Columbia Kermit/kermit.zip/old/ckermit60/ckuker.bwr

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CKUKER.BWR         "Beware File" for C-Kermit Version 6.0         -*- text -*-

                 UNIX VERSION

As of C-Kermit version:  6.0.192
This file last updated:  Fri Sep  6 23:23:23 1996

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

  Copyright (C) 1985, 1996, 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.

WHAT IS IN THIS FILE

This is the "beware file" for the UNIX version of C-Kermit.  It contains
hints and tips, frequently asked questions (and answers), troubleshooting
advice, limitations and restrictions, known bugs, etc, that apply to all UNIX
variations, as well as to specific ones like HP-UX, AIX, SunOS, Solaris,
Unixware, NeXTSTEP, etc etc.  It should be read in conjunction with the
system-independent C-Kermit "beware file", ckcker.bwr, which contains similar
information that applies to all versions of C-Kermit (VMS, OS/2, AOS/VS, VOS,
etc, as well as to UNIX).

CONTENTS:

  (0) DOCUMENTATION
  (1) IMPORTANT FILES
  (2) BINARIES
  (3) NOTES ON SPECIFIC UNIX VERSIONS
  (3.1) C-KERMIT AND AIX
  (3.2) C-KERMIT AND HP-UX
  (3.3) C-KERMIT AND LINUX
  (3.4) C-KERMIT AND NEXTSTEP
  (3.5) C-KERMIT AND QNX
  (3.6) C-KERMIT AND SCO UNIX, XENIX, ODT, AND OPENSERVER
  (3.7) C-KERMIT AND SOLARIS
  (3.8) C-KERMIT AND SUNOS
  (3.9) C-KERMIT AND ULTRIX
  (3.10) C-KERMIT AND UNIXWARE
  (3.11) C-KERMIT AND APOLLO SR10
  (3.12) C-KERMIT AND TANDY XENIX 3.0
  (3.13) C-KERMIT AND OSF/1 (DIGITAL UNIX)
  (3.14) C-KERMIT AND SGI IRIX
  (3.15) C-KERMIT AND THE BEBOX
  (4) GENERAL UNIX-SPECIFIC LIMITATIONS AND BUGS
  (5) INITIALIZATION AND COMMAND FILES
  (6) COMMUNICATION SPEED SELECTION
  (7) COMMUNICATIONS AND DIALING
  (8) HARDWARE FLOW CONTROL
  (9) TERMINAL CONNECTION AND KEY MAPPING
  (10) FILE TRANSFER
  (11) EXTERNAL FILE TRANSFER PROTOCOLS
  (11.1) C-KERMIT AS AN EXTERNAL PROTOCOL
  (11.2) INVOKING EXTERNAL PROTOCOLS FROM C-KERMIT
  (11.3) USING C-KERMIT WITH TERM
  (12) MISCELLANEOUS

(0) DOCUMENTATION

C-Kermit is documented in the book "Using C-Kermit" by Frank da Cruz and
Christine M. Gianone, Digital Press, Burlington, MA, USA, ISBN 1-55558-164-1.
Price: US $39.95.  To order, call Columbia University, New York City,
at [phone], or Digital Press / Butterworth-Heinemann at:

  [phone]  (Massachusetts office for USA & Canada)
  [phone] (Rushden, England office for Europe)
  [phone]   (Chatswood, NSW, office for Australia & New Zealand)
  [phone]     (Singapore office for Asia)

A German edition is available from Verlag Heinz Heise in Hannover, Germany,
Tel. [phone], Fax. [phone].

New features added since these books were published are documented in the
ckcker.upd file.

TECHNICAL SUPPORT

Please consult the documentation listed above, plus the ckcker.bwr file and
this file itself, before submitting questions, reporting problems, etc, to:

  E-Mail: [e-mail]

    News: comp.protocols.kermit.misc

    Post: The Kermit Project
          Columbia University
          612 West 115th Street
          New York NY  10025-7799
          USA

    Fax: [phone]
     or: [phone]

Telephone support also available:

  USA Only:  [phone], cost: $2.50 per minute
  Anywhere:  [phone], cost: $25.00 per call, payable via Visa or MC.


(1) IMPORTANT FILES

In addition to the published documentation, the following files are useful
in troubleshooting:

    ckaaaa.hlp:  Overview, file naming conventions, list of files, etc.
    ckuins.doc:  Installation instructions for UNIX C-Kermit.
    ckccfg.doc:  C-Kermit program configuration information.
    ckcker.bwr:  C-Kermit "beware file" for all C-Kermit implementations.
    ckuker.bwr:  C-Kermit "beware file" specific to UNIX (this file).
    ckcplm.doc:  C-Kermit program logic manual.
    ckcker.upd:  User documentation for features added since 5A(188).
    ckcXXX.upd:  Program edit history for edit XXX, e.g. ckc190.upd.

(2) BINARIES

It is often dangerous to run a binary C-Kermit (or any other) program built
on a different computer.  Particularly if that computer had a different C
compiler, libraries, operating system version, processor features, etc, and
especially if the program was built with shared libraries.

It is often OK to run a binary built on an earlier OS version, but it is
rarely possible (or safe) to run a binary built on a later one, for example
to run a binary built under SunOS 4.1.2 on a SunOS 4.1.1 system.

When in doubt, build C-Kermit from the source code on the system where it is
to be run (if possible!).  If not, ask us for a binary specific to your
configuration.  We might have one, and if we don't, we might be able to get
one.

(3) NOTES ON SPECIFIC UNIX VERSIONS

The following sections apply to specific UNIX versions.

(3.1) C-KERMIT AND AIX

Many problems reported with bidirectional terminal lines on AIX 3.2.x on the
RS/6000.  Workaround: don't use bidirectional terminal lines, or write some
kind of shell script that turns getty off on the line before starting Kermit,
or before Kermit attempts to do the SET LINE.  (But note: These problems
MIGHT be fixed in C-Kermit 6.0.192.)

Reportedly, all versions of IBM AIX use the same (undocumented) lockfile
conventions as RTAIX.  If this is true, the "makes" for PS/2 AIX and AIX/370
will have to be changed to use the RTAIX convention (it may be sufficient to
simply add -DRTAIX to the make entry).

C-Kermit SET HOST or TELNET from AIX on an RS/6000 to another RS/6000 won't
work right unless you set your local terminal type to something other than
AIXTERM.  When your terminal type is AIXTERM, AIX TELNET sends two escapes
whenever you type one, and the AIX telnet server swallows one of them.
This has something to do with the "hft" device.  This behavior is reportedly
removed in AIX 3.2.

Transfer of binary -- and maybe even text -- files can fail on AIX 3.x.  The
problem was traced to a facility in AIX whereby a particular port can have
character-set translation done for it by the tty driver.  The following
advice from a knowledgeable AIX user:

  (begin quote...)  [This feature] has to be checked (and set/cleared) with
  a separate command, unfortunately stty doesn't handle this.  To check:

    $ setmaps
    input map: none installed
    output map: none installed

  If it says anthing other than "none installed" for either one, it is likely
  to cause a problem with kermit.  To get rid of installed maps:

    $ setmaps -t NOMAP

  However, I seem to recall that with some versions of AIX before 3.2.5, only
  root could change the setting.  I'm not sure what versions - it might have
  only been under AIX 3.1 that this was true.  At least with AIX 3.2.5 an
  ordinary user can set or clear the maps.  (...end quote) And this would
  imply that Kermit itself cannot be coded to take care of this, because it
  would have to run as root.  On the same problem, another knowledgeable AIX
  user says:

  The way to get information on the NLS mapping under AIX (3.2.5 anyway) is
  as follows.  From the command line type:

    lsattr -l tty# -a imap -a omap -E -H

  Replace the tty number for the number sign above. This will give a human
  readable output of the settings that looks like this;

    # lsattr -l tty2 -a imap -a omap -E -H
    attribute value description     user_settable

    imap      none  INPUT map file  True
    omap      none  OUTPUT map file True

  If you change the -H to a -O, you get output that can easily be processed
  by another program or a shell script, for example:

    # lsattr -l tty2 -a imap -a omap -E -O
    #imap:omap
    none:none

  To change the settings from the command line, the chdev command is used
  with the following syntax.

    chdev -l tty# -a imap='none' -a omap='none'

  Again substituting the appropriate tty port number for the number sign,
  "none" being the value we want for C-Kermit.  Of course, the above can also
  be changed by using the SMIT utility and selecting devices - tty.
  (...end quote)

(3.2) C-KERMIT AND HP-UX

During the C-Kermit 6.0 Beta cycle, something happened to ckcpro.w (or, more
precisely, the ckcpro.c file that is generated from it) which causes HP
optimizing compilers under HP-UX versions 7.0 and 8.0 (apparently on all
platforms) as well as under HP-UX 9.0 on Motorola platforms only, to blow up.
The symptoms vary from the system grinding to a halt, to the compiler
crashing, to the compilation of the ckcpro.c module taking very long periods
of time, like 9 hours.

On HP-UX 9.0, a kernel parameter, maxdsiz (maximum process data segment size),
seems to be important.  On Motorola systems, it is 16MB by default, whereas on
RISC systems the default is much bigger.  Increasing maxdsiz to about 80MB
seems to make the problem go away, but only if the system also has a lot of
physical memory -- otherwise it swaps itself to death.

Therefore, the C-Kermit 6.0 makefile entries for HP-UX 7.x and 8.x that do
optimization, compile ckcpro.c first without optimization.  For HP-UX 9.0, a
special entry, hpux90mot, was added for Motorola makes; the regular entries
optimize all modules.

Even so, the optimizing compiler will often complain about "some optimizations
skipped" on certain modules, due to lack of space available to the optimizer.
You can always increase the space (the incantation depends on the particular
compiler version -- see the makefile), but doing so tends to make the
compilations take a much longer time.  For example, the "hpux100o+" makefile
entry adds the "+Onolimit" compiler flag, and about an hour to the compile
time on an HP-9000/730.  But it *does* produce an executable that is about
10K smaller :-)

(3.2.0) Performance

An unexpected slowness has been noted when transferring files over local
Ethernet connections when an HP-UX system (9.0 or later, perhaps also earlier
versions) is on the remote end.   The following experiment was conducted to
determine the cause.

The systems were HP-UX 10.00 (on 715/33) and SunOS 4.1.3 (on Sparc-20), both
on the same local 10Mbps Ethernet.  Window size 20, packet length 4096, parity
none, control prefixing "cautious", using only local disks on each machine --
no NFS.  The file was a 1.08MB binary file (wermit), transferred in binary
mode.  Conditions were relatively poor: the Sun and the local net heavily
loaded; the HP system is slow and memory-constrained.

 Client   Server   Send    Receive
  Sun      HP       36       18    <-- K cps
  HP       HP       25       15
  HP       Sun      77       83
  Sun      Sun      60       60

So whenever HP is the server we have bad performance.  Why?

 . Changing file display to CRT has no effect (so it's not the curses
   library on the client side).

 . Changing TCP RECV-BUFFER or SEND-BUFFER has very little effect.

 . Telling the client to make a binary-mode connection (SET TELNET BINARY
   REQUESTED, which successfully negotiates a binary connection) has no effect.

BUT...  If I start C-Kermit as a TCP server:

  set host * 3000
  server

and then from the client "set host blah 3000", I get:

 Client   Server   Send    Receive
  HP       HP       50       50
  Sun      HP       77       67
  HP       Sun      57       85
  Sun      Sun      57       50

Therefore the HP-UX telnet server or pty driver seems to be adding more
overhead than the SunOS one, and most others.  When going through this type of
connection (a remote telnet server) there is nothing Kermit can do improve
matters, since the telnet server and pty driver are between the two Kermits,
and neither Kermit can have any influence over them (except putting the Telnet
connection in binary mode, but that doesn't help).

(3.2.1) HP-UX 5.21

Reportedly, "[there is] a bug in C-Kermit using HP-UX version 5.21 on the
HP-9000 series 500 computers.  It only occurs when the controlling terminal
is using an HP-27140 six-port modem mux.  The problem is not present if the
controlling terminal is logged into an HP-27130 eight-port mux.  The symptom
is that just after dialing successfully and connecting Kermit locks up and
the port is unusable until both forks of Kermit and the login shell are
killed."

(3.2.2) HP-UX 8.05

To make C-Kermit work on HP-UX 8.05 on a model 720, obtain and install HP-UX
patch PHNE_0899.  This patch deals with a lot of driver issues, particularly
related to communication at higher speeds.

(3.2.3) HP-UX 9.00 AND LATER

HP-UX 9.00 and 9.01 need patch PHNE_3641 for hptt0.o, asio0.o, and ttycomn.o
in libhp-ux.a.  Contact Hewlett Packard if you need this patch.  Without it,
the dialout device (tty) will be hung after first use; subsequent attempts to
use will return an error like "device busy".

C-Kermit works fine -- including its curses-based file-transfer display -- on
the console terminal, in a remote session (e.g. when logged in to the HP 9000
on a terminal port or when telnetted or rlogin'd), and in an HP-VUE hpterm
window or an xterm window.

Before you can use serial ports on the HP-9000, you must configure them as
either "terminals" or "modems" with SAM ("peripheral devices"..."terminals and
modems"), as described in the HP manual, "Configuring HP-UX for Peripherals:
HP 9000".  If you attempt to use a serial device before it has been configured
this way, it will not work properly; typical symptoms are (a) no communication
at all; (b) nonfunctional modem signals; and/or (c) massive amounts of
character loss in both directions.

In HP-UX 9.0, serial device names were different between HP9000 Series 700 and
Series 800 systems.  In 10.0, device file names (and also major and minor
numbers) have "converged", as shown in the following table:

  Converged HP-UX Serial I/O Filenames : TTY Mux Naming
  ---------------------------------------------------------------------
  General meaning        S800 9.0          S700 9.0    Convio 10.0
  ---------------------------------------------------------------------
  tty* hardwired ports   tty<X>p<Y>        tty<YY>     tty<D>p<p>
             diag:mux<X>                   diag:mux<D>
  ---------------------------------------------------------------------
  ttyd* dial-in modems   ttyd<X>p<Y>       ttyd<YY>    ttyd<D>p<p>
             diag:ttyd<X>p<Y>              diag:ttyd<D>p<p>
  ---------------------------------------------------------------------
  cua* auto-dial out     cua<X>p<Y>        cua<YY>     cua<D>p<p>
             diag:cua<X>p<Y>
  ---------------------------------------------------------------------
  cul* dial-out          cul<X>p<Y>        cul<YY>     cul<D>p<p>
             diag:cul<X>p<Y>
  ---------------------------------------------------------------------
   <X>= LU (Logical Unit)  <D>= Devspec (decimal card instance)
   <Y> or <YY> = Port      <p>= Port

For dialing out, you should use the cua or cul devices.  When C-Kermit's
CARRIER setting is AUTO or ON, C-Kermit will pop back to its prompt
automatically if the carrier signal drops, e.g. when you log out from the
remote computer or service.  If you use the tty<D>p<d> (e.g. tty0p0) device,
the carrier signal is ignored.  The tty<D>p<d> device should be used for
direct connections where the carrier signal does not follow RS-232
conventions (use the cul device for hardwired connections through a true null
modem).  Do not use the ttyd<D>p<d> device for dialing out.

Kermit's access to serial devices is controlled by "UUCP lockfiles", which are
intended to prevent different users using different software programs (Kermit,
cu, etc, and UUCP itself) from accessing the same serial device at the same
time.  When a device is in use by a particular user, a file with a special
name is created in the /var/spool/locks directory.  The file's name indicates
the device that is in use, and its contents indicates the process ID (pid) of
the process that is using the device.  Since serial devices and the
/var/spool/locks directory are not both publicly readable and writable, Kermit
and other communication software must be installed setuid to the owner (bin)
of the serial device and setgid to the group (daemon) of the /var/spool/locks
directory.  Kermit's setuid and setgid privileges are enabled only when
opening the device and accessing the lockfiles.

Let's say "unit" means a string of decimal digits (the interface instance
number) followed by the letter "p" (lowercase), followed by another string of
decimal digits (the port number on the interface), e.g. "0p0", "0p1", "1p0",
etc.  Then a normal serial device (driver) name consists of a prefix ("tty",
"ttyd", "cua", "cul") followed by a unit, e.g. "cua0p0".  Kermit's treatment
of UUCP lockfiles is as close as possible to that of the HP-UX "cu" program.
Here is a table of the lockfiles that Kermit creates for unit 0p0:

  Selection      Lockfile 1     Lockfile 2
  ------------   ------------   ------------
  /dev/tty0p0    LCK..tty0p0    (none)
* /dev/ttyd0p0   LCK..ttyd0p0   (none)
  /dev/cua0p0    LCK..cua0p0    LCK..ttyd0p0
  /dev/cul0p0    LCK..cul0p0    LCK..ttyd0p0
  <other>        LCK..<other>   (none)

(* = Dialin device, should not be used.)

The final case allows for symbolic links, etc, but, of course, it is not
foolproof since we have no way of telling which device is really being used.

When Kermit tries to open a dialout device whose name ends with a "unit", it
searches the lockfile directory for all possible names for the same unit.  For
example, if user selects /dev/cul2p3, Kermit looks for lockfiles named
LCK..tty2p3, LCK..ttyd2p3, LCK..cua2p3, and LCK..cul2p3.

If any of these files are found, Kermit opens them to find out the ID (pid) of
the process that created them; if the pid is still valid, the process is still
active, and so the SET LINE command fails and the user is informed of the pid
so s/he can use "ps" to find out who is using the device.

If the pid is not valid, the file is deleted.  If all such files (i.e. with
same "unit" designation) are successfully removed, then the SET LINE command
succeeds; up to four messages are printed telling the user which "stale
lockfiles" are being removed.

If the selected device was in use by "cu", Kermit can't open it, because "cu"
has changed its ownership, so we never get as far as looking at the lockfiles.
In the normal case, we can't even look at the device to see who the owner is
because it is visible only to its (present) owner.  In this case, Kermit says
(for example):

  /dev/cua0p0: Permission denied

When Kermit releases a device it has successfully opened, it removes all the
lockfiles that it created.  This also happens whenever Kermit exits "under its
own power".

If Kermit is killed with a device open, the lockfile(s) are left behind.  The
next Kermit program that tries to assign the device, under any of its various
names, will automatically clean up the stale lockfiles because the pids
they contain are invalid.

(3.2.4) HP-UX 10.10 AND LATER

C-Kermit is included as part of the HP-UX 10.xx operating system by contract
between Hewlett Packard and Columbia University.  Each level of HP-UX 10.xx
includes a freshly built C-Kermit binary in /bin/kermit, which should work
correctly.  However, if you are building your own or downloading from
Columbia, you should be aware that you can only use a binary that was built
under the same OS level as you are running.  As of C-Kermit version 6.0, HP-UX
10.xx binaries announce, in the startup herald and the VERSION command, the
explicit HP-UX version they were built for: HP-UX 10.00, 10.10, 10.20, or
10.30.  If there is a version mismatch, HP-UX does something like "Invalid
version for shared lib /usr/lib/libc.1, IOT trap (core dumped)".

Beginning in 10.10, libcurses is linked to libxcurses, the new UNIX95 (X/Open)
version of curses, which has some serious bugs; some routines, when called,
would hang and never return, some would dump core.  Evidently libxcurses
contains a select() routine, and whenever C-Kermit calls what it thinks is the
regular (sockets) select(), it gets the curses one, causing a segmentation
fault.  There is a patch for this from HP, PHCO_8086, "s700_800 10.10
libcurses patch", "shared lib curses program hangs on 10.10", "10.10 enhanced
X/Open curses core dumps due to using wrong select call", 96/08/02 (you can
tell if the patch is installed with "what /usr/lib/libxcurses.1"; the unpatched
version is 76.20, the patched one is 76.20.1.2.  It has been verified that
C-Kermit works OK with the patched library, but results are not definite for
HP-UX 10.20 or higher.

To ensure that C-Kermit works even on non-patched HP-UX 10.10 systems,
separate makefile entries are provided for HP-UX 10.00/10.01, 10.10, 10.20,
etc, in which the entries for 10.10 and above link with libHcurses, which is
"HP curses", the one that was used in 10.00/10.01.

(3.3) C-KERMIT AND LINUX

Be sure to read the comments in the "linux:" makefile entry.  There are all
sorts of confusing issues caused by the many and varied Linux distributions.
Some of the worst involve the curses library and header files: where are they,
what are they called, which ones are they really?  Ditto for UUCP lock files.

Run C-Kermit in the regular console screen, which provides VT100 emulation via
the "console" termcap entry, or under X-Windows in an xterm window.  Before
starting C-Kermit in an xterm window, tell the xterm window's shell to "stty
sane".

How to set up your PC console keyboard to send VT220 key sequences when using
C-Kermit as your communications program in an X terminal window: Create a file
somewhere (e.g. in /root/) called .xmodmaprc, containing something like the
following:

  keycode 77  = KP_F1       ! Num Lock     => DEC Gold (PF1)
  keycode 112 = KP_F2       ! Keypad /     => DEC PF1
  keycode 63  = KP_F3       ! Keypad *     => DEC PF3
  keycode 82  = KP_F4       ! Keypad -     => DEC PF4
  keycode 111 = Help        ! Print Screen => DEC Help
  keycode 78  = F16         ! Scroll Lock  => DEC Do
  keycode 110 = F16         ! Pause        => DEC Do
  keycode 106 = Find        ! Insert       => DEC Find
  keycode 97  = Insert      ! Home         => DEC Insert
  keycode 99  = 0x1000ff00  ! Page Up      => DEC Remove
  keycode 107 = Select      ! Delete       => DEC Select
  keycode 103 = Page_Up     ! End          => DEC Prev Screen
  keycode 22  = Delete      ! Backspace sends Delete (127)

Then put "xmodmap <filename>" in your .xinitrc file (in your login
directory), e.g.

  xmodmap /root/.xmodmaprc

Of course you can move things around.  Use the xev program to find out key
codes.

Different UUCP lockfile conventions are used by Linux, depending on your Linux
distribution.  In C-Kermit 6.0, "make linux" uses /var/lock/LCK..name, decimal
ASCII 10-byte PID string with leading spaces because -DLINUXFSSTND ("Linux File
System Standard") is included in the compilation CFLAGS.  If you remove this
definition, C-Kermit will use the earlier arrangement of integer PID,
/usr/spool/uucp/LCK..name.  The leading spaces are required by FSSTND 1.2, but
FSSTND 1.0 required leading zeros; to get the leading zeros, also include
-DFSSTND10.  Use whichever option agrees with your uucp, cu, tip, etc,
programs.

Building C-Kermit on Linux 1.1.33 and 1.1.34 gets fatal compilation errors
due to inconsistencies in the Linux header files.  Linux kernel versions prior
to 1.1.33 and later than 1.1.34 should be OK.

C-Kermit versions prior to 5A(190) did not support hardware flow control or
high interface speeds for Linux.

One Linux user reported problems dialing out using the /dev/cua device;
"device busy" errors.  He said that using the alternative name (driver) for
the device, /dev/ttyS2, made the problem go away.

Reportedly there is a bug in gcc 2.5.8 with signed to unsigned compares
that can wreak havoc when Kermit (or most any other program) is compiled with
this version of gcc; reportedly this can be worked around, at least in part,
by adding "-fno-unroll-loops" to the gcc compilation options.

Reportedly, if you have the iBCS2 (Intel Binary Compatibility Standard 2)
module installed, you can also run SCO Xenix and UNIX binaries under Linux,
including the SCO C-Kermit binaries, shareable libraries and all.
(iCBS2 is available via anonymous ftp from tsx-11.mit.edu, along with an
SCO libc_s compatibility module for Linux).

Some Linux users reported that after doing a file transfer using the
fullscreen display (thermometer), that "screen scrolling locks up" and the
cursor "is stuck on the bottom of the screen".  This probably only happens
when using the console device.  This turns out to be a problem with Linux
ncurses.  The workaround is to use "set file display crt" or "serial".  The
cure (reportedly) is to build C-Kermit with Linux ncurses 1.8.7 (or later).

(Time passes...)  Now (early 1996) we have increasing reports of C-Kermit core
dumping in Linux 1.2.x, e.g. when the "set line" command is given.  But they
are conflicting -- it happens to some people, not to others.  Not much can be
said about this but:

From: [e-mail] (Frank da Cruz)
Newsgroups: comp.protocols.kermit.misc
Subject: Re: Kermit drops core at SET LINE /dev/cua1
Date: 14 Feb 1996 15:43:07 GMT
Organization: Columbia University

In article <4fr2nc$[e-mail]>,
Branden Robinson <[e-mail]> wrote:
: I'm trying to run C-Kermit under Linux, but as soon as I type "set line
: /dev/cua1", kermit gets a segmentation fault.  This is the correct line, as
: evidenced by the fact that "echo ATDT" and a phone number redirected to
: /dev/cua1 makes the modem dial.
:
: I thought this might have something to do with the lock file put on
: /dev/cua1, but both the compliation with the -DLINUXFSSTND and without it
: yield the same result.  What is going on here?
:
: Relevant hardware:
:  Hayes Accura 14.4 + FAX internal on COM 2
:
: Relevant software:
:  Linux Debian 0.93R6, kernel 1.2.13, GCC 2.6.3, C-kermit 1.90
:
C-Kermit 5A(190) was tested successfully on every known Linux variation at
the time it was released (October 1994), but since then what is
collectively known as Linux has been changing rapidly out from underneath
us, thanks in large part to its numerous repackagers.  Most of the
problems stem from the many and varied curses libraries; this is the first
report I have heard of this nature.  You might try:

 1. The Debian C-Kermit distribution, put together and tested by the
    Debian Project.  Maybe they linked it with different libraries than
    you did:

      ftp://kermit.columbia.edu/kermit/linux/

 2. The 6.0.192 Alpha not-yet-a-release:

      ftp://kermit.columbia.edu/kermit/test/

 3. Taking a debug log of a core-dumping session and sending the last
    hundred lines or so to [e-mail] for analysis.  Also see if
    you can get a backtrace from the core file to find out what routine it
    was in when it faulted.  I don't know what the command for this is on
    Linux -- locally I use "adb kermit core" and then "$c", where "kermit"
    is Kermit's pathname and "core" is the core file's pathname.

[e-mail] (John D. Griffith) replies:
Well I am succesfully using C-kermit 1.90 with the same modem on
/dev/cua2 (COM3).  I am running linux 1.2.13 (a.out) and gcc 2.5.8.
My distribution was originally Red Hat Release 1.0, but has been
considerably customized since then.

[e-mail] (Bill Mitchell) replies:
I'm the debian kermit maintainer, but I'm afraid I don't have much
of a clue about this.  The debian kermit sources are stock kermit
sources except for the addition of some debian-specific files (debian.*)
which don't impact non-debian compilation and the addition of a debian
target in debian.makefile.
I use kermit regularly on my debian linux system with the 1.2.13 kernel,
and my modem is on /dev/cua1.

And in the same vein...

Date: Wed, 15 Nov 95 10:16:24 EST
From: Frank da Cruz <[e-mail]>
To: kurt klingbeil <[e-mail]>
Subject: Re: cku190 & linux 1.1.59 vs 1.2.x ??
In-Reply-To: Your message of Tue, 14 Nov 1995 23:57:21 -0700 (MST)

> Any idea what's changed in the serial handling of linux
> between 1.1.x and 1.2.x ?
>
Absolutely no idea.  It's just the way of the world.  The rule is that if
Kermit works in release n of any operating system, then release n+1 breaks it.
I think this must be an internal requirement for OS developers.  The nice
thing about Linux is you don't even know who to ask about it.

> Using cku190 to connect to a USR v.everything (no getty or any other process
> active on that tty port):
> I can dial, connect, run a remote session.
> When I hangup, the loss of CD causes kermit
> to disconnect, drop RTS and DTR, and return to its prompt.
>
> When attempting to immediately re-connect to the modem
> (using c command), I can see the DTR and RTS lines being brought up:
> (The modem's CTS and DSR remain set at all times.)
>
> Under Linux 1.1.59, kermit is immediately able to communincate with
> the modem.  Under Linux 1.2.{3,8,13} kermit appears to be hung -
> no modem responses are received, kermit ignores it's escape character
> and will wait forever.  If one sends kermit a signal (either via kill,
> or, if one is on the console via break (control-C is ignored as well)),
> then a few characters of garbage appear in kermit's session, and
> things are back to normal.
>
> I suspect that either a previously non-blocking read is now a blocking
> read, or that previously the port was being properly flushed before
> a connection was made, and that under 1.2.x it isn't and hence kermit
> gets deadlocked waiting forever for a conidition which never occurs.
>
> Any ideas ?
>
(Unhelpful response deleted)

Could this be the explanation? --

Date: Sat, 13 Jan 1996 09:48:11 -0800 (PST)
From: John Harris <[e-mail]>
Subject: C-Kermit Installation on Linux 1.2.1

Below is a letter which addresses the problem I was having installing
C-Kermit on a Linux platform.  So you do not need to waste your time
addressing my difficulty, I wish to inform you that I have just resolved
it; that is, the compile now takes place without even a warning.

So that someone else can benefit, I briefly describe the cause of the
problem.  The following directories were not present: /usr/include/linux/
and /usr/src/linux/include/asm.  There may also have been other files
missing in certain directories; for example, /usr/include/linux and
/usr/include/asm.  The problem may have arisen from an oversight during
Linux installation; for example, I may have forgotten to create the file
system in advance of installation with "mke2fs -c <partition> <size>" or
perhaps I simply neglected to transfer some library files during the
software installation itself.

In more recent releases of Linux (mid-1996), the trend is to replace curses by
ncurses.  But of course this is not transparent to application software that
includes curses.h and links with libcurses.  Linus says it *should* be
transparent -- the application should continue to refer to curses and not to
ncurses.  C-Kermit follows this recommendation, so if you have curses-related
trouble during compilation or at runtime, create symbolic links called
curses.h and libcurses.a (or .sa, or .so, or .so.XX, etc) pointing to
ncurses.h and libncurses-dot-whatever, and rebuild Kermit.

Also note that some Linux distributions have internal problems in their header
files.  In one case, there are fatal errors in <termcap.h> that can be fixed
by adding "#include <termios.h>" to the termcap.h file.

See additional comments in the Linux entry in the makefile.

(3.4) C-KERMIT AND NEXTSTEP

Run C-Kermit in a Terminal, Stuart, or xterm window, or when logged in
remotely through a serial port or TELNET connection.  C-Kermit does not work
correctly when invoked directly from the NeXTSTEP File Viewer or Dock.  This
is because the terminal-oriented gtty, stty, & ioctl calls don't work on the
little window that NeXTSTEP pops up for non-NeXTSTEP applications like Kermit.
CBREAK and No-ECHO settings do not take effect in the command parser --
commands are parsed strictly line at a time.  "set line /dev/cua" works.
During CONNECT mode, the console stays in cooked mode, so characters are not
transmitted until carriage return or linefeed is typed, and you can't escape
back.  If you want to run Kermit directly from the File Viewer, then launch it
from a shell script that puts it in the desired kind of window, something like
this (for "Terminal"):

  Terminal -Lines 24 -Columns 80 -WinLocX 100 -WinLocY 100 $FONT $FONTSIZE \
  -SourceDotLogin -Shell /usr/local/bin/kermit &

C-Kermit does not work correctly on a NeXT with NeXTSTEP 3.0 to which you have
established an rlogin connection, due to a bug in NeXTSTEP 3.0, which has been
reported to NeXT.

The SET CARRIER command has no effect on the NeXT -- this is a limitation of
the tty device drivers.

Hardware flow control on the NeXT is selected not by "set flow rts/cts" in
Kermit (since NeXTSTEP offers no API for this), but rather, by using a
specially-named driver for the serial device: /dev/cufa instead /dev/cua;
/dev/cufb instead of /dev/cub.  This is available only on 68040-based NeXT
models (the situation for Intel NeXTSTEP implementations is unknown).

NeXT-built 68030 and 68040 models have different kinds of serial interfaces;
the 68030 has a Macintosh-like RS-422 interface, which lacks RTS and CTS
signals; the 68040 has an RS-423 (RS-232 compatible) interface, which
supports the commonly-used modem signals.  WARNING: the connectors look
exactly the same, but the pins are used in completely DIFFERENT ways --
different cables are required for the two kinds of interfaces.

  IF YOU GET LOTS OF RETRANSMISSIONS during file transfer, even when
  using a /dev/cuf* device and the modem is correctly configured for
  RTS/CTS flow control, YOU PROBABLY HAVE THE WRONG KIND OF CABLE.

On the NeXT, Kermit reportedly (by TimeMon) causes the kernel to use a lot of
CPU time when using a "set line" connection.  That's because there is no DMA
channel for the NeXT serial port, so the port must interrupt the kernel for
each character in or out.

One user reported trouble running C-Kermit on a NeXT from within NeXT's
Subprocess class under NeXTstep 3.0, and/or when rlogin'd from one NeXT to
another: Error opening /dev/tty:, congm: No such device or address.
Diagnosis: Bug in NeXTSTEP 3.0, cure unknown.

(3.5) C-KERMIT AND QNX

Support for QNX 4.x was added in C-Kermit 5A(190).  This is a full-function
implementation, thoroughly tested on QNX 4.21, and verified to work in both
16-bit and 32-bit versions.  Most advanced features are supported including
TCP/IP, high serial speeds, hardware flow-control, modem-signal awareness,
curses support, etc.

Dialout devices are normally /dev/ser1, /dev/ser2, ..., and can be opened
explicitly with SET LINE.  Reportedly, "/dev/ser" (no unit number) opens the
first available /dev/ser<n> device.

Like all other UNIX C-Kermit implementations, QNX C-Kermit does not provide
any kind of terminal emulation.  Terminal specific functions are provided by
your terminal, terminal window (e.g. QNX Terminal or xterm), or emulator.

QNX C-Kermit, as distributed, does not include support for UUCP line-locking;
the QNX makefile entries (qnx32 and qnx16) include the -DNOUUCP switch.  This
is because QNX, as distributed, does not include UUCP, and its own
communications software (e.g. qterm) does not use UUCP line locking.  If you
have a UUCP product installed on your QNX system, remove the -DNOUUCP switch
from the makefile entry and rebuild.  Then check to see that Kermit's UUCP
lockfile conventions are the same as those of your UUCP package; if not, read
the UUCP lockfile section ckuins.doc and make the necessary changes to the
makefile entry (e.g. add -DHDBUUCP).

BUG: The fullscreen file transfer display works fine the first time, but it is
fractured on subsequent file transfers.  Cause and cure unknown.

(3.6) C-KERMIT AND SCO UNIX, XENIX, ODT, AND OPENSERVER

There is all sorts of confusion among SCO versions, particularly when third-
party communications boards and drivers are installed, regarding lockfile
naming conventions.  Basically, all bets are off if you are using a third
party multiport board.  At least you have the source code.  Hopefully you also
have a C compiler :-)

Use SCO-provided utilities for switching the directionality of a modem line,
such as "enable" and "disable" commands.  For example, to dial out on tty1a,
which is normally set up for logins:

  disable tty1a
  kermit -l /dev/tty1a
  enable tty1a

In SCO Xenix, you must use SET CARRIER ON *and* use the upper-case tty device
name in order to have carrier detection.  SET CARRIER OFF should work with
either upper or lowercase tty devices.  SET CARRIER AUTO is the same as OFF.

SCO Xenix and UNIX can provide different names for the same device.  In Xenix,
/dev/tty1a refers to a terminal device that has no modem control; open, read,
write, and close operations do not depend on carrier.  On the other hand,
/dev/tty1A (same name, but with final letter upper case), is the same device
with modem control, in which carrier is required (the SET LINE command does
not complete until carrier appears, read/write operations fail if there is no
carrier, etc).  In the SCO case, C-Kermit always uses the lowercase name when
creating the UUCP lockfile (this is, according to SCO experts, the proper
behavior, but reportedly not all other communications applications found on
SCO systems follow this rule).

One user of C-Kermit 5A(190) on SCO UNIX 3.2.4 reported that C-Kermit dumps
core when receiving files in local mode.  The crash invariably occurs when the
16384th byte arrives, obviously indicating some kind of int/long, or
short/int, or similar mismatch in argument-passing -- no doubt the byte count.
Other users of SCO UNIX 3.2.4, built using the same makefile entry, report
that they can receive files of any length with no problem at all.  Maybe it
depends on which file transfer display is being used?  If this happens to you,
try using a different file transfer display (SET FILE DISPLAY NONE, SERIAL,
CRT, or FULLSCREEN).

SCO users report that only one copy of Kermit can run at a time when a
Stallion Technologies multiport boards are installed.

(3.7) C-KERMIT AND SOLARIS

The built-in SunLink X.25 support for Solaris 2.3/2.4./25 and SunLink 8.01 or
9.00 works OK provided the X.25 system has been installed and initialized
properly.  Packet sizes might need to be reduced to 256, maybe even less,
depending on the configuration of the X.25 installation.  On one connection
where C-Kermit 6.0 was tested, very large packets and window sizes could be
used in one direction, but only very small ones would work in the other.

In any case, according to Sun, C-Kermit's X.25 support is superfluous with
SunLink 8.x / Solaris 2.3.  Quoting an anonymous Sun engineer:

  ... there is now no need to include any X.25 code within kermit.  As of
  X.25 8.0.1 we support the use of kermit, uucp and similar protocols over
  devices of type /dev/xty.  This facility was there in 8.0, and should
  also work on the 8.0 release if patch 101524 is applied, but I'm not 100%
  sure it will work in all cases, which is why we only claim support from
  8.0.1 onwards.

  When configuring X.25, on the "Advanced Configuration->Parameters" screen
  of the x25tool you can select a number of XTY devices.  If you set this
  to be > 1, press Apply, and reboot, you will get a number of /dev/xty
  entries created.

  Ignore /dev/xty0, it is a special case.  All the others can be used exactly
  as if they were a serial line (e.g. /dev/tty) connected to a modem, except
  that instead of using Hayes-style commands, you use PAD commands.

  From kermit you can do a 'set line' command to, say, /dev/xty1, then set
  your dialing command to be "CALL 12345678", etc.  All the usual PAD
  commands will work (SET, PAR, etc).

  I know of one customer in Australia who is successfully using this, with
  kermit scripts, to manage some X.25-connected switches. He used standard
  kermit, compiled for Solaris 2, with X.25 8.0 xty devices.

C-Kermit can't be compiled successfully under Solaris 2.3 using SUNWspro cc
2.0.1 unless at least some of the following patches are applied to cc (it is
not known which one(s), if any, fix the problem):

  100935-01 SparcCompiler C 2.0.1: bad code generated when addresses
    of two double arguments are involved
  100961-05 SPARCcompilers C 2.0.1: conditional expression with
    function returning strucure gives wrong value
  100974-01 SparcWorks 2.0.1: dbx jumbo patch
  101424-01 SPARCworks 2.0.1 maketool SEGV's instantly on Solaris 2.3

With unpatched cc 2.0.1, the symptom is that certain modules generate
truncated object files, resulting in many unresolved references at link time.

Using a Sun workstation keyboard for VT emulation when accessing VMS:

From: Jerry Leichter <[e-mail]>
Newsgroups: comp.os.vms
Subject: Re: VT100 keyboard mapping to Sun X server
Date: Mon, 19 Aug 1996 12:44:21 -0400

> I am stuck right now using a Sun keyboard (type 5) on systems running SunOS
> and Solaris.  I would like to use EVE on an OpenVMS box with display back to
> the Sun.  Does anyone know of a keyboard mapping (or some other procedure)
> which will allow the Sun keyboard to approximate a VT100/VT220?

You can't get it exactly - because the keypad has one fewer key - but
you can come pretty close.  Here's a set of keydefs I use:

keycode 101=KP_0
keycode 119=KP_1
keycode 120=KP_2
keycode 121=KP_3
keycode 98=KP_4
keycode 99=KP_5
keycode 100=KP_6
keycode 75=KP_7
keycode 76=KP_8
keycode 77=KP_9
keycode 52=KP_F1
keycode 53=KP_F2
keycode 54=KP_F3
keycode 57=KP_Decimal
keycode 28=Left
keycode 29=Right
keycode 30=KP_Separator
keycode 105=KP_F4
keycode 78=KP_Subtract
keycode 8=Left
keycode 10=Right
keycode 32=Up
keycode 33=Down
keycode 97=KP_Enter

Put this in a file - I use "keydefs" in my home directory and feed it
into xmodmap:

  xmodmap - <$HOME/keydefs

This takes care of the arrow keys and the "calculator" key cluster.  The
"+" key will play the role of the DEC "," key.    The Sun "-" key will be
like the DEC "-" key, though it's in a physically different position -
where the DEC PF4 key is.  The PF4 key is ... damn, I'm not sure where
"key 105" is.  I *think* it may be on the leftmost key of the group of
four just above the "calculator" key cluster.

I also execute the following (this is all in my xinitrc file):

xmodmap -e 'keysym KP_Decimal = KP_Decimal'
xmodmap -e 'keysym BackSpace = Delete BackSpace' \
        -e 'keysym Delete = BackSpace Delete'
xmodmap -e 'keysym KP_Decimal = Delete Delete KP_Decimal'
xmodmap -e 'add mod1 = Meta_R'
xmodmap -e 'add mod1 = Meta_L'

Beware of one thing about xmodmap:  Keymap changes are applied to the
*whole workstation*, not just to individual windows.  There is, in fact,
no way I know of to apply them to individual windows.  These definitions
*may* confuse some Unix programs (and/or some Unix users).

If you're using Motif, you may also need to apply bindings at the Motif
level.  If just using xmodmap doesn't work, I can try and dig that stuff
up for you.

(end quote)

  NOTE: The rest of the problems in this section have to do with bidirectional
  tty lines and the Solaris Port Monitor.  Hopefully these are all fixed in
  C-Kermit 6.0.192 Beta.029, 22 Aug 96.

Reportedly, "C-Kermit ... causes a SPARCstation running Solaris 2.3
to panic after the modem connects.  I have tried compiling C-Kermit with Sun's
unbundled C compiler, with GCC Versions 2.4.5 and 2.5.3, with make targets
'sunos51', 'sunos51tcp', 'sunos51gcc', and even 'sys5r4', and each time it
compiles and starts up cleanly, but without fail, as soon as I dial the number
and get a 'CONNECT' message from the modem, I get:

  BAD TRAP
  kermit: Data fault
  kernel read fault at addr=0x45c, pme=0x0
  Sync Error Reg 80 <INVALID>
  ...
  panic: Data Fault.
  ...
  Rebooting...

The same modem works fine for UUCP/tip calling."  Also (reportedly), this only
happens if the dialout port is configured as in/out via admintool.  If it is
configured as out-only, no problem.  This is the same dialing code that works
on hundreds of other System-V based UNIX OS's.  Since it should be impossible
for a user program to crash the operating system, this problem must be chalked
up to a Solaris bug.  Even if you SET CARRIER OFF, CONNECT, and dial manually
by typing ATDTnnnnnnn, the system panics as soon as the modem issues its
CONNECT message.  (Clearly, when you are dialing manually, C-Kermit does not
know a thing about the CONNECT message, and so the panic is almost certainly
caused by the transition of the Carrier Detect (CD) line from off to on.)
This problem was reported by many users, all of whom say that C-Kermit worked
fine on Solaris 2.1 and 2.2.  If the speculation about CD is true, then a
possible workaround might be to configure the modem to leave CD on (or off)
all the time.  Perhaps by the time you read this, a patch will have been
issued for Solaris 2.3.

The following is from Karl S. Marsh, Systems & Networks Administrator,
AMBIX Systems Corp, Rochester, NY (begin quote):

"Environment:
  Solaris 2.3 Patch 101318-45
  C-Kermit 5A(189) (and presumably this applies to 188 and 190 also)
  eeprom setting:
    ttya-rts-dtr-off=false
    ttya-ignore-cd=false
    ttya-mode=19200,8,n,8,-

"To use C-Kermit on a bidirectional port in this environment, do not use
admintool to configure the port.  Use admintool to delete any services running
on the port and then quit admintool and issue the following command:

  pmadm -a -p zsmon -s ttyb -i root -fu -v 1 -m "`ttyadm -b -d /dev/term/b \
  -l conttyH -m ldterm,ttcompat -s /usr/bin/login -S n`"

[NOTE: This was copied from a fax, so please check it carefully]  where:

  -a = Add service
  -p = pmtag (zsmon)
  -s = service tag (ttyb)
  -i = id to be associated with service tag (root)
  -fu = create utmp entry
  -v = version of ttyadm
  -m = port monitor-specific portion of the port monitor administrative file
       entry for the service
  -b = set up port for bidirectional use
  -d = full path name of device
  -l = which ttylabel in the /etc/ttydefs file to use
  -m = a list of pushable STREAMS modules
  -s = pathname of service to be invoked when connection request received
  -S = software carrier detect on or off (n = off)

"This is exactly how I was able to get Kermit to work on a bi-directional
port without crashing the system."  (End quote)

On the Solaris problem, also see SunSolve Bug ID 1150457 ("Using C-Kermit, get
Bad Trap on receiving prompt from remote system").  Another user reported "So,
I have communicated with the Sun tech support person that submitted this bug
report [1150457].  Apparently, this bug was fixed under one of the jumbo
kernel patches.  It would seem that the fix did not live on into 101318-45, as
this is EXACTLY the error that I see when I attempt to use kermit on my
system."

Later (Aug 94)...  C-Kermit dialout successfully tested on a Sun4m with a
heavily patched Solaris 2.3.  The patches most likely to have been relevant:

101318-50: SunOS 5.3: Jumbo patch for kernel (includes libc, lockd)
101720-01: SunOS 5.3: ttymon - prompt not always visible on a modem connection
101815-01: SunOS 5.3: Data fault in put() NULL queue passed from
                      ttycommon_qfull()
101328-01: SunOS 5.3: Automation script to properly setup tty ports prior to
                      PCTS execution

Still later (Nov 94): another user (Bo Kullmar in Sweden) reports that after
using C-Kermit to dial out on a bidirectional port, the port might not answer
subsequent incoming calls, and says "the problem is easy enough to to fix with
the Serial Port Manager; I just delete the service and and install it again
using the graphical interface, which underneath uses commands like sacadm and
pmadm."  Later Bo reports, "I have found that if I run Kermit with the
following script then it works.  This script is for /dev/cua/a, -s a is the
last a in /dev/cua/a

  #! /bin/sh
  kermit
  sleep 2
  surun pmadm -e -p zsmon -s a

(end quote)

(3.8) C-KERMIT AND SUNOS

Sun SPARCstation users should read the section "Setting up Modem Software" in
the Desktop SPARC Sun System & Network Manager's Guide.  If you don't set up
your serial ports correctly, Kermit (and other communications software) won't
work right.

Reportedly, C-Kermit does not work correctly on a Sun SPARCstation in an Open
Windows window with scrolling enabled.  Disable scrolling, or else invoke
Kermit in a terminal emulation window (xterm, crttool, vttool) under SunView
(this might be fixed in later SunOS releases).

On the Sun with Open Windows, an additional symptom has been reported:
outbound SunLink X.25 connections "magically" translate CR typed at the
keyboard into LF before transmission to the remote host.  This doesn't happen
under SunView.

SET CARRIER ON, when used on the SunOS 4.1 version of C-Kermit (compiled in
the BSD universe), causes the program to hang uninterruptibly when SET LINE
is issued for a device that is not asserting carrier.  When Kermit is built
in the Sys V universe on the same computer, there is no problem (it can be
interrupted with Ctrl-C).  This is apparently a limitation of the BSD-style
tty driver.

SunOS 4.1 C-Kermit has been observed to dump core when running a complicated
script program under cron.  The dump invariably occurs in ttoc(), while trying
to output a character to a TCP/IP TELNET connection.  ttoc() contains a
write() call, and when the system or the network is very busy, the write()
call can get stuck for long periods of time.  To break out of deadlocks caused
by stuck write() calls, there is an alarm around the write().  It is possible
that the core dump occurs when this alarm signal is caught.  (This one has
not been observed recently -- possibly fixed in edit 190.)

On Sun computers with SunOS 4.0 or 4.1, SET FLOW RTS/CTS works only if the
carrier signal is present from the communication device at the time when
C-Kermit enters packet mode or CONNECT mode.  If carrier is not sensed (e.g.
when dialing), C-Kermit does not attempt to turn on RTS/CTS flow control.
This is because the SunOS serial device driver does not allow characters to
be output if RTS/CTS is set (CRTSCTS) but carrier (and DSR) are not present.
Workaround (maybe):  SET CARRIER OFF before giving the SET LINE command,
establish the connection, then SET FLOW RTS/CTS

It has also been reported that RTS/CTS flow control under SunOS 4.1 through
4.1.3 works only on INPUT, not on output, and that there is a patch from Sun
to correct this problem: Patch-ID# T100513-04, 20 July 1993 (this patch might
apply only to SunOS 4.1.3).  It might also be necessary to configure the
eeprom parameters of the serial port; e.g. do the following as root at the
shell prompt:

  eeprom  ttya-ignore-cd=false
  eeprom  ttya-rts-dtr-off=true

There have been reports of file transfer failures on Sun-3 systems when using
long packets and/or large window sizes.  One user says that when this happens,
the console issues many copies of this message:

  chaos vmunix: zs1: ring buffer overflow

This means that SunOS is not scheduling Kermit frequently enough to service
interrupts from the zs serial device (Zilog 8350 SCC serial communication
port) before its input silo overflows.  Workaround: use smaller packets
and/or a smaller window size, or use "nice" to increase Kermit's priority.
Use hardware flow control if available, or remove other active processes
before running Kermit.

SunLink X.25 support in C-Kermit 5A(190) has been built and tested
successfully under SunOS 4.1.3b and SunLink X.25 7.00.

(3.9) C-KERMIT AND ULTRIX

There is no hardware flow control in Ultrix.  That's not a Kermit deficiency,
but an Ultrix one.

Reportedly, DEC ULTRIX 4.3 is immune to C-Kermit's disabling of SIGQUIT,
which is the signal that is generated when the user types Ctrl-\, which kills
the current process (i.e. C-Kermit) and dumps core.  Diagnosis and cure
unknown.  Workaround: before starting C-Kermit -- or for that matter, when you
first log in because this applies to all processes, not just Kermit -- give
the following UNIX command:

  stty quit undef

Certain operations driven by RS-232 modem signal do not work on DECstations or
other DEC platforms whose serial interfaces use MMP connectors (DEC version of
RJ45 telephone jack with with offset tab).  These connectors convey only the
DSR and DTR modem signals, but not carrier (CD), RTS, CTS, or RI.  Use SET
CARRIER OFF to enable communication, or "hotwire" DSR to CD.

(3.10) C-KERMIT AND UNIXWARE

Using the UnixWare 1.1 Application Server, one user reports a system panic
when the following script program is executed:

  set line /dev/tty4
  set speed 9600
  output \13
  connect

The panic does not happen if a PAUSE is inserted:

  set line /dev/tty4
  set speed 9600
  pause 1
  output \13
  connect

This is using a Stallion EasyIO card installed as board 0 on IRQ 12 on
a Gateway 386 with the Stallion-supplied driver.  The problem was reported
to Novell and Stallion, resolution pending.  (Reportedly, this problem
is now fixed.)

(3.11) C-KERMIT AND APOLLO SR10

Reportedly, version 5A(190), when built under Apollo SR10 using "make
sr10-bsd", compiles, links, and executes OK, but leaves the terminal unusable
after it exits -- the "cs7" or "cs8" (character size) parameter has become
cs5.  The terminal must be reset from another terminal.  Cause and cure
unknown.  Suggested workaround: Wrap Kermit in a shell script something like:

  kermit @*
  stty sane

(3.12) C-KERMIT AND TANDY XENIX 3.0

Reportedly, if you type lots of Ctrl-C's during execution of the
initialization file, ghost Kermit processes will be created, and will compete
for the keyboard.  They can only be removed via "kill -9" from another
terminal, or by rebooting.  Diagnosis -- something strange happening with
the SIGINT handler while the process is reading the directory (it seems to
occur during the SET PROMPT [\v(dir)] ... sequence).  Cure: unknown.
Workaround: don't interrupt C-Kermit while it is executing its init file on
the Tandy 16/6000.

(3.13) C-KERMIT AND OSF/1 (DIGITAL UNIX)

Reportedly, if a modem is set for &S0 (assert DSR at all times), the system
resets or drops DTR every 30 seconds; reportedly DEC says to set &S1.

Digital UNIX 3.2 evidently wants to believe your terminal is one line longer
than you say it is, e.g. when a "more" or "man" command is given.  This is has
nothing to do with C-Kermit, but tends to annoy those who use Kermit or other
terminal emulators to access Digital UNIX systems.  Workaround: tell UNIX
to "stty rows 23" (or whatever).

(3.14) C-KERMIT AND SGI IRIX

Reportedly on Silicon Graphics (SGI) machines with IRIX 4.0, Kermit cannot be
suspended by typing the suspend ("swtch") character if it was started from
csh, even though other programs can be suspended this way, and even though the
Z and SUSPEND commands still work correctly.  This is evidently because IRIX's
csh does not deliver the SIGTSTP signal to Kermit.  The reason other programs
can be suspended in the same environment is probably that they do not trap
SIGTSTP themselves, so the shell is doing the suspending rather than the
application.

Reportedly some Indys have bad serial port hardware.  IRIX 5.2, for example,
needs patch 151 to work around this; or upgrade to a later release.
Similarly, IRIX 5.2 has several problems with serial i/o, flow control, etc.
Again, patch or upgrade.

For hardware flow control on IRIX, use the ttyf* (modem control AND hardware
flow control) devices and not the ttyd* (direct) or ttym* (modem control but
no hardward flow control) ones, and obtain the proper "hardware handshaking"
cable from SGI, which is incompatible with the ones for the Macintosh and
NeXT even though they look the same.  "man serial" for further info.

(3.15) C-KERMIT AND THE BEBOX

The BeBox isn't a real product yet, and BeOS -- particularly the POSIX pieces
of it -- aren't finished.  As the POSIX bits are fleshed out, a lot of the
Be-specific code can Be removed.  The workarounds in this version are for
DR7, contributed by an anonymous donor, sufficient to:

  - set line /dev/serial2 (and probably the other serial ports)
  - set speed 115200 (and at least some of the lower baud rates)
  - connect
  - set modem type hayes (and likely others, too)
  - dial [phone number]
  - set send packet length 2048 (other lengths for both send and receive)
  - set receive packet length 2048
  - set file type binary (text mode works, too)
  (with remote kermit session in server mode)
  - put bedrop.jpg
  - get bedrop.jpg
  - get bedrop.jpg bedrop.jpg2
  - finish, bye

The following do not work:
  - kermit does not detect modem hangup
  - !/RUN/PUSH [commandline command]
  - running kermit in remote mode
  - using other protocols (x/y/zmodem)
  - TCP networking interface (Be's TCP/IP API has a ways to go, still)

(4) GENERAL UNIX-SPECIFIC HINTS, LIMITATIONS, AND BUGS

In version 6.0, the default C-Kermit prompt includes your current (working)
directory; for example:

  [/usr/olga] C-Kermit>

If that directory is on an NFS-mounted disk, and NFS stops working or the
disk becomes unavailable, C-Kermit will hang waiting for NFS and/or the disk
to come back.  Whether you can interrupt C-Kermit when it is hung this way
depends on the specific OS.  Kermit has called the operating systems's
getcwd() function, and is waiting for it to return.  Some versions of UNIX
(e.g. HP-UX 9.x) allow this function to be interrupted with SIGINT (Ctrl-C),
others (such as HP-UX 8.x) do not.  To avoid this effect, you can always
use SET PROMPT change your prompt to something that does not involve calling
getcwd(), but if NFS is not responding, C-Kermit will still hang any time you
give a command that refers to the current directory.  Also note that in some
cases, the uninterruptibility of NFS-dependent system or library calls is
considered a bug, and sometimes there are patches.  For HP-UX, for example:

  HP-UX 10.20     libc    PHCO_8764
  HP-UX 10.10     libc    PHCO_8763
  HP-UX 9.x       libc    PHCO_7747       S700
  HP-UX 9.x       libc    PHCO_6779       S800

You might have reason to make C-Kermit the login shell for a specific user,
by entering the pathname of Kermit (possibly with command-line switches, such
as -x to put it in server mode) into the shell field of the /etc/passwd file.
This works pretty well.  In some cases, for "ultimate security", you might
want to use a version built with -DNOPUSH (see ckccfg.doc) for this, but even
if you don't, then PUSHing or shelling out from C-Kermit just brings up a
new copy of C-Kermit (but warning: this does not prevent the user from
explicitly running a shell; e.g. "run /bin/sh"; use NOPUSH to prevent this).

C-Kermit will not work as expected on a remote UNIX system, when used through
the "splitvt" or GNU "screen" programs.  In this case, terminal connections to
the remote UNIX system work, but attempts to transfer files fail because the
screen optimization (or at least, line wrapping, control-character absorption)
done by this package interferes with Kermit's packets.

You might try the following -- what we call "doomsday Kermit" settings to
push packets through even the densest and most obstructive connections, such
as "screen" and "splitvt" (and certain kinds of 3270 protocol emulators):
Give these commands to BOTH Kermit programs:

  SET FLOW NONE
  SET CONTROL PREFIX ALL
  SET RECEIVE PACKET-LENGTH 70
  SET RECEIVE START 62
  SET SEND START 62
  SET SEND PAUSE 100
  SET BLOCK B

If it works, it will be slow.

On UNIX workstations equipped with DOS emulators like SoftPC, watch out for
what these emulators do to the serial port drivers.  After using a DOS
emulator, particularly if you use it to run DOS communications software, you
might have to reconfigure the serial ports for use by UNIX.

On AT&T 7300 (3B1) machines, you might have to "stty nl1" before starting
C-Kermit.  Do this if characters are lost during communications operations.

Under the bash shell (versions prior to 1.07 from CWRU), "pushing" to an
inferior shell and then exiting back to Kermit leaves Kermit in the background
such that it must be explicitly fg'd.  This is reportedly fixed in version
1.07 of bash.

Interruption by Ctrl-Z makes UNIX C-Kermit try to suspend itself with
kill(0,SIGSTOP), but only on systems that support job control, as determined
by whether the symbol SIGTSTP is defined (or on POSIX or SVR4 systems, if
syconf(_SC_JOB_CONTROL) or _POSIX_JOB_CONTROL in addition to SIGTSTP).
However, if Kermit is running under a login shell (such as the original Bourne
shell) that does not support job control, the user's session hangs and must be
logged out from another terminal, or hung up on.  There is no way Kermit can
defend itself against this.  If you use a non-job control shell on a computer
that supports job control, give a command like "stty susp undef" to fix it so
the suspend signal is not attached to any particular key, or give the command
SET SUSPEND OFF to C-Kermit, or build C-Kermit with -DNOJC.

Reportedly, the UNIX C-Kermit server, under some conditions, on certain
particular systems, fails to log out its login session upon receipt of a
BYE command.  Before relying on the BYE command working, test it a few times
to make sure it works on your system: there might be system configuration or
security mechanisms to prevent an inferior process (like Kermit) from
killing a superior one (like the login shell).

(5) INITIALIZATION AND COMMAND FILES

C-Kermit's initialization file for UNIX is .kermrc (lowercase, starts with
period) in your home directory, unless Kermit was built with the system-wide
initialization-file option (see ckuins.doc).

C-Kermit identifies your home directory based on the environment variable,
HOME.  Most UNIX systems set this variable automatically when you log in.  If
C-Kermit can't find your initialization file, check your HOME variable:

  echo $HOME      (at the UNIX prompt)

or:

  echo \$(HOME)   (at the C-Kermit prompt)

If HOME is not defined, or is defined incorrectly, add the appropriate
definition to your UNIX .profile or .login file, depending on your shell:

  setenv HOME full-pathname-of-your-home-directory  (C-Shell, .login file)
or:
  HOME=full-pathname-of-your-home-directory         (sh, ksh, .profile file)
  export HOME

NOTE: Various other operations depend on the correct definition of HOME.
These include the "tilde-expansion" feature, which allows you to refer to
your home directory as "~" in filenames used in C-Kermit commands, e.g.

  send ~/.kermrc

as well as the \v(home) variable.

Prior to version 5A(190), C-Kermit would look for its initialization file in
the current directory if it was not found in the home directory.  This feature
was removed from 5A(190) because it was a security risk.  Some people, however,
liked this behavior and had .kermrc files in all their directories that would
set up things appropriately for the files therein.  If you want this behavior,
you can accomplish it in various ways, for example:

 . Create a shell alias, for example:
   alias kd="kermit -Y ./.kermrc"

 . Create a .kermrc file in your home directory, whose contents are:
   take ./.kermrc

The TAKE command does not search your UNIX PATH for command files.  If a
command file is not in the current directory, you must give a full path
specification for it.  This poses a problem for TAKE commands that are
themselves in TAKE files.  See the trick used in CKETEST.INI...

Suppose you need to pass a password from the UNIX command line to a C-Kermit
script program, in such a way that it does not show up in "ps" or "w" listings.
Here is a method (not guaranteed to be 100% secure, but definitely more secure
than the more obvious methods):

  echo mypassword | kermit myscript

The "myscript" file contains all the commands that need to be executed during
the Kermit session, up to and including EXIT, and also includes an ASK or ASKQ
command to read the password from standard input, which has been piped in from
the UNIX 'echo' command, but it must not include a CONNECT command.  Only
"kermit myscript" shows up in the ps listing.

(6) COMMUNICATION SPEED SELECTION

Version-7 based UNIX implementations, including 4.3 BSD and earlier and
UNIX systems based upon BSD, use a 4-bit field to record a serial device's
terminal speed.  This leaves room for 16 speeds, which are normally:

  0, 50, 75, 110, 134.5, 150, 200, 300, 600, 1200, 1800, 2400, 4800, and 9600

The remaining two are usually called EXTA and EXTB, and are defined by the
particular UNIX implementation.  C-Kermit determines which speeds are
available on your system based on whether symbols for them are defined in your
terminal device header files.  EXTA is generally assumed to be 19200 and EXTB
38400, but these assumptions might be wrong, or they might not apply to a
particular device that does not support these speeds.  Presumably, if you try
to set a speed that is not legal on a particular device, the driver will
return an error, but this can not be guaranteed.

On these systems, it is usually not possible to select a speed of 14400 bps
for use with V.32bis modems.  In that case, use 19200 or 38400 bps, configure
your modem to lock its interface speed and to use RTS/CTS flow control, and
tell C-Kermit to SET SPEED RTS/CTS and SET DIAL SPEED-MATCHING OFF.

Some recent versions of UNIX, and/or terminal device drivers that come with
certain third-party add-in high-speed serial communication interfaces, use the
low "baud rates" to stand for higher ones.  For example, SET SPEED 50 gets you
57600 bps; SET SPEED 75 gets you 76800; SET SPEED 110 gets 115200.

SCO ODT 3.0 is an example where a "baud-rate-table patch" can be applied that
can rotate the tty driver baud rate table such that 600=57600 and 1800=115k
baud.   Similarly for Digiboard multiport/portservers, which have a
"fastbaud" setting that does this.

The situation is similar, but different, in System V.  SVID Third Edition
lists the same speeds, 0 through 38400.

For further details, read the section TERMINAL SPEEDS in ckuins.doc.

(7) COMMUNICATIONS AND DIALING

The SET CARRIER command works as advertised only if the underlying operating
system and device drivers support this feature; in particular only if a read()
operation returns immediately with an error code if the carrier signal goes
away.  And, of course, if the devices themselves (e.g. modems)
are configured appropriately and the cables convey the carrier signal, etc.

When UNIX C-Kermit exits, it closes (and must close) the communications
device.  If you were dialed out, this will most likely hang up the connection.
If you want to get out of Kermit and still use Kermit's communication device,
you have several choices:

 1. Shell out from Kermit or suspend Kermit, and refer to the device literally
    (as in "term -blah -blah < /dev/cua > /dev/cua").

 2. Shell out from Kermit and use the device's file descriptor which Kermit
    makes available to you in the \v(ttyfd) variable.

 3. Use C-Kermit's REDIRECT command.  See the CKCKER.UPD file about this.

If you are having trouble dialing:

 1. Make sure the dialout line is configured correctly.  More
    about this below.

 2. Make sure all necessary patches are installed for your operating
    system.

 3. If you can't dial on a "bidirectional" line, then configure it for
    outbound-only (remove the getty) and try again.  (The mechanisms -- if
    any -- for grabbing bidirectional lines for dialout vary wildly
    among UNIX implementations and releases, and C-Kermit -- which runs on
    well over 300 different UNIX variations -- makes no effort to keep up
    with them; the recommended method for coping with this situation is to
    wrap C-Kermit in a shell script that takes the appropriate actions.)

 4. Make sure C-Kermit's SET DIAL and SET MODEM parameters agree with the
    modem you are actually using -- pay particular attention to SET DIAL
    SPEED-MATCHING.

 5. Try SET DIAL HANGUP OFF before the DIAL command.  Also, SET DIAL DISPLAY
    ON to watch what's happening.  See section 8 of ckuins.doc.

 6. Read pages 50-67 of "Using C-Kermit".

 7. As a last resort, don't use the DIAL command at all; SET CARRIER OFF and
    CONNECT to the modem and dial interactively, or write a script program to
    dial the modem.

Make sure your dialout line is correctly configured for dialing out (as
opposed to login).  The method for doing this is different for each kind of
UNIX system.  Consult your system documentation for configuring lines for
dialing out (for example, SUN SparcStation IPC users should read the section
"Setting up Modem Software" in the Desktop SPARC Sun System & Network
Manager's Guide; HP-9000 workstation users should consult the manual
"Configuring HP-UX for Peripherals", etc).

Symptom: DIAL works, but a subsequent CONNECT command does not.  Diagnosis:
the modem is not asserting Carrier Detect (CD) after the connection is made,
or the cable does not convey the CD signal.  Cure: Reconfigure the modem,
replace the cable.  Workaround: SET CARRIER OFF (at least in System-V based
UNIX versions).

C-Kermit tries to use the 8th bit for data when parity is NONE, and this
generally works on real UNIX terminal (tty) devices, but it often does not
work when the UNIX system is accessed over a network via telnet or rlogin
protocols, including (in many cases) through terminal servers.  For example,
an Encore computer with Annex terminal servers only gives a 7-bit path if
the rlogin protocol is selected in the terminal server but it gives the full
8 bits if the proprietary RDP protocol is used.

If file transfer does not work through a host to which you have rlogin'd,
use "rlogin -8" rather than "rlogin".  If that doesn't work, tell both Kermit
programs to "set parity space".

The Encore TELNET server does not allow long bursts of input.  When you have
a TELNET connection to an Encore, tell C-Kermit on the Encore to SET RECEIVE
PACKET-LENGTH 200 or thereabouts.

For Berkeley-UNIX-based systems (4.3BSD and earlier), Kermit includes code to
use LPASS8 mode when parity is none, which is supposed to allow 8-bit data and
Xon/Xoff flow control at the same time.  However, as of edit 174, this code is
entirely disabled because it is unreliable: even though the host operating
system might (or might not) support LPASS8 mode correctly, the host access
protocols (terminal servers, telnet, rlogin, etc) generally have no way of
finding out about it and therefore render it ineffective, causing file
transfer failures.  So as of edit 174, Kermit once again uses rawmode for
8-bit data, and so there is no Xon/Xoff flow control during file transfer or
terminal emulation in the Berkeley-based versions (4.3 and earlier, not 4.4).

Also on Berkeley-based systems (4.3 and earlier), there is apparently no way
to configure a dialout line for proper carrier handling, i.e. ignore carrier
during dialing, require carrier thereafter, get a fatal error on any attempt
to read from the device after carrier drops (this is handled nicely in System
V by manipulation of the CLOCAL flag).  The symptom is that carrier loss does
not make C-Kermit pop back to the prompt automatically.  This is evident on
the NeXT, for example, but not on SunOS, which supports the CLOCAL flag.  This
is not a Kermit problem, but a limitation of the underlying operating system.
For example, the cu program on the NeXT doesn't notice carrier loss either,
whereas cu on the Sun does.

On certain AT&T UNIX systems equipped with AT&T modems, DIAL and HANGUP don't
work right.  Workarounds: (1) SET DIAL HANGUP OFF before attempting to dial;
(2) If HANGUP doesn't work, SET LINE, and then SET LINE <device> to totally
close and reopen the device.  If all else fails, SET CARRIER OFF.

C-Kermit does not contain any particular support for AT&T DataKit devices.
You can use Kermit software to dial in to a DataKit line, but C-Kermit does
not contain the specialized code required to dial out from a DataKit line.  If
the UNIX system is connected to DataKit via serial ports, dialout should work
normally (e.g. set line /dev/ttym1, set speed 19200, connect, and then see the
DESTINATION: prompt, from which you can connect to another computer on the
DataKit network or to an outgoing modem pool, etc).  But if the UNIX system
is connected to the DataKit network through the special DataKit interface
board, then SET LINE to a DataKit pseudodevice (such as /dev/dk031t) will not
work (you must use the DataKit "dk" or "dkcu" program instead).

In some BSD-based UNIX C-Kermit versions, SET LINE to a port that has nothing
plugged in to it with SET CARRIER ON will hang the program (as it should), but
it can't be interrupted with Ctrl-C.  The interrupt trap is correctly armed,
but apparently the UNIX open() call cannot be interrupted in this case.  When
SET CARRIER is OFF or AUTO, the SET LINE will eventually return, but then the
program hangs (uninterruptibly) when the EXIT or QUIT command (or, presumably,
another SET LINE command) is given.  The latter is probably because of the
attempt to hang up the modem.  (In edit 169, a timeout alarm was placed around
this operation.)

With SET DIAL HANGUP OFF in effect, the DIAL command might work only once,
but not again on the same device.  In that case, give a SET LINE command
with no arguments to close the device, and then another SET LINE command for
the desired device.  Or rebuild your version of Kermit with the -DCLSOPN
compile-time switch (see ckuins.doc).

The DIAL command says "To cancel: Type your interrupt character (normally
Ctrl-C)."  This is just one example of where program messages and
documentation assume your interrupt character is Ctrl-C.  But it might be
something else.  In most (but not necessarily all) cases, the character
referred to is the one that generates the SIGINT signal.  If Ctrl-C doesn't
act as an interrupt character for you, type the Unix command "stty -a" or
"stty all" or "stty everything" to see what your interrupt character is.
(Kermit could be made to find out what the interrupt character is, but this
would require a lot of system-dependent coding and #ifdefs, and a new routine
and interface between the system-dependent and system-independent parts of the
program.)

In general, the hangup operation on a serial communication device is prone
to failure.  C-Kermit tries to support many, many different kinds of
computers, and there seems to be no portable method for hanging up a modem
connection (i.e. turning off the RS-232 DTR signal and then turning it back on
again).  If HANGUP, DIAL, and/or Ctrl-\H do not work for you, and you are a
programmer, look at the tthang() function in ckutio.c and see if you can add
code to make it work correctly for your system, and send the code to the
address above.  (NOTE: This problem has been largely sidestepped as of edit
188, in which Kermit first attempts to hang up the modem by "escaping back"
via +++ and then giving the modem's hangup command, e.g. ATH0, when DIAL
MODEM-HANGUP is ON, which is the default setting.)

Even when Kermit's modem-control software is configured correctly for your
computer, it can only work right if your modem is also configured to assert
the CD signal when it is connected to the remote modem and to hang up the
connection when your computer drops the DTR signal.  So before deciding Kermit
doesn't work with your modem, check your modem configuration AND the cable (if
any) connecting your modem to the computer -- it should be a straight-through
modem cable conducting the signals FG, SG, TD, RD, RTS, CTS, DSR, DTR, CD,
and RI.

Many UNIX systems keep aliases for dialout devices; for example, /dev/acu
might be an alias for /dev/tty00.  But most of these UNIX systems also use
UUCP lockfile conventions that do not take this aliasing into account, so if
one user assigns (e.g.) /dev/acu, then another user can still assign the same
device by referring to its other name.  This is not a Kermit problem --
Kermit must follow the lockfile conventions used by the vendor-supplied
software (cu, tip, uucp).

The SET FLOW-CONTROL KEEP option should be given *before* any communication
(dialing, terminal emulation, file transfer, INPUT/OUTPUT/TRANSMIT, etc) is
attempted, if you want C-Kermit to use all of the device's preexisting
flow-control related settings.  The default flow-control setting is XON/XOFF,
and it will take effect when the first communication-related command is given,
and a subsequent SET FLOW KEEP command will not necessarily know how to
restore *all* of the device's original flow-control settings.

(8) HARDWARE FLOW CONTROL

SET FLOW RTS/CTS is available in UNIX C-Kermit only when the underlying
operating system provides an Application Program Interface (API) for turning
this feature on and off under program control, which turns out to be a rather
rare feature among UNIX systems.  To see if your UNIX C-Kermit version
supports hardware flow control, type "set flow ?" at the C-Kermit prompt, and
look for "rts/cts" among the options.  Other common situations include:

 1. The API is available, so "set flow rts/cts" appears as a valid C-Kermit
    command, but it doesn't do anything because the device driver (part of
    the operating system) was never coded to do hardware flow control.  This
    is common among System V R4 implementations (details below).

 2. The API is not available, so "set flow rts/cts" does NOT appear as a valid
    C-Kermit command, but you can still get RTS/CTS flow control by selecting
    a specially named device in your SET LINE command.  Examples:

      NeXTSTEP: /dev/cufa instead of /dev/cua, /dev/cufb instead of /dev/cub
      (68040 only; "man zs" for further info).

      IRIX: /dev/ttyf2 instead of /dev/ttyd2 or /dev/ttym2 ("man 7 serial").

 3. The API is available, doesn't work, but a workaround as in (2) can be used.

 4. The API is available, but Kermit doesn't know about it.  In these cases,
    you can usually use an stty command to enable RTS/CTS on the device, e.g.
    "stty crtscts" or "stty ctsflow", "stty rtsflow", before starting Kermit,
    and then tell Kermit to SET FLOW KEEP.

 5. No API and no special device drivers.  Hardware flow control is completely
    unavailable.

System V R4 based UNIXes are supposed to supply a <termiox.h> file, which
gives Kermit the necessary interface to command the terminal driver to
enable/disable hardware flow control.  Unfortunately, but predictably, many
implementations of SVR4 whimsically place this file in /usr/include/sys rather
than /usr/include (where SVID clearly specifies it should be; see SVID, Third
Edition, V1, termiox(BA_DEV).  Thus if you build C-Kermit with any of the
makefile entries that contain -DTERMIOX or -DSTERMIOX (the latter to select
<sys/termiox.h>), C-Kermit will have "set flow rts/cts" and possibly other
hardware flow-control related commands.  BUT...  That does not necessarily
mean that they will work.  In some cases, the underlying functions are simply
not coded into the operating system.

(9) TERMINAL CONNECTION AND KEY MAPPING

UNIX C-Kermit's SET KEY command currently can not be used with keys that
generate "wide" scan codes or multibyte sequences, such as workstation
function or arrow keys, because UNIX C-Kermit does not have direct access to
the keyboard.  More about this in CKCKER.BWR.

However, many UNIX workstations and/or console drivers provide their own key
mapping feature.  With xterm, for example, you can use 'xmodmap' ("man
xmodmap" for details); here is an xterm mapping to map the Sun keyboard to DEC
VT200 values for use with VT-terminal oriented applications like VMS EVE:

  keycode 101=KP_0
  keycode 119=KP_1
  keycode 120=KP_2
  keycode 121=KP_3
  keycode 98=KP_4
  keycode 99=KP_5
  keycode 100=KP_6
  keycode 75=KP_7
  keycode 76=KP_8
  keycode 77=KP_9
  keycode 52=KP_F1
  keycode 53=KP_F2
  keycode 54=KP_F3
  keycode 57=KP_Decimal
  keycode 28=Left
  keycode 29=Right
  keycode 30=KP_Separator
  keycode 105=KP_F4
  keycode 78=KP_Subtract
  keycode 8=Left
  keycode 10=Right
  keycode 32=Up
  keycode 33=Down
  keycode 97=KP_Enter

Users of Linux consoles can use loadkeys ("man dumpkeys loadkeys keytables"
for details.  The format used by loadkeys is compatible with that used by
Xmodmap, although it is not definitely certain that the keycodes are
compatible for different keyboard types (e.g. Sun vs HP vs PC, etc).

UNIX GNU EMACS includes a "kermit" library that allows Kermit connections to
be made to other computers from within an EMACS window.  As of June 1994,
there is also a Kermit file transfer library for GNU EMACS.

(10) FILE TRANSFER

UNIX C-Kermit does not reject incoming files on the basis of size.  There
appears to be no good (reliable, portable) way to determine in advance how
much disk space is available, either on the device, or (when quotas are
involved) to the user.

File transfer will fail if the incoming file is bigger than your ULIMIT.
Use the UNIX ulimit command to examine or change your ULIMIT (the number is
in 512-byte blocks, i.e. 0.5K).

UNIX C-Kermit discards all carriage returns from incoming files when in text
mode.

If C-Kermit is receiving a file on a dialup connection and the connection
hangs up, the SIGHUP signal is delivered to the top-level shell, which kills
all processes (including Kermit and any of its subforks) and closes all open
files, including the file that was being received.  Even if you have told
Kermit to SET FILE INCOMPLETE DISCARD, the partially received file is kept.
See comments in ckutio.c (search for SIGHUP) for details.

If you SET FILE DISPLAY FULLSCREEN, and C-Kermit complains "Sorry, terminal
type not supported", it means that the terminal library (termcap or termlib)
that C-Kermit was built with does not know about a terminal whose name is the
current value of your TERM environment variable.  If this happens, EXIT from
C-Kermit and set a UNIX terminal type from among the supported values that is
also supported by your terminal emulator, or else have an entry for your
terminal type added to the system termcap and/or terminfo database.

If you attempt to suspend C-Kermit during local-mode file transfer and then
continue it in the background (via bg), it will block for "tty output" if
you are using the FULLSCREEN file transfer display.  This is apparently
a problem with curses.  Moving a local-mode file transfer back and forth
between foreground and background works correctly, however, with the SERIAL,
CRT, or NONE file transfer displays.

If C-Kermit's command parser no longer echoes, or otherwise acts strangely,
after returning from a file transfer with the fullscreen (curses) display,
and your version of UNIX is based on AT&T System V, then try rebuilding your
version of C-Kermit with -DCK_NEWTERM.  Similarly if it echoes doubly, which
might even happen during a subsequent CONNECT session.  If rebuilding with
-DCK_NEWTERM doesn't fix it, then there is something very strange about your
systems curses library, and you should probably not use it.  Tell C-Kermit
to SET FILE DISPLAY CRT or anything else other than FULLSCREEN, or rebuild
without -DCK_CURSES, and without linking with (termlib and) curses.

It has been observed on a couple platforms -- e.g. BSDI and QNX -- that the
curses display works properly only once.  The second and subsequent times,
the display is a mess.  The reason is unknown, the cure is unknown.  See the
comments in screenc() in ckuusx.c.  In one other case (one of the Linux
distributions), a cure was obtained by linking to a different curses library
(ncurses rather than curses).

Reportedly, when using "MSEND *" from a 14-character filename UNIX system to
another system (e.g. BSD) that allows longer names, with SET FILE NAMES
LITERAL, any files with 14-character names will have a space added to the end
of the name on the receiving machine (this *should* be fixed in 6.0).

Optimum file transfer performance is a matter of tuning parameters like packet
length, window size, control-character unprefixing, and on serial connections,
ensuring there is an effective flow control method, preferably hardware (such
as RTS/CTS).

However, a fully-configured C-Kermit program can be slower than a minimally
configured one simply because of its size.  A command-line-only version that
is stripped of every conceivable feature not affecting file transfer (such as
"sunos41m" for the Sun or "dellsys5r4m" for Dell) can move files faster than a
full-featured one.  Thus, it might make sense to keep a minimal version
available as well as a full-featured one.  See the files ckuins.doc and
ckccfg.doc as well as the makefile for how to do this.

A fairly substantial reduction in size and a noticeable improvement in speed
can be obtained simply by rebuilding C-Kermit without the debugging feature:

  make <entryname> KFLAGS=-DNODEBUG

See ckccfg.doc for more detailed information about configuration.

(11) EXTERNAL FILE TRANSFER PROTOCOLS

UNIX C-Kermit can be used in conjunction with other communications software
in various ways.  C-Kermit can be invoked from another communications program
as an "external protocol", and C-Kermit can also invoke other communication
software to perform external protocols.

This sort of operation makes sense only when you are dialing out from your
UNIX system.  If the UNIX system is the one you have dialed in to, you don't
need any of these tricks.  Just run the desired software on your UNIX system
instead of Kermit.  When dialing out from a UNIX system, the difficulty is
getting two programs to share the same communication device in spite of the
UNIX UUCP lockfile mechanism, which would normally prevent any sharing, and
preventing the external protocol from closing (and therefore hanging up) the
device when it exits back to the program that invoked it.
(This section deleted; see ckcker.upd.)

"pcomm" is a general-purpose terminal program that provides file transfer
capabilities itself (X- and YMODEM variations) and the ability to call on
external programs to do file transfers (ZMODEM and Kermit, for example).  You
can tell pcomm the command to send or receive a file with an external
protocol:
            send                receive
    ZMODEM        sz <filename>            rz
    Kermit        kermit -s <filename>        kermit -r

pcomm runs external programs for file transfer by making stdin and stdout
point to the modem port, and then exec-ing "/bin/sh -c xxx" (where xxx is the
appropriate command).  However, C-Kermit does not treat stdin and stdout as
the communication device unless you instruct it:

            send                receive
    Kermit        kermit -l 0 -s <filename>    kermit -l 0 -r

The "-l 0" option means to use file descriptor 0 for the communication device.

In general, any program can pass any open file descriptor to C-Kermit for the
communication device in the "-l" command-line option.  When Kermit is given
a number as the argument to the "-l" option, it simply uses it as a file
descriptor, and it does not attempt to close it upon exit.

Here's another example, for Seyon (a Linux communication program).  First try
the technique above.  If that works, fine; otherwise...  If Seyon does not
give you a way to access and pass along the file descriptor, but it starts up
the Kermit program with its standard i/o redirected to its (Seyon's)
communications file descriptor, you can also experiment with the following
method, which worked here in brief tests on SunOS.  Instead of having Seyon
use "kermit -r" or "kermit -s filename" as its Kermit protocol commands, use
something like this (examples assume C-Kermit 6.0):

  For serial connections:

    kermit -YqQl 0 -r                     <-- to receive
    kermit -YqQl 0 -s filename(s)         <-- to send one or more files

  For Telnet connections:

    kermit -YqQF 0 -r                     <-- to receive
    kermit -YqQF 0 -s filename(s)         <-- to send one or more files

Command line options:

  Y    - skip executing the init file
  Q    - use fast file transfer settings
  l 0  - transfer files using file descriptor 0 for a serial connection
  F 0  - transfer files using file descriptor 0 for a Telnet connection
  q    - quiet - no messages
  r    - receive
  s    - send

(11.2) INVOKING EXTERNAL PROTOCOLS FROM C-KERMIT

   (This section is obsolete, but not totally useless.
    See section 8 of CKCKER.UPD.)

After you have opened a communication link with C-Kermit's SET LINE (SET PORT)
or SET HOST (TELNET) command, C-Kermit makes its file descriptor available to
you in the \v(ttyfd) variable so you can make it available to other programs
that you RUN from C-Kermit.  Here, for example, C-Kermit runs itself as an
external protocol:

  C-Kermit>set modem type hayes
  C-Kermit>set line /dev/acu
  C-Kermit>set speed 2400
  C-Kermit>dial 7654321
   Call complete.
  C-Kermit>echo \v(ttyfd)
   3
  C-Kermit>run kermit -l \v(ttyfd)

Other programs that accept open file descriptors on the command line can be
started in the same way.

You can also use your shell's i/o redirection facilities to assign C-Kermit's
open file descriptor (ttyfd) to stdin or stdout.  For example, old versions of
the UNIX ZMODEM programs, sz and rz, when invoked as external protocols,
expect to find the communication device assigned to stdin and stdout with no
option for specifying any other file descriptor on the sz or rz command line.
However, you can still invoke sz and rz as exterior protocols from C-Kermit if
your current shell ($SHELL variable) is ksh (the Korn shell) or bash (the
Bourne-Again shell), which allows assignment of arbitrary file descriptors to
stdin and stdout:

  C-Kermit> run rz <&\v(ttyfd) >&\v(ttyfd)

or:

  C-Kermit> run sz oofa.zip <&\v(ttyfd) >&\v(ttyfd)

In version 5A(190) and later, you can use C-Kermit's REDIRECT command, if it
is available in your version of C-Kermit, to accomplish the same thing without
going through the shell:

  C-Kermit> redirect rz

or:

  C-Kermit> redirect sz oofa.zip

A complete set of rz,sz,rb,sb,rx,sx macros for UNIX C-Kermit is defined in
the file ckurzsz.ini.  It automatically chooses the best redirection method.

(11.3) USING C-KERMIT WITH TERM

The "term" program provides an error-corrected, multiplexed connection
between two UNIX systems, allowing you to run multiple applications over a
single connection, for example several terminal windows and a file transfer
simultaneously.  Term depends on a communications application (such as
C-Kermit) to make the connection and then redirect it to term's standard i/o.
The advantages of using C-Kermit rather than other communication programs for
this include:

 . C-Kermit's script language lets you automate the entire process.

 . With C-Kermit's REDIRECT command, term sessions are not limited to serial
   connections, but can work over network connections (TCP/IP, X.25) too.

Here is an example showing how to set up a term session between two UNIX
systems with with C-Kermit (assuming the connection has already been made
by C-Kermit, e.g. by dialing up):

  C-Kermit> connect
  login: xxx
  Password: xxx
  $ exec term -r -s 38400 -A
  ^\c (escape back)
  C-Kermit>redirect term -s 38400 -A &
  C-Kermit>push
  $

Now you can run term clients such as trsh and tupload at the local shell
prompt.

(12) MISCELLANEOUS

If C-Kermit has problems creating files in writable directories when it is
installed setuid or setgid on BSD-based versions of UNIX such
as NeXTSTEP 3.0, it probably needs to be rebuilt with the -DSW_ACC_ID
comilation switch (see ckuins.doc).

Reportedly, when coming into a Sequent UNIX (DYNIX) system through an X.25
connection, Kermit doesn't work right because the Sequent's FIONREAD ioctl
returns incorrect data.  To work around, use the 1-character-at-a-time version
of myread() in ckutio.c (i.e. undefine MYREAD in ckutio.c and rebuild the
program).

------------------------------

USER REPORTS -

Date: Thu, 12 Mar 92 1:59:25 MEZ
From: Walter Mecky <[e-mail]>
Subject: Help.Unix.sw
To: [e-mail], [e-mail]

PRODUCT:    Unix
RELEASE:    Dell SVR4 V2.1 (is USL V3.0)
MACHINE:    AT-386
PATHNAME:    /usr/lib/libc.so.1
        /usr/ccs/lib/libc.a
ABSTRACT:    Function ttyname() does not close its file descriptor
DESCRIPTION:
    ttyname(3C) opens /dev but never closes it. So if it is called
    often enough the open(2) in ttyname() fails. Because the broken
    ttyname() is in the shared lib too all programs using it can
    fail if they call it often enough. One important program is
    uucico which calls ttyname for every file it transfers.

Here is a little test program if your system has the bug:

#include <stdlib.h>
#include <stdio.h>
main() {
    int i = 0;
    while (ttyname(0) != NULL)
      i++;
    perror("ttyname");
    printf("i=%d\n", i);
}

If this program runs longer than some seconds you don't have the bug.

WORKAROUND:
    None
FIX:
    Very easy if you have source code.

Another user reports some more explicit symptoms and recoveries:

> What happens is when invoking ckermit we get one of the following
> error messages:
>   You must set line
>   Not a tty
>   No more processes.
> One of the following three actions clears the peoblem:
>   shutdown -y -g0 -i6
>   kill -9 the ttymon with the highest PID
>   Invoke sysadm and disable then enable the line you want to use.
> Turning off respawn of sac -t 300 and going to getty's and uugetty's
> does not help.
>
> Also C-Kermit reports "?timed out closing /dev/ttyxx".
> If this happens all is well.

------------------------------

(Note: the following problem also occurs on SGI and probably many other
UNIX systems):

From: James Spath <[e-mail]>
To: [e-mail]
Date: Wed, 9 Sep 1992 20:20:28 -0400
Subject: C-Kermit vs uugetty (or init) on Sperry 5000

We have sucessfully compiled the above release on a Unisys/Sperry 5000/95.  We
used the sys5r3 option, rather than sys5r2 since we have VR3 running on our
system.  In order to allow dialout access to non-superusers, we had to do
"chmod 666 /dev/tty###", where it had been -rw--w--w- (owned by uucp), and to
do "chmod +w /usr/spool/locks".  We have done text and binary file transfers
through local and remote connections.

The problem concerning uucp ownership and permissions is worse than I thought
at first.  Apparently init or uugetty changes the file permissions after each
session.  So I wrote the following C program to open a set of requested tty
lines.  I run this for any required outgoing line prior to a Kermit session.

   ------ cut here -------
/* opentty.c -- force allow read on tty lines for modem i/o */
/* idea from: restrict.c -- Systsem 5 Admin book Thomas/Farrow p. 605 */
/* /jes jim spath {[e-mail] } */
/* 08-Sep-92 NO COPYRIGHT. */
/* this must be suid to open other tty lines */

/* #define DEBUG */
#define TTY "/dev/tty"
#define LOK "/usr/spool/locks/LCK..tty"
#include <stdio.h>

/* allowable lines: */
#define TOTAL_LINES 3
static char allowable[TOTAL_LINES][4] = { "200", "201", "300" };
static int total=TOTAL_LINES;
int allow;

/* states: */
#define TTY_UNDEF 0
#define TTY_LOCK  1
#define TTY_OKAY  2

main(argc, argv)
int argc; char *argv[]; {
    char device[512];
    char lockdev[512];
    int i;
    if (argc == 1) {
    fprintf(stderr, "usage: open 200 [...]\n");
    }
    while (--argc > 0 && (*++argv) != NULL ) {
#ifdef DEBUG
    fprintf(stderr, "TRYING: %s%s\n", TTY, *argv);
#endif
    sprintf(device, "%s%s", TTY, *argv);
    sprintf(lockdev, "%s%s", LOK, *argv);
    allow = TTY_UNDEF; i = 0;
    while (i <= total) { /* look at all defined lines */
#ifdef DEBUG
        fprintf(stderr, "LOCKFILE? %s?\n", lockdev);
#endif
        if (access(lockdev, 00) == 0) {
        allow=TTY_LOCK;
        break;
        }
#ifdef DEBUG
        fprintf(stderr, "DOES:%s==%s?\n", allowable[i], *argv);
#endif
        if (strcmp(allowable[i], *argv) == 0)
          allow=TTY_OKAY;
        i++;
    }
#ifdef DEBUG
    fprintf(stderr, "allow=%d\n", allow);
#endif
    switch (allow) {
      case TTY_UNDEF:
        fprintf (stderr, "open: not allowed on %s\n", *argv);
        break;
      case TTY_LOCK:
        fprintf (stderr, "open: device locked: %s\n", lockdev);
        break;
      case TTY_OKAY:
        /* attempt to change mode on device */
        if (chmod (device, 00666) < 0)
          fprintf (stderr, "open: cannot chmod on %s\n", device);
        break;
      default:
        fprintf (stderr, "open: FAULT\n");
    }
    }
    exit (0);
}

------------------------------

(End of CKUKER.BWR)