ckcbwr.txt

C-Kermit源码。是使用串口/Modem和网络通讯的程序

CKCBWR.TXT           "Beware File" for C-Kermit Version 7.0        -*- text -*-

As of C-Kermit version:  7.0.197
This file last updated:  8 February 2000

Authors: Frank da Cruz and Christine M. Gianone, Columbia University.

  Copyright (C) 1985, 2000,
    Trustees of Columbia University in the City of New York.
    All rights reserved.  See the C-Kermit COPYING.TXT file or the
    copyright text in the ckcmai.c module for disclaimer and permissions.

Report problems, suggestions, fixes, etc, to:

  The Kermit Project
  Columbia University
  612 West 115th Street
  New York NY 10025-7799
  USA
  Email: [e-mail]
  Web:   http://www.columbia.edu/kermit/
  News:  comp.protocols.kermit.misc


DOCUMENTATION

  Frank da Cruz and Christine M. Gianone, "Using C-Kermit", Second Edition,
  1997, Digital Press / Butterworth-Heinemann, Woburn, MA, ISBN 1-55558-164-1
  US single-copy price: $44.95; quantity discounts available.  Available in
  computer bookstores or directly from Columbia University:

    The Kermit Project
    Columbia University
    612 West 115th Street
    New York NY  10025-7799  USA
    Telephone: [phone]
    Email: [e-mail]
    Web: http://www.columbia.edu/kermit/

  The CKERMIT2.TXT file contains supplementary info for C-Kermit 7.0 to be
  used until the 3rd edition of the manual is ready.


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 platform-specific "beware file" for each major
system where C-Kermit runs:

  ckubwr.txt - All variations of UNIX: Linux, HP-UX, AIX, SCO, Solaris, etc.
  ckvbwr.txt - Compaq / Digital Equipment Corporation VMS and OpenVMS
  cklbwr.txt - Stratus VOS
  ckdbwr.txt - Data General AOS/VS
  ckmbwr.txt - Apple Macintosh
  ckibwr.txt - Commodore Amiga
  cksbwr.txt - Atari ST
  ck9bwr.txt - Microware OS-9
  ckpbwr.txt - Bell Labs Plan 9

This file contains the following sections:

   (0) BUGS DISCOVERED SINCE C-KERMIT 7.0 WAS RELEASED
   (1) INCOMPATIBLE CHANGES
   (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


(0) BUGS DISCOVERED SINCE C-KERMIT 7.0 WAS RELEASED

The following bugs are known but not yet fixed:

 1. If you try:

      kermit -g <file>

    where file does not exist in the client directory it returns the error:

      FAILURE: No filespec given!

    instead of:

      FAILURE: <file> does not exist.

 2. True ISO 8601 date-time format is not supported: yyyymmddThhmmss
    or yyyymmdd hhmmss.  Kermit supports yyyymmdd_hh:mm:ss.

 3. Log into IKSD
    GET file1 newname
    Switch to the client's command prompt
    SEND file2
    file2 will be stored on IKSD as newname

 4. The new built-in LOGIN command will conflict with any existing LOGIN
    macros.  This is always the case with new commands, but LOGIN is an
    especially likely name for a macro.  To work around, either rename your
    LOGIN macro to something else, or else invoke it with "do login <args>".

 5. If a Hayes-command-set modem has "reset on DTR loss" set (&D3) and
    the modem prints OK upon reset, even when the reset happened because
    of DTR loss, Kermit can become mighty confused, especially after a
    HANGUP command.  Elsa MicroLink modems (a German brand) has this
    peculiarity.  The Kermit bug is that the HANGUP command will drop DTR
    even if you SET MODEM HANGUP-METHOD MODEM-COMMAND, *if* the modem
    command fails.  C-Kermit has always operated this way on the assumption
    that if the user says to HANGUP, the user means it.  However, in this
    case, dropping DTR produces the unexpected OK response, and then all
    future dialog is out of sync.  There is no way for the user to tell 
    C-Kermit NOT to drop DTR under these circumstances.  This will be
    fixed in the next release.

 6. (Not a bug.)  All RENAME operations are performed using the underlying
    system services for renaming a file.  If the underlying system service
    does not allow files to be renamed across disks, these operations fail.
    This includes the RENAME command and SEND, RECEIVE, or GET /MOVE-TO.  This
    might not be clear enough in the documentation.  Note that in UNIX, there
    is no obvious way for a user to tell whether two directories are on the
    same disk.

 7. Various typos and syntax errors in the makefile and source file.  The
    most serious error prevented any and all SCO OSR5 builds from working.
    All these are fixed in C-Kermit 7.0.197, which simply allows builds to
    succeed that didn't in 7.0.196, but which makes no functional changes.

 8. Modem signal detection does not work in SCO OSR5 and Unixware 7.

 9. The new SHIFT command does not decrement \v(argc) if it is used within
    an IF { } or ELSE { } block.

10. The -b command-line option has no effect if given before -l (the order
    of command-line options should not matter; however the current situation
    has always been the case).

11. When C-Kermit translates from (say) Latin-1 to UTF-8, it does not convert
    the C1 bytes.

12. If you TAKE <file> <arg1> <arg2> -- i.e. specify args, then the same args
    remain in effect for the next TAKE command.  This is not really a bug,
    since it's documented, but it's not optimal either, and probably will be
    changed in the next release, so don't depend on this behavior.  In the
    meantime, work around by UNDEF'ing \%1, \%2, ... after any TAKE command
    that includes arguments.

13. The HEBREW7 translation table has a typo.

14. SET TRANSFER CHARACTER-SET TRANSPARENT sets up a garbage translation.
    Workaround: give a SET FILE CHARACTER-SET command afterwards. 

15. Automatic text/binary mode switching via filename patterns should ignore
    pathname prefixes and backup suffixes, but does not.


(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 <remote-name> <local-name>

   or:

     get /as-name:<local-name> <remote-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 ...

See ckermit2.txt Section 0 for additional items and further detail.


(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"

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 between 256 and 4096 characters,
depending on the platform; 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