer succeeded or failed -- previously, if it
   failed, the file would not show up on the receiving end at all; in
   5A(190) and later, you'll get a partial file which could easily be
   mistaken for the complete file unless you change the default back to
   DISCARD or read the screen messages, or keep a transaction log.

  10.7. Filename Collisions

   SET FILE COLLISION BACKUP is the default. This means:

     * If you send the same file lots of times, there will be many backup
       files. There is no automatic mechanism within Kermit to delete
       them, no notion of a "version retention count", etc, but you can
       use the PURGE command to clean them up.
     * If a file arrives that has the same name as a directory, the file
       transfer fails because Kermit will not rename a directory. Send
       the file with another name, or use SET FILE COLLISION RENAME.
     * If the directory lacks write permission, the file transfer fails
       even if you have write access to the file that is being backed up;
       in that case, switch to SET FILE COLLISION OVERWRITE or APPEND, or
       send to a different directory.

   SET FILE COLLISION UPDATE depends on the date/time stamp in the
   attribute packet. However, this is recorded in local time, not
   Universal Time (GMT), and there is no indication of time zone. The
   time is expressed to the precision of 1 second, but some file systems
   do not record with this precision -- for example, MS-DOS records the
   file date/time only to the nearest 2 seconds. This might cause update
   operations to send more files than necessary.

   (This paragraph does NOT apply to UNIX, where, as of C-Kermit 7.0,
   C-Kermit pipes incoming mail and print material directly the mail or
   print program): When C-Kermit is receiving files from another Kermit
   program that has been given the MAIL or REMOTE PRINT command, C-Kermit
   follows the current filename collision action. This can be
   disconcerting if the action was (for example) BACKUP, because the
   existing file will be renamed, and the new file will be mailed (or
   printed) and then deleted. Kermit cannot temporarily change to RENAME
   because the file collision action occurs when the filename packet is
   received, and the PRINT or MAIL disposition only comes later, in the
   Attribute packet.

   Watch out for SET FILE COLLISION RENAME, especially when used in
   conjunction with recovery. Recall that this option (which is NOT the
   default) renames the incoming file if a file already exists with the
   same name (the default is to rename the previously existing file, and
   store the incoming file with its own name). It is strongly recommended
   that you do not use SET FILE COLLISION RENAME if you ever intend to
   use the recovery feature:

     * When the file is first received by C-Kermit, its name is changed
       if another file already has the same name. When you RESEND the
       same file after a failure, C-Kermit will probably try to append
       the re-sent portion to the wrong file.
     * Assuming that you get RESEND to work with FILE COLLISION RENAME,
       C-Kermit, when receiving the remainder of the file during a RESEND
       operation, will report back the wrong name. Nothing can be done
       about this because the name is reported back before the receiving
       Kermit program finds out that it is a recovery operation.

   Also watch out for DISABLE DELETE, since this implicitly sets FILE
   COLLISION to RENAME. And note tht DELETE is DISABLEd automatically any
   time you Kermit is in local mode (i.e. it makes a connection). Also
   note that for purposes of DISABLE and ENABLE, "set host *" connections
   do not count as local mode even though, strictly speaking, they are.

  10.8. DOS Pathnames

   When referring to foreign MS-DOS, Windows, Atari ST, OS/2, or other
   file specifications that contain backslash characters in a C-Kermit
   command, you might have to double each backslash, for example:

  C-Kermit>get c:\\directory\\foo.txt

   This is because backslash is used in C-Kermit commands for introducing
   special character codes, variables, functions, etc.

  10.9. Cancellation

   If attempting to cancel local-mode file reception at a very early
   stage (i.e. before data packets are exchanged) with X or Z does not
   work, use E or Ctrl-C instead, or wait until the first data packets
   are sent.

   If you cancel a transfer that is underway using X or Z, and a lot of
   window slots are in use, it might take a while for the cancellation to
   take effect, especially if you do this on the receiving end; that's
   because a lot of packets might already be on their way to you. In that
   case, just be patient and let Kermit "drain" them.

   If C-Kermit is sending a file, remote-mode packet-mode breakout (three
   consecutive Ctrl-C's by default) is not effective until after C-Kermit
   sends its first packet. If C-Kermit is receiving a file or is in
   server mode, it is effective right away. In the former case, the SET
   DELAY value determines the earliest time at which you can break out of
   packet mode.

  10.10. Partner Peculiarities

   When one or both partners is on an SCO operating system such as OSR5,
   you might issue the command:

mapchan -n

   to disable character-set conversion by the terminal driver. Similarly
   for AIX:

setmaps -t NOMAP

   When using C-Kermit to transfer files with the HP48SX calculator, you
   must SET FLOW NONE. The HP48SX does not support flow control, and
   evidently also becomes confused if you attempt to use it. You might
   also need to use SET SEND PAUSE 100 (or other number). For greater
   detail about transferring files the the HP-48, see:

  [75]http://www.columbia.edu/kermit/hp48.html

   Some communication programs have errors in their implementation of
   Kermit attribute packets. If you get an error message from your
   communication program like "Attribute error", tell C-Kermit to SET
   ATTRIBUTES OFF. Better yet, switch to a real Kermit program.

   Some communication software claims to implement Kermit sliding
   windows, but does so incorrectly. If sliding window transfers fail,
   set C-Kermit's window size to the smallest one that works, for
   example, SET WINDOW 1.

   For lots more detail about how to cope with defective Kermit partners,
   see:

     * [76]Coping with Faulty Kermit Implementations (C-Kermit 7.0 and
       later).
     * [77]Coping with Broken Kermit Partners (C-Kermit 8.0 and later).

   The UNIX version of C-Kermit discards carriage returns when receiving
   files in text mode. Thus, "bare" carriage returns (sometimes used to
   achieve overstriking) are lost.
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