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8 As of: C-Kermit 9.0.300, 30 June 2011
9 This page last updated: Tue Jun 28 08:54:30 2011 (New York USA Time)
11 IF YOU ARE READING A PLAIN-TEXT version of this document, it is a
12 plain-text dump of a Web page. You can visit the original (and
13 possibly more up-to-date) Web page here:
15 [11]http://www.columbia.edu/kermit/ckcbwr.html
17 This document contains platform-independent C-Kermit hints and tips.
18 Also see the platform-specific C-Kermit hints and tips document for
19 your platform, for example:
21 [12]http://www.columbia.edu/kermit/ckubwr.html
23 for Unix. This document also applies to [13]Kermit 95 for Windows,
24 which is based on C-Kermit.
26 [ [14]C-Kermit ] [ [15]TUTORIAL ]
31 1. [17]INCOMPATIBLE CHANGES
32 2. [18]THE C-KERMIT COMMAND PARSER
33 3. [19]MULTIPLE SESSIONS
34 4. [20]NETWORK CONNECTIONS
35 5. [21]MODEMS AND DIALING
36 6. [22]DIALING HINTS AND TIPS
37 7. [23]TERMINAL SERVERS
38 8. [24]TERMINAL EMULATION
41 11. [27]SCRIPT PROGRAMMING
45 [ [28]Top ] [ [29]Contents ] [ [30]Next ]
47 Source-level patches for C-Kermit 8.0.211:
51 1. INCOMPATIBLE CHANGES
53 [ [31]Top ] [ [32]Contents ] [ [33]Next ]
55 These are not necessarily exhaustive lists.
59 C-Kermit 6.0 was released 6 September 1996 and is completely documented
60 in [34]Using C-Kermit, 2nd Edition. The following incompatible changes
61 were made in C-Kermit 6.0:
63 * Unless you tell C-Kermit otherwise, if a serial or network
64 connection seems to be open, and you attempt to EXIT or to open a
65 new connection, C-Kermit warns you that an active connection
66 appears to be open and asks you if you really want to close it. If
67 you do not want these warnings, add SET EXIT WARNING OFF to your
68 customization file or script, or give this command at the prompt.
69 * The default for SET { SEND, RECEIVE } PATHNAMES was changed from ON
70 to OFF, to prevent unexpected creation of directories and
71 depositing of incoming files in places you might not know to look.
72 * The default for SET FILE INCOMPLETE was changed from DISCARD to
73 KEEP to allow for file transfer recovery.
74 * The default file-transfer block-check is now 3, rather than 1. If
75 the other Kermit does not support this, the two will drop back to
76 type 1 automatically unless the other Kermit fails to follow the
77 protocol specification.
78 * The default flow-control is now "auto" ("do the right thing for
79 each type of connection"), not Xon/Xoff.
80 * Backslash (\) is no longer a command continuation character. Only -
81 (hyphen, dash) may be used for this in C-Kermit 6.0 and later.
82 * Negative INPUT timeout now results in infinite wait, rather than 1
87 C-Kermit 7.0 was released 1 January 2000. Its new features are
88 documented in the C-Kermit 7.0 Supplement,
89 [35]http://www.columbia.edu/kermit/ckermit2.html. The following
90 incompatible changes were made in C-Kermit 7.0:
91 * The "multiline GET" command is gone. Now use either of the
92 following forms instead:
93 get remote-name local-name
94 get /as-name:local-name remote-name
96 If either name contains spaces, enclose it in braces (or, in
97 C-Kermit 8.0, doublequotes).
98 * To include multiple file specifications in a GET command, you must
99 now use MGET rather than GET:
100 mget file1 file2 file3 ...
102 * C-Kermit 7.0 and later use FAST Kermit protocol settings by
103 default. This includes "unprefixing" of certain control characters.
104 Because of this, file transfers that worked with previous releases
105 might not work in the new release especially against a
106 non-Kermit-Project Kermit protocol implementation (but it is more
107 likely that they will work, and much faster). If a transfer fails,
108 you'll get a context-sensitive hint suggesting possible causes and
109 cures. Usually SET PREFIXING ALL does the trick.
110 * By default C-Kermit 7.0 and later send files in text or binary mode
111 by looking at each file to see which is the appropriate mode. To
112 restore the previous behavior, put SET TRANSFER MODE MANUAL and the
113 desired SET FILE TYPE (TEXT or BINARY) in your C-Kermit
115 * The RESEND and REGET commands automatically switch to binary mode;
116 previously if RESEND or REGET were attempted when FILE TYPE was
117 TEXT, these commands would fail immediately, with a message telling
118 you they work only when the FILE TYPE is BINARY. Now they simply do
120 * SET PREFIXING CAUTIOUS and MINIMAL now both prefix linefeed (10 and
121 138) in case rlogin, ssh, or cu are "in the middle", since
122 otherwise <LF>~ might appear in Kermit packets, and this would
123 cause rlogin, ssh, or cu to disconnect, suspend,escape back, or
124 otherwise wreck the file transfer. Xon and Xoff are now always
125 prefixed too, even when Xon/Xoff flow control is not in effect,
126 since unprefixing them has proven dangerous on TCP/IP connections.
127 * In UNIX, VMS, Windows, and OS/2, the DIRECTORY command is built
128 into C-Kermit itself rather than implemented by running an external
129 command or program. The built-in command might not behave the way
130 the platform-specific external one did, but many options are
131 available for customization. Of course the underlying
132 platform-specific command can still be accessed with "!", "@", or
133 "RUN" wherever the installation does not forbid. In UNIX, the "ls"
134 command can be accessed directly as "ls" in C-Kermit.
135 * SEND ? prints a list of switches rather than a list of filenames.
136 If you want to see a list of filenames, use a (system-dependent)
137 construction such as SEND ./? (for UNIX, Windows, or OS/2), SEND
139 * In UNIX, OS-9, and Kermit 95, the wildcard characters in previous
140 versions were * and ?. In C-Kermit 7.0 they are *, ?, [, ], {, and
141 }, with dash used inside []'s to denote ranges and comma used
142 inside {} to separate list elements. If you need to include any of
143 these characters literally in a filename, precede each one with
145 * SET QUIET { ON, OFF } is now on the command stack, just like SET
146 INPUT CASE, SET COUNT, SET MACRO ERROR, etc, as described on p.458
147 of [36]Using C-Kermit, 2nd Edition. This allows any macro or
148 command file to SET QUIET ON or OFF without worrying about saving
149 and restoring the global QUIET value. For example, this lets you
150 write a script that tries SET LINE on lots of devices until it
151 finds one free without spewing out loads of error messages, and
152 also without disturbing the global QUIET setting, whatever it was.
153 * Because of the new "." operator (which introduces assignments),
154 macros whose names begin with "." can not be invoked "by name".
155 However, they still can be invoked with DO or \fexecute().
156 * The syntax of the EVALUATE command has changed. To restore the
157 previous syntax, use SET EVALUATE OLD.
158 * The \v(directory) variable now includes the trailing directory
159 separator; in previous releases it did not. This is to allow
160 constructions such as:
163 to work across platforms that might have different directory
164 notation, such as UNIX, Windows, and VMS.
165 * Prior to C-Kermit 7.0, the FLOW-CONTROL setting was global and
166 sticky. In C-Kermit 7.0, there is an array of default flow-control
167 values for each kind of connection, that are applied automatically
168 at SET LINE/PORT/HOST time. Thus a SET FLOW command given before
169 SET LINE/PORT/HOST is likely to be undone. Therefore SET FLOW can
170 be guaranteed to have the desired effect only if given after the
171 SET LINE/PORT/HOST command.
172 * Character-set translation works differently in the TRANSMIT command
173 when (a) the file character-set is not the same as the local end of
174 the terminal character-set, or (b) when the terminal character-set
179 The following incompatible changes were made in C-Kermit 8.0:
180 * C-Kermit now accepts doublequotes in most contexts where you
181 previously had to use braces to group multiple words into a single
182 field, or to force inclusion of leading or trailing blanks. This
183 might cause problems in contexts where you wanted the doublequote
184 characters to be taken literally. Consult [37]Section 5 of the
185 [38]C-Kermit 8.0 Update Notes for further information.
186 * Using the SET HOST command to make HTTP connections is no longer
187 supported. Instead, use the new [39]HTTP OPEN command.
191 The [40]\fsplit() function is incredibly handy, it can do almost
192 anything, up to and including parsing a LISP program (the underlying
193 code is the basis of the [41]S-Expression interpreter). But did you
194 ever try to use it to parse (say) a Tab-Separated-List (TSV file) or
195 Comma-Separated-List (CSV)? It works as expected as long as the data
196 contains only 7-bit characters. But if your data contains (say) Spanish
197 or German or Russian text written in an 8-bit character set such as ISO
198 8859-1, every 8-bit character (any value 128-255) is treated as a break
199 character. This is fixed in C-Kermit 9.0 by treating all 8-bit bytes as
200 "include" characters rather than break characters, a total reversal of
201 past behavior. I don't think it will affect anyone though, because if
202 this had happened to anyone, I would have heard about it!
204 Since most standard 8-bit character sets have control characters in
205 positions 128-160, it might have made sense to keep 128-160 in the
206 break set, but with the proliferation of Microsoft Windows code pages,
207 there is no telling which 8-bit character is likely to be some kind of
208 text, e.g. "smart quotes" or East European or Turkish accented letters.
210 2. THE C-KERMIT COMMAND PARSER
212 [ [42]Top ] [ [43]Contents ] [ [44]Next ] [ [45]Previous ]
214 Various command-related limits are shown in the following table, in
215 which the sample values are for a "large memory model" build of
216 C-Kermit, typical for modern platforms (Linux, Solaris, AIX, VMS, etc).
217 You can see the values for your version of Kermit by giving the SHOW
218 FEATURES command. The maximum length for a Kermit command (CMDBL) also
219 determines the maximum length for a macro definition, since DEFINE is
220 itself a command. The maximum length for a variable name is between 256
221 and 4096 characters, depending on the platform; for array declarations
222 and references, that includes the subscript.
226 Number of characters in a command CMDBL 32763 ckucmd.h
227 Number of chars in a field of a command ATMBL 10238 ckucmd.h
228 Nesting level for command files MAXTAKE 54 ckuusr.h
229 Nesting level for macros MACLEVEL 128 ckuusr.h
230 Nesting level for FOR / WHILE loops FORDEPTH 32 ckuusr.h
231 Number of macros MAC_MAX 16384 ckuusr.h
232 Size of INPUT buffer INPBUFSIZ 4096 ckuusr.h
233 Maximum files to match a wildcard MAXWLD 102400 ckcdeb.h
234 Filespecs in MSEND command MSENDMAX 1024 ckuusr.h
235 Length for GOTO target label LBLSIZ 50 ckuusr.h
236 \fexecute() recursion depth limit CMDDEP 64 ckucmd.h
238 If you need to define a macro that is longer than CMDBL, you can break
239 the macro up into sub-macros or rewrite the macro as a command file. In
240 a pinch you can also redefine CMDBL and recompile C-Kermit. All of
241 these numbers represent tradeoffs: the bigger the number, the more
242 "powerful" Kermit in the corresponding area, but also the bigger the
243 program image and possibly disk footprint, and the longer it takes to
246 In the interactive command parser:
248 * EMACS- or VI-style command line editing is not supported.
249 * Editing keys are hardwired (Ctrl-U, Ctrl-W, etc).
251 If you interrupt C-Kermit before it has issued its first prompt, it
252 will exit. This means that you cannot interrupt execution of the
253 initialization file, or of an "application file" (file whose name is
254 given as the first command-line argument), or of an alternative
255 initialization file ("-y filename"), and get to the prompt. There is,
256 however, one exception to this rule: you *can* interrupt commands --
257 including TAKE commands -- given in the '-C "command list"'
258 command-line argument and -- if there were no action commands among the
259 command-line arguments -- you will be returned to the C-Kermit prompt.
260 So, for example, if you want to start C-Kermit in such a way that it
261 executes a command file before issuing its first prompt, and you also
262 want to be able to interrupt the command file and get to the prompt,
263 include a TAKE command for the desired command in the -C argument, for
266 kermit -C "take dial.scr"
268 At the command prompt, if you use the backslash (\) prefix to enter a
269 control character, space, or question mark into a command literally,
270 the backslash disappears and is replaced by the quoted character. If it
271 was a control character, it is shown as a circumflex (^). This allows
272 editing (backspace, delete, Ctrl-W) to work correctly even for control
275 Priot to C-Kermit 8.0, the only way to include a comma literally in a
276 macro definition -- as opposed to having it separate commands within
277 the definition -- is to enter its ASCII value (44) in backslash
280 DEFINE ROWS RUN MODE CO80\{44}\%1
282 In C-Kermit 8.0 you can use constructions like this:
284 DEFINE ROWS RUN MODE "CO80,\%1"
286 If you quote special characters in a filename (e.g. in the SEND
287 command), filename completion may seem to work incorrectly. For
288 example, if you have a file whose name is a*b (the name really contains
289 an asterisk), and you type "send a\\*<ESC>", the "b" does not appear,
290 nor will Ctrl-R redisplay the completed name correctly. But internally
291 the file name is recognized anyway.
293 Question-mark help does not work during execution of an ASKQ command.
294 The question marks are simply accepted as text.
296 In OUTPUT commands only, \B sends a BREAK signal, \L sends a Long BREAK
297 signal, and \N sends a NUL (ASCII 0). BREAK and Long BREAK are special
298 signals, not characters, and NUL is a character that normally cannot be
299 included in a C string, since it is the C string terminator. If you
300 really want to output a backslash followed by a B, an L, or an N (as is
301 needed to configure certain modems, etc), double the backslash, e.g.
302 "output \\B". In C-Kermit 7.0 or later, you can disarm and re-arm the
303 special OUTPUT-command escapes (\B, \L, and \N) with SET OUTPUT
304 SPECIAL-ESCAPES { OFF, ON }.
306 When using the command-line processor ("kermit -l /dev/tty00 -b 19200",
307 etc), note that in some cases the order of the command-line options
308 makes a difference, contrary to the expectation that order of
309 command-line options should not matter. For example, the -b option must
310 be given after the -l option if it is to affect the device specified in
315 [ [46]Top ] [ [47]Contents ] [ [48]Next ] [ [49]Previous ]
317 C-Kermit 7.0 and earlier do not support multiple sessions. When you SET
318 LINE (or SET PORT, same thing) to a new device, or SET HOST to a new
319 host, the previous SET LINE device or network host connection is
320 closed, resulting in hangup of the modem or termination of the network
321 connection. In windowing environments like HP-VUE, NeXTSTEP, Windows,
322 OS/2, etc, you can run separate copies of Kermit in different windows
323 to achieve multiple sessions.
325 To achieve multiple sessions through a single serial port (e.g. when
326 dialing up), you can install SLIP or PPP on your computer and then use
327 C-Kermit's TCP/IP support over the SLIP or PPP connection, assuming you
328 also have TCP/IP networking installed on your computer.
330 C-Kermit 8.0 has the same restriction on SET LINE and SET HOST
331 sessions: only one regular session (dialout, Telnet, etc) can be open
332 at a time. However, version 8.0 adds two new kinds of sessions: FTP and
333 HTTP; one or both of these can be open at the same as a regular
336 4. NETWORK CONNECTIONS
338 [ [50]Top ] [ [51]Contents ] [ [52]Next ] [ [53]Previous ]
342 The Unix C-Kermit 8.0.206 FTP client had the following bugs at the time
343 most of the 8.0.206 binaries were built for the C-Kermit 8.0 CDROM:
345 1. FTP MGET fails when directory segments contain wildcards, as in
346 "ftp mget */data/*.dat". Work around by doing a separate MGET for
347 each source directory.
348 2. FTP MGET can fail or produce random side effects if you have a
349 TMPDIR or CK_TMP environment variable definition in effect, or a
350 SET TEMP-DIRECTORY value, longer than 7 characters. Work around by
351 giving a SET TEMP-DIRECTORY command with a short value, such as
354 These two bugs are fixed in the source code that is included on the
355 CDROM, and also in Kermit 95 2.1.1. You can tell if a C-Kermit 8.0.206
356 binary has these fixes by typing SHOW VERSION; if it says "FTP Client,
357 8.0.200, 24 Oct 2002" it has the fixes; if the edit number is less that
358 200, it doesn't, in which case can build a new binary from the source
359 code (or contact us and we'll try to get get one for you).
361 Making TCP/IP Connections Can Take a Long Time
363 The most frequently asked question in many newsgroups is "Why does it
364 take such a long time to make a Telnet connection to (or from) my
365 (e.g.) Linux PC?" (this applies to Kermit as well as to regular Telnet
368 1. Most Telnet servers perform reverse DNS lookups on the client for
369 security and/or logging reasons. If the Telnet client's host cannot
370 be found by the server's local DNS server, the DNS request goes out
371 to the Internet at large, and this can take quite some time. The
372 solution to this problem is to make sure that both client and host
373 are registered in DNS.
374 2. C-Kermit itself performs reverse DNS lookups unless you tell it not
375 to. This is to allow C-Kermit to let you know which host it is
376 actually connected to in case you have made a connection to a "host
377 pool" (multihomed host). You can disable C-Kermit's reverse DNS
378 lookup with SET TCP REVERSE-DNS-LOOKUP OFF.
379 3. C-Kermit 7.0 and later strictly enforce Telnet protocol rules. One
380 such rule is that certain negotiations must be responded to. If
381 C-Kermit sends a such a negotiation and the host does not respond,
382 C-Kermit waits a long time for the reply (in case the network is
383 congested or the host is slow), but eventually will time out. To
384 eliminate the waits (and therefore risk possible protocol
385 mismatches -- or worse -- between Telnet client and server), tell
386 C-Kermit to SET TELNET WAIT OFF (or include the /NOWAIT switch with
391 In multiuser operating systems such as UNIX and VMS, TCP/IP Rlogin
392 connections are available only to privileged users, since "login" is a
393 privileged socket. Assuming you are allowed to use it in the first
394 place, it is likely to behave differently depending on what type of
395 host you are rlogging in to, due to technical reasons having to do with
396 conflicting interpretations of RFC793 (Out-Of-Band Data) and Rlogin
397 (RFC1122)... "Specifically, the TCP urgent pointer in BSD points to the
398 byte after the urgent data byte, and an RFC-compliant TCP urgent
399 pointer points to the urgent data byte. As a result, if an application
400 sends urgent data from a BSD-compatible implementation to an
401 [54]RFC-1122 compatible implementation then the receiver will read the
402 wrong urgent data byte (it will read the byte located after the correct
403 byte in the data stream as the urgent data byte)." Rlogin requires the
404 use of OOB data while Telnet does not. Therefore, it is possible for
405 Telnet to work between all systems while BSD and System V TCP/IP
406 implementations are almost always a bad mix.
410 On a TCP/IP TELNET connection, you should normally have PARITY set to
411 NONE and (except in VMS C-Kermit) FLOW-CONTROL also set to NONE. If
412 file transfer does not work with these settings (for example, because
413 the remote TELNET server only gives a 7-bit data path), use SET PARITY
414 SPACE. Do not use SET PARITY MARK, EVEN, or ODD on a TELNET connection
415 -- it interferes with TELNET protocol.
417 If echoing does not work right after connecting to a network host or
418 after dialing through a TCP/IP modem server, it probably means that the
419 TELNET server on the far end of the connection is executing the TELNET
420 protocol incorrectly. After initially connecting and discovering
421 incorrect echoing (characters are echoed twice, or not at all), escape
422 back, give the appropriate SET DUPLEX command (FULL or HALF), and then
423 CONNECT again. For a consistently misbehaving connection, you can
424 automate this process in a macro or TAKE file.
426 TELNET sessions are treated just like serial communications sessions as
427 far as "terminal bytesize" and "command bytesize" are concerned. If you
428 need to view and/or enter 8-bit characters during a TELNET session, you
429 must tell C-Kermit to SET TERMINAL BYTESIZE 8, SET COMMAND BYTESIZE 8,
432 If you SET TELNET DEBUG ON prior to making a connection, protocol
433 negotiations will be displayed on your screen. You can also capture
434 them in the debug log (along with everything else) and then extract
435 them easily, since all Telnet negotiations lines begin with (uppercase)
440 C-Kermit does not have its own built-in SSH client; instead, in the
441 Unix tradition, uses the external SSH client to do the SSH part, and
442 Kermit does its thing on top -- file transfer, scripting, etc. Under
443 certain circumstances that have not yet been identified, it sometimes
444 happens that after making an SSH connection from C-Kermit, logging out
445 from the remote host, and popping back to the local C-Kermit program,
446 subsequent SSH commands file with a message like "Network type not
447 supported". Starting a new copy of C-Kermit is the workaround.
449 5. MODEMS AND DIALING
451 [ [55]Top ] [ [56]Contents ] [ [57]Next ] [ [58]Previous ]
453 External modems are recommended because:
455 * They don't need any special drivers.
456 * They are less likely to interfere with normal operation of your
458 * You can use the lights and speaker to troubleshoot dialing.
459 * You can share them among all types of computers.
460 * You can easily turn them off and on when power-cycling seems
462 * They are more likely to have manuals.
464 Modems can be used by C-Kermit only when they are visible as or through
465 a regular serial port device. Certain modems can not be used in this
466 normal way on many kinds of computers: Winmodems, RPI modems,
467 Controllerless modems, the IBM Mwave, etc; all of these require special
468 drivers that perform some, most, or all of the modem's functions in
469 software. Such drivers are generally NOT available in UNIX or other
470 non-Windows (or non-OS/2, in the case of the Mwave) platforms.
472 In order to dial a modem, C-Kermit must know the modem's repertoire of
473 commands and responses. Each modem make and model is likely to have a
474 different repertoire. Since Kermit has no way of knowing which kind of
475 modem will be dialed, normally you have to tell it with a SET MODEM
478 set modem type usrobotics
483 In the early days, there was a wide variety of modems and command
484 languages. Nowadays, almost every modem uses the Hayes AT command set
485 (but with some differences in the details) and its startup
486 configuration includes error correction, data compression, and hardware
487 (RTS/CTS) flow control. As long as C-Kermit is capable of hardware flow
488 control (as it is on many, but not all, the platforms where it runs,
489 since some operating systems don't support it), the modem can be dialed
490 immediately, without lengthy configuration dialogs, and in fact this is
491 what SET MODEM TYPE GENERIC-HIGH-SPEED does. In C-Kermit 8.0,
492 GENERIC-HIGH-SPEED has become the default modem type, so now it is
493 usually possible to SET LINE, SET SPEED, and DIAL without having to
494 identify your modem. If this doesn't work, of course, then you might
495 have to fall back to the traditional method: Give a SET MODEM TYPE for
496 a specific modem first, then SET LINE, SET SPEED, and DIAL.
498 An important change in C-Kermit 6.0 is that when you give a SET MODEM
499 TYPE command to tell Kermit what kind of modem you have, Kermit also
500 sets a number of other modem-related parameters automatically from its
501 internal modem database. Thus, the order in which you give
502 modem-related commands is significant, whereas in prior releases they
503 could be given in any order.
505 In particular, MODEM SPEED-MATCHING is set according to whether the
506 modem is known to be capable of speed buffering. SET MODEM TYPE
507 HAYES-2400 automatically turns SPEED-MATCHING ON, because when the
508 Hayes 2400 reports a particular speed in its CONNECT message, that
509 means its interface speed has changed to that speed, and C-Kermit's
510 must change accordingly if it is to continue communicating. This might
511 cause some confusion if you use "set modem type hayes" for dialing a
512 more advanced type of modem.
514 The new default for flow control is "auto", meaning "do the right thing
515 for each type of connection". So (for example) if your version of
516 C-Kermit supports SET FLOW RTS/CTS and your modem also supports
517 RTS/CTS, then Kermit automatically sets its flow control to RTS/CTS and
518 set modem's flow control to RTS/CTS too before attempting to use the
521 For these reasons, don't assume that "set modem type hayes" should be
522 used for all modems that uses the Hayes AT command set. "set modem type
523 hayes" really does mean Hayes 1200 or 2400, which in turn means no
524 hardware flow control, and no speed buffering. This choice will rarely
525 work with a modern high-speed modem.
527 6. DIALING HINTS AND TIPS
529 [ [59]Top ] [ [60]Contents ] [ [61]Next ] [ [62]Previous ]
531 If you have a high-speed, error-correcting, data-compressing,
532 speed-buffering modem, you should fix the modem's interface speed as
533 high as possible, preferably (at least) four times higher than its
534 maximum connection (modulation) speed to allow compression to work at
535 full advantage. In this type of setup, you must also have an effective
536 means of flow control enabled between C-Kermit and the modem,
537 preferably hardware (RTS/CTS) flow control. On platforms that do not
538 support hardware flow control, it is usually possible to select
539 software flow control (Xon/Xoff), and C-Kermit will do its best to set
540 the modem for local Xon/Xoff flow control too (but then, of course,
541 Ctrl-S and Ctrl-Q characters can not be transmitted on the connection).
543 If you are having trouble dialing your modem, SET DIAL DISPLAY ON to
544 watch the dialing interactions between C-Kermit and your modem. Consult
545 Chapters 3-4 of [63]Using C-Kermit (2nd Ed) for modem-dialing
546 troubleshooting instructions. The following sections offer some
547 additional hints and tips.
551 If you want to dial a number that starts with #, you'll need to quote
552 the "#" character (as \# or \{35}), since it is also a comment
555 C-Kermit>dial #98765421-1-212-5551212 ; Looks like a comment
556 ?You must specify a number to dial
557 C-Kermit>dial \#98765421-1-212-5551212 ; Works OK
558 C-Kermit>dial =#98765421-1-212-5551212 ; This works too
560 When using a dialing directory, remember what happens if a name is not
563 C-Kermit>dial xyzcorp
564 Lookup: "xyzcorp" - not found - dialing as given
566 This normally does no harm, but some modems might behave strangely when
567 given dial strings that contain certain letters. For example, a certain
568 German modem treats any dial string that contains the letter "s" as a
569 command to fetch a number from its internal list, and replies OK to the
570 ATD command, which is normally not a valid response except for partial
571 dialing. To avoid this situation, use:
576 6.2. The Carrier Signal
578 Remember: In many C-Kermit implementations (depending on the underlying
579 operating system -- mostly Windows, OS/2, and System-V-based UNIX
580 versions, and in C-Kermit 7.0, also VMS), you can't CONNECT to a modem
581 and type the modem's dialing command (like "ATDT7654321") manually,
582 unless you first tell C-Kermit to:
584 SET CARRIER-WATCH OFF
586 This is because (in these implementations), the CONNECT command
587 requires the modem's Carrier Detect (CD) signal to be on, but the CD
588 signal doesn't come on until after dialing is complete. This
589 requirement is what allows C-Kermit to pop back to its prompt
590 automatically when the connection is hung up. See the description of
591 SET CARRIER-WATCH in "Using C-Kermit".
593 Similarly, if your dialed connection drops when CARRIER-WATCH is set to
594 AUTO or ON, you can't CONNECT back to the (now disconnected) screen to
595 see what might have happened unless you first SET CARRIER-WATCH OFF.
596 But sometimes not even SET CARRIER-WATCH OFF will help in this
597 situation: certain platforms (for example Unixware 2.1), once carrier
598 drops, won't let the application do i/o with the device any more. In
599 that case, if you want to use the device again, you have to CLOSE it
600 and OPEN it again. Or you can have Kermit do this for you automatically
601 by telling it to SET CLOSE-ON-DISCONNECT ON.
603 6.3. Dialing and Flow Control
605 Don't SET FLOW RTS/CTS if your modem is turned off, or if it is not
606 presenting the CTS signal. Otherwise, the serial device driver can get
607 stuck waiting for this signal to appear.
609 Most modern modems support RTS/CTS (if they support any hardware flow
610 control at all), but some computers use different RS-232 circuits for
611 the same purposes, e.g. DTR and CD, or DTR and CTS. In such cases, you
612 might be able to make your computer work with your modem by
613 appropriately cross-wiring the circuits in the cable connector, for
614 example the computer's DTR to the modem's RTS, and modem's CD to the
615 computer's CTS. HOWEVER, C-Kermit does not know you have done this. So
616 if you have (say) SET FLOW DTR/CD, C-Kermit will make no attempt to
617 tell the modem to use RTS/CTS. You probably did this yourself when you
618 configured the modem.
620 6.4. The Dial Timeout
622 If it takes your call longer to be completed than the timeout interval
623 that C-Kermit calculates, you can use the SET DIAL TIMEOUT command to
624 override C-Kermit's value. But beware: the modem has its own timeout
625 for completing the call. If it is a Hayes-like modem, C-Kermit adjusts
626 the modem's value too by setting register S7. But the maximum value for
627 S7 might be smaller than the time you need! In that case, C-Kermit sets
628 S7 to 0, 255, or other (modem-specific) value to signify "no timeout".
629 If Kermit attempts to set register S7 to a value higher than your
630 modem's maximum, the modem will say "ERROR" and you will get a "Failure
631 to initialize modem" error. In that case, use SET DIAL TIMEOUT to
632 override C-Kermit's calculation of the timeout value with the highest
633 value that is legal for your modem, e.g. 60.
635 6.5. Escape Sequence Guard Time
637 A "TIES" (Time-Independent Escape Sequence) modem does not require any
638 guard time around its escape sequence. The following text:
642 if sent through a TIES modem, for example because you were uploading
643 this file through it, could pop the modem back into command mode and
644 make it hang up the connection. Later versions of the Telebit T1600 and
645 T3000 (version LA3.01E firmware and later), and all WorldBlazers, use
648 Although the probability of "+++" appearing in a Kermit packet is
649 markedly lower than with most other protocols (see the [64]File
650 Transfer section below), it can still happen under certain
651 circumstances. It can also happen when using C-Kermit's TRANSMIT
652 command. If you are using a Telebit TIES modem, you can change the
653 modem's escape sequence to an otherwise little-used control character
654 such as Ctrl-_ (Control-Underscore):
658 A sequence of three consecutive Ctrl-_ characters will not appear in a
659 Kermit packet unless you go to extraordinary lengths to defeat more
660 than a few of Kermit's built-in safety mechanisms. And if you do this,
661 then you should also turn off the modem's escape-sequence recognition
666 But when escape sequence recognition is turned off, "modem hangup"
667 (<pause>+++<pause>ATH0<CR>) will not work, so you should also SET MODEM
668 HANGUP RS232-SIGNAL (rather then MODEM-COMMAND).
670 6.6. Adaptive Dialing
672 Some modems have a feature called adaptive dialing. When they are told
673 to dial a number using Tone dialing, they check to make sure that
674 dialtone has gone away after dialing the first digit. If it has not,
675 the modem assumes the phone line does not accept Tone dialing and so
676 switches to Pulse. When dialing out from a PBX, there is almost always
677 a secondary dialtone. Typically you take the phone off-hook, get the
678 PBX dialtone, dial "9" to get an outside line, and then get the phone
679 company's dialtone. In a situation like this, you need to tell the
680 modem to expect the secondary dialtone. On Hayes and compatible modems,
681 this is done by putting a "W" in the dial string at the appropriate
682 place. For example, to dial 9 for an outside line, and then 7654321,
685 SET PBX-OUTSIDE-PREFIX 9W
687 (replace "9" with whatever your PBX's outside-line prefix is).
691 Some phone companies are eliminating the busy signal. Instead, they
692 issue a voice message such as "press 1 to automatically redial until
693 the number answers, or...". Obviously this is a disaster for modem
694 calls. If your service has this feature, there's nothing Kermit can do
695 about it. Your modem will respond with NO CARRIER (after a long time)
696 rather than BUSY (immediately), and Kermit will declare the call a
697 failure, rather than trying to redial the same number.
701 There are two ways to hang up a modem: by turning off the serial port's
702 DTR signal (SET MODEM HANGUP-METHOD RS232-SIGNAL) or sending the modem
703 its escape sequence followed by its hangup command (SET MODEM
704 HANGUP-METHOD MODEM-COMMAND). If one doesn't work, try the other. If
705 the automatic hangup performed at the beginning of a DIAL command
706 causes trouble, then SET DIAL HANGUP OFF.
708 The HANGUP command has no effect when C-Kermit is in remote mode. This
709 is on purpose. If C-Kermit could hang up its own controlling terminal,
710 this would (a) most likely leave behind zombie processes, and (b) pose
713 If you DIAL a modem, disconnect, then SET HOST or TELNET, and then
714 HANGUP, Kermit sends the modem's hangup command, such as "+++ATHO".
715 There is no good way to avoid this, because this case can't reliably be
716 distinguished from the case in which the user does SET HOST
717 terminal-server, SET MODEM TYPE name, DIAL. In both cases we have a
718 valid modem type selected and we have a network connection. If you want
719 to DIAL and then later make a regular network connection, you will have
720 to SET MODEM TYPE NONE or SET DIAL HANGUP OFF to avoid this phenomenon.
724 [ [65]Top ] [ [66]Contents ] [ [67]Next ] [ [68]Previous ]
726 Watch out for terminal server's escape character -- usually a control
727 character such as Ctrl-Circumflex (Ctrl-^). Don't unprefix it in
730 Ciscos -- must often be told to "terminal download"... Cisco ASM models
731 don't have hardware flow control in both directions.
733 Many terminal servers only give you a 7-bit connection, so if you can't
734 make it 8-bit, tell Kermit to "set parity space".
736 The following story, regarding trouble transferring 8-bit files through
737 a reverse terminal server, was contributed by an Annex terminal server
740 Using C-Kermit on an HP 9000 712/80 running the HP-UX 10.00
741 operating system. The HP was connected to a Xylogics Annex
742 MICRO-ELS-UX R7.1 8 port terminal server via ethernet. On the second
743 port of the terminal server is an AT&T Paradyne 3810 modem, which is
744 connected to a telephone line. There is a program which runs on the
745 HP to establish a Telnet connection between a serial line on the
746 Annex and a character special file on the HP (/dev file). This is an
747 Annex specific program called rtelnet (reverse telnet) and is
748 provided with the terminal server software. The rtelnet utility runs
749 on top of the pseudo-terminal facility provided by UNIX. It creates
750 host-originated connections to devices attached ot Annex serial
751 ports. There are several command line arguments to be specified with
752 this program: the IP address of the terminal server, the number of
753 the port to attach to, and the name of the pseudo-device to create.
754 In addition to these there are options to tell rtelnet how to
755 operate on the connect: -b requests negotiation for Telnet binary
756 mode, -d turns on socket-leve debugging, -f enables "connect on the
757 fly" mode, -r removes the device-name if it already exists, etc. The
758 most important of these to be specified when using 8 data bits and
759 no parity, as we found out, was the -t option. This creates a
760 transparent TCP connection to the terminal server. Again, what we
761 assumed to be happening was that the rtelnet program encountered a
762 character sequence special to itself and then "eating" those kermit
763 packets. I think this is all of the information I can give you on
764 the configuration, short of the values associated with the port on
767 How to DIAL from a TCP/IP reverse terminal server (modem server):
769 1. (only if necessary) SET TELNET ECHO REMOTE
770 2. SET HOST terminal-server-ip-name-or-address [ port ]
771 3. SET MODEM TYPE modem-type
772 4. (only if necessary) SET DIAL HANGUP OFF
773 5. (for troubleshooting) SET DIAL DISPLAY ON
776 The order is important: SET HOST before SET MODEM TYPE. Since this is a
777 Telnet connection, serial-port related commands such as SET SPEED, SET
778 STOP-BITS, HANGUP (when MODEM HANGUP-METHOD is RS232), etc, have no
779 effect. However, in C-Kermit 8.0, if the modem server supports
780 [69]RFC-2217 Telnet Com-Port Control protocol, these commands do indeed
781 take effect at the server's serial port.
783 8. TERMINAL EMULATION
785 [ [70]Top ] [ [71]Contents ] [ [72]Next ] [ [73]Previous ]
787 Except for the Windows, OS/2, and Macintosh versions, C-Kermit does not
788 emulate any kind of terminal. Rather, it acts as a "semitransparent
789 pipe", passing the characters you type during a CONNECT session to the
790 remote host, and sending the characters received from the remote host
791 to your screen. Whatever is controlling your keyboard and screen
792 provides the specific terminal emulation: a real terminal, a PC running
793 a terminal emulator, etc, or (in the case of a self-contained
794 workstation) your console driver, a terminal window, xterm, etc.
796 Kermit is semitransparent rather than fully transparent in the
799 * During a TELNET ("set host") session, C-Kermit itself executes the
800 TELNET protocol and performs TELNET negotiations. (But it does not
801 perform TN3270 protocol or any other type of 3270 terminal
803 * If you have changed your keyboard mapping using SET KEY, C-Kermit
804 replaces the characters you type with the characters or strings
806 * If you SET your TERMINAL CHARACTER-SET to anything but TRANSPARENT,
807 C-Kermit translates your keystrokes (after applying any SET KEY
808 definitions) before transmitting them, and translates received
809 characters before showing them on your screen.
810 * If your remote and/or local TERMINAL CHARACTER-SET is an ISO 646
811 7-bit national character set, such as German, French, Italian,
812 Swedish, etc, or Short KOI used for Cyrillic, C-Kermit's CONNECT
813 command automatically skips over ANSI escape sequences to avoid
814 translating their characters. Only ANSI/ISO standard
815 (VT100/200/300-like) 7-bit escape sequence formats are supported
816 for this purpose, no proprietary schemes like H-P, Televideo,
818 * If your version of C-Kermit includes SET TERMINAL APC command, then
819 C-Kermit's CONNECT command will handle APC escape sequences if
820 TERMINAL APC is not set to OFF (which is the default).
822 You can make C-Kermit fully transparent by starting it with the -0
823 (dash zero) command-line option.
825 If you are running C-Kermit under a console driver, or in a terminal
826 window, that emulates the VT100, and use C-Kermit to log in to a VMS
827 system, the console driver or terminal window (not Kermit) is supposed
828 to reply to the "what are you?" query (ESC Z) from the VAX. If it
829 doesn't, and you can't make it do so, then you can (a) live with the
830 "unknown terminal" problem; (b) tell VMS to SET TERMINAL/DEVICE=VT100;
831 (c) program a key using SET KEY to send the appropriate sequence and
832 then punch the key at the right time; or (d) use the VMSLOGIN macro
833 that is defined in CKERMIT.INI to do this for you automatically.
835 SET SESSION-LOG { TEXT, BINARY }, which is effective in UNIX and AOS/VS
836 but not other C-Kermit versions, removes CR, DEL, NUL, XON, and XOFF
837 characters (Using C-Kermit neglects to mention that XON and XOFF are
838 removed). The TEXT-mode setting is ineffective during SCRIPT command
839 execution, as well as on X.25 connections.
843 [ [74]Top ] [ [75]Contents ] [ [76]Next ] [ [77]Previous ]
845 Except in the terminal-emulating versions, C-Kermit's key mapping
846 facilities are limited to normal "ASCII" keys, and cannot be used with
847 function keys, arrow keys, arcane key combinations, etc. Since C-Kermit
848 runs on such a wide variety of hardware platforms (including, for
849 example, more than 360 different UNIX platforms), it is not possible
850 for C-Kermit to support every conceivable keyboard under every release
851 of every UNIX (or VMS, or ...) product on every different kind of
852 computer possibly under all manner of different console drivers, even
853 if it had the means to do so.
855 In technical terms, C-Kermit uses the read() function to read
856 keystrokes, and read() returns a single byte (value 0 through 255).
857 C-Kermit's SET KEY function applies to these single-byte codes.
858 "Extended function" keys, such as F-keys, arrow keys, etc, usually
859 return either a 2-byte "scan code" or else a character string (such as
860 an escape sequence like "<ESC> O p"). In both cases, C-Kermit has no
861 way to tell the difference between such multibyte key values, and the
862 corresponding series of single-byte key values. This could only be done
863 by accessing the keyboard at a much lower level in a highly
864 platform-dependent manner, probably requiring tens of thousands of
865 lines of code to support even a sampling of the most popular
866 workstation / OS combinations.
868 However, most workstation console drivers (terminal emulation windows,
869 etc) include their own key-mapping facility. For example in AIX, the
870 AIXterm program (in whose window you would run C-Kermit) allows
871 rebinding of the F1-F12 keys to arbitrary strings. The same is true of
872 Xterm and DECterm windows, etc. Consult the technical documentation for
873 your workstation or emulator. See sample Xterm (Xmodmap) mappings in
874 the [78]Unix C-Kermit Hints and Tips document.
876 The SET KEY command (except in Kermit 95) does not allow a key
877 definition to be (or contain) the NUL (\0) character.
881 [ [79]Top ] [ [80]Contents ] [ [81]Next ] [ [82]Previous ]
883 C-Kermit 7.0 is the first release of C-Kermit to use fast (rather than
884 robust and therefore slow) protocol defaults: long packets, sliding
885 windows, control-character unprefixing, and streaming where possible.
886 This makes most transfers (partner willing) dramatically faster "out of
887 the box" but might break some combinations that worked before. If
888 transfers with C-Kermit 7.0 or later fail where transfers worked with
889 earlier C-Kermit versions, try the following (one at a time, in this
892 1. SET PREFIXING ALL: Disables control-character unprefixing.
893 2. SET STREAMING OFF: Disables streaming.
894 3. CAUTIOUS: Selects medium but cautious protocol settings.
895 4. ROBUST: this command reverts to the most conservative protocol
898 Execution of multiple file transfers by C-Kermit from a command file
899 when in remote mode might exhibit long delays between each transfer. To
900 avoid this, just include the command "SET DELAY 0" in your command file
901 before any of the file-transfer commands.
903 File transfer failures can occur for all sorts of reasons, most of them
904 listed in Chapter 10 of [83]Using C-Kermit. The following sections
905 touch on some that aren't.
907 The [84]C-Kermit 7.0 Release Notes document SEND /COMMAND as taking an
908 argument, but it doesn't. Instead of SEND /COMMAND:{some command}, use:
910 SEND /COMMAND [ other switches such as /AS-NAME: ] command [ arguments... ]
914 Watch out for laptops and their assorted power-saver features; for
915 example, a built-in modem's "auto timeout delay" hanging up the
916 connection in the middle of a file transfer. Most modems, even if they
917 have this feature, do not have it enabled by default. But if you
918 experience otherwise inexplicable disconnections in the midst of your
919 Kermit sessions, check the modem manual for such things as "idle
920 timeout", "auto timeout", etc, and add the command to disable this
921 feature to Kermit's init string for this modem.
925 If uploading a large file to an NFS-mounted disk fails (or is painfully
926 slow), try uploading it to a local disk (e.g. /tmp on Unix) and then
927 copying to the NFS disk later.
931 If you are dialing out and find that downloads work but uploads don't,
932 try again with a lower serial-port speed. Case in point: dialing out on
933 a certain PC from Linux at 115200 bps using a USR Courier 56K
934 "V.Everything" external modem and RTS/CTS flow control. Downloads
935 worked flawlessly, uploads stopped dead after the first few packets
936 were sent. The modem lights showed constant retraining (ARQ light
937 blinks slowly), and the CTS light was off 95% of the time, allowing
938 nothing to get through. Reducing the serial port speed to 57600 bps
939 made the problems go away. Evidently the PC in question has a very fast
940 serial port, since dialing the same modem with a different PC at 115200
941 bps works without incident.
943 10.4. TCP/IP Connections
945 If you have trouble transferring files over a TCP/IP connection, tell
946 Kermit to SET PARITY SPACE and try again. If that doesn't work, also
947 try a shorter packet length or smaller window size (to compensate for
948 certain well-known broken Telnet servers), and/or SET RELIABLE OFF.
950 10.5. Multihop Connections
952 If you have a multihop connection, with the interior nodes in CONNECT
953 mode (Kermit, Telnet, Rlogin, or any other), you can expect (a) file
954 transfer to be slower, and (b) the connection to be less transparent
955 (to control characters, perhaps to the 8th bit) than a more direct
956 connection. C-Kermit 7.0 and later have a "-0" (dash-zero) command-line
957 option to make it 100% transparent in cases where it is to be used in
962 The recovery feature (RESEND command) that was added in version 5A(190)
963 works only for binary-mode transfers. In order for this feature to be
964 useful at all, the default for SET FILE INCOMPLETE was changed from
965 DISCARD to KEEP. Otherwise an interrupted transfer would leave no
966 partial file behind unless you had remembered to change the default.
967 But now you have to pay closer attention to Kermit's messages to know
968 whether a transfer succeeded or failed -- previously, if it failed, the
969 file would not show up on the receiving end at all; in 5A(190) and
970 later, you'll get a partial file which could easily be mistaken for the
971 complete file unless you change the default back to DISCARD or read the
972 screen messages, or keep a transaction log.
974 10.7. Filename Collisions
976 SET FILE COLLISION BACKUP is the default. This means:
978 * If you send the same file lots of times, there will be many backup
979 files. There is no automatic mechanism within Kermit to delete
980 them, no notion of a "version retention count", etc, but you can
981 use the PURGE command to clean them up.
982 * If a file arrives that has the same name as a directory, the file
983 transfer fails because Kermit will not rename a directory. Send the
984 file with another name, or use SET FILE COLLISION RENAME.
985 * If the directory lacks write permission, the file transfer fails
986 even if you have write access to the file that is being backed up;
987 in that case, switch to SET FILE COLLISION OVERWRITE or APPEND, or
988 send to a different directory.
990 SET FILE COLLISION UPDATE depends on the date/time stamp in the
991 attribute packet. However, this is recorded in local time, not
992 Universal Time (GMT), and there is no indication of time zone. The time
993 is expressed to the precision of 1 second, but some file systems do not
994 record with this precision -- for example, MS-DOS records the file
995 date/time only to the nearest 2 seconds. This might cause update
996 operations to send more files than necessary.
998 (This paragraph does NOT apply to UNIX, where, as of C-Kermit 7.0,
999 C-Kermit pipes incoming mail and print material directly the mail or
1000 print program): When C-Kermit is receiving files from another Kermit
1001 program that has been given the MAIL or REMOTE PRINT command, C-Kermit
1002 follows the current filename collision action. This can be
1003 disconcerting if the action was (for example) BACKUP, because the
1004 existing file will be renamed, and the new file will be mailed (or
1005 printed) and then deleted. Kermit cannot temporarily change to RENAME
1006 because the file collision action occurs when the filename packet is
1007 received, and the PRINT or MAIL disposition only comes later, in the
1010 Watch out for SET FILE COLLISION RENAME, especially when used in
1011 conjunction with recovery. Recall that this option (which is NOT the
1012 default) renames the incoming file if a file already exists with the
1013 same name (the default is to rename the previously existing file, and
1014 store the incoming file with its own name). It is strongly recommended
1015 that you do not use SET FILE COLLISION RENAME if you ever intend to use
1016 the recovery feature:
1018 * When the file is first received by C-Kermit, its name is changed if
1019 another file already has the same name. When you RESEND the same
1020 file after a failure, C-Kermit will probably try to append the
1021 re-sent portion to the wrong file.
1022 * Assuming that you get RESEND to work with FILE COLLISION RENAME,
1023 C-Kermit, when receiving the remainder of the file during a RESEND
1024 operation, will report back the wrong name. Nothing can be done
1025 about this because the name is reported back before the receiving
1026 Kermit program finds out that it is a recovery operation.
1028 Also watch out for DISABLE DELETE, since this implicitly sets FILE
1029 COLLISION to RENAME. And note tht DELETE is DISABLEd automatically any
1030 time you Kermit is in local mode (i.e. it makes a connection). Also
1031 note that for purposes of DISABLE and ENABLE, "set host *" connections
1032 do not count as local mode even though, strictly speaking, they are.
1036 When referring to foreign MS-DOS, Windows, Atari ST, OS/2, or other
1037 file specifications that contain backslash characters in a C-Kermit
1038 command, you might have to double each backslash, for example:
1040 C-Kermit>get c:\\directory\\foo.txt
1042 This is because backslash is used in C-Kermit commands for introducing
1043 special character codes, variables, functions, etc.
1047 If attempting to cancel local-mode file reception at a very early stage
1048 (i.e. before data packets are exchanged) with X or Z does not work, use
1049 E or Ctrl-C instead, or wait until the first data packets are sent.
1051 If you cancel a transfer that is underway using X or Z, and a lot of
1052 window slots are in use, it might take a while for the cancellation to
1053 take effect, especially if you do this on the receiving end; that's
1054 because a lot of packets might already be on their way to you. In that
1055 case, just be patient and let Kermit "drain" them.
1057 If C-Kermit is sending a file, remote-mode packet-mode breakout (three
1058 consecutive Ctrl-C's by default) is not effective until after C-Kermit
1059 sends its first packet. If C-Kermit is receiving a file or is in server
1060 mode, it is effective right away. In the former case, the SET DELAY
1061 value determines the earliest time at which you can break out of packet
1064 10.10. Partner Peculiarities
1066 When one or both partners is on an SCO operating system such as OSR5,
1067 you might issue the command:
1071 to disable character-set conversion by the terminal driver. Similarly
1076 When using C-Kermit to transfer files with the HP48SX calculator, you
1077 must SET FLOW NONE. The HP48SX does not support flow control, and
1078 evidently also becomes confused if you attempt to use it. You might
1079 also need to use SET SEND PAUSE 100 (or other number). For greater
1080 detail about transferring files the HP-48, see:
1082 [85]http://www.columbia.edu/kermit/hp48.html
1084 Some communication programs have errors in their implementation of
1085 Kermit attribute packets. If you get an error message from your
1086 communication program like "Attribute error", tell C-Kermit to SET
1087 ATTRIBUTES OFF. Better yet, switch to a real Kermit program.
1089 Some communication software claims to implement Kermit sliding windows,
1090 but does so incorrectly. If sliding window transfers fail, set
1091 C-Kermit's window size to the smallest one that works, for example, SET
1094 For lots more detail about how to cope with defective Kermit partners,
1097 * [86]Coping with Faulty Kermit Implementations (C-Kermit 7.0 and
1099 * [87]Coping with Broken Kermit Partners (C-Kermit 8.0 and later).
1101 The UNIX version of C-Kermit discards carriage returns when receiving
1102 files in text mode. Thus, "bare" carriage returns (sometimes used to
1103 achieve overstriking) are lost.
1105 11. SCRIPT PROGRAMMING
1107 [ [88]Top ] [ [89]Contents ] [ [90]Previous ]
1109 11.1. Comments Versus the SCRIPT Command
1111 Remember that ";" and "#" introduce comments when (a) they are the
1112 first character on the line, or (b) they are preceded by at least one
1113 blank or tab within a line. Thus constructions like:
1118 must be coded using backslash notation to keep the data from being
1121 INPUT 5 \59 ; 59 is the decimal ASCII code for ";"
1122 SCRIPT ~0 \35--#--# ; 43 is the decimal ASCII code for "#"
1126 INPUT 5 \; ; Just quote the semicolon
1127 SCRIPT ~0 \#--#--# ; Just quote the "#"
1129 11.2. Alphabetic Case and the INPUT Command
1131 INPUT and MINPUT caseless string comparisons do not work for non-ASCII
1132 (international) characters. Workaround: SET INPUT CASE OBSERVE. Even
1133 then, the "lexically less than" and "lexically greater than" operations
1134 (IF LLT, IF LGT) probably won't work as expected. The same is true for
1135 the case-conversion functions \Flower() and \Fupper(). C-Kermit does
1136 not know the collating sequence for different character sets and
1137 languages. (On the other hand, it might work depending on such items as
1138 how Kermit was linked, whether your operating supports "locales", etc)
1140 11.3. NUL (0) Characters in C-Kermit Commands
1142 You can't include a NUL character (\0) in C-Kermit command text without
1143 terminating the character string in which it appears. For example:
1145 echo In these brackets [\0] is a NUL
1147 will echo "In these brackets [". This applies to ECHO, INPUT, OUTPUT,
1148 and all other commands (but you can represent NUL by "\N" in an OUTPUT
1149 string). This is because C-language strings are terminated internally
1150 by the NUL character, and it allows all of C-Kermit's string comparison
1151 and manipulation functions to work in the normal "C" way.
1169 INPUT operations discard and ignore NUL characters that arrive from the
1170 communication device, meaning that they do not figure into matching
1171 operations (e.g. A<NUL>B matches AB); they are not deposited in the
1172 INPUT buffer (\v(input)); and they are not counted in \v(incount), with
1175 1. An arriving NUL character restarts the INPUT SILENCE timer.
1176 2. An arriving NUL character terminates the INPUT command with the
1177 SUCCESS condition if the INPUT command was given an empty search
1178 string. In this case \v(incount) is set to 1.
1180 Also, the \v(inchar) variable is null (completely empty) if the last
1181 INPUT character was NUL. That is, there is no way to tell only by
1182 looking at \v(inchar) the difference between a NUL that was INPUT and
1183 no INPUT at all. If the INPUT command succeeded but \v(inchar) is
1184 empty, then a NUL character was input. Also, \v(incount) will be set to
1187 Here's a sample script fragment to read characters, possibly including
1188 NUL, from the communication connection and write them to a file:
1191 input 1 ; read one byte
1192 if fail break ; timed out or connection closed
1193 fwrite /char \%c \v(inchar) ; record the byte
1196 This works because when \v(inchar) is NUL, that's equivalent to FWRITE
1197 /CHAR having no text argument at all, in which case it writes a NUL
1200 \v(incount) and \v(inchar) are NOT affected by the CLEAR command.
1202 11.4. \ffiles() and \fnextfile() Peculiarities
1204 The following script program:
1206 for \%i 1 \ffiles(oofa.*) 1 {
1210 did not work as expected in C-Kermit 6.0 and earlier but does work in
1211 C-Kermit 7.0 and later.
1213 11.5. Commands That Have Only Local Effect
1215 Certain settings are local to each command level, meaning that
1216 subordinate command levels (macros or command files) can change them
1217 without affecting their values at higher command levels. When a new
1218 command level is invoked, the value is inherited from the previous
1219 level. These settings are:
1229 This arrangement allows CASE, TIMEOUT, and ERROR settings, which are
1230 used to control automatic exit from a command file or macro upon error,
1231 to be automatically restored when the command file or macro exits.
1233 The COUNT variable follows this rule too, which permits nested SET
1234 COUNT / IF COUNT loops, as in this example in which the inner loop
1235 counts down from the current COUNT value of the outer loop (try it):
1237 DEFINE INNER WHILE COUNT { WRITE SCREEN { Inner:}, SHOW COUNT }
1239 WHILE COUNT { WRITE SCREEN Outer:, SHOW COUNT, DO INNER }
1241 Keep in mind that an inferior command level cannot manipulate the COUNT
1242 value held by a higher level. For example:
1244 DEFINE OOFA SHOW COUNT, IF COUNT GOTO LOOP
1250 results in an infinite loop; the COUNT value remains at 5 because it is
1251 never decremented at the same level at which it was set.
1253 11.6. Literal Braces in Function Calls
1255 Since braces are used in function calls to indicate grouping, there is
1256 no way to pass literal braces to the function itself. Solution: Define
1257 a variable containing the string that has braces. Example:
1260 echo \fsubstring(\%a)
1263 If the string is to start with a leading brace and end with a closing
1264 brace, then double braces must appear around the string (which itself
1265 is enclosed in braces):
1267 define \%a {{{foo}}}
1268 echo \fsubstring(\%a)
1271 This also works for any other kind of string:
1273 define \%a {{ab{cd}}
1274 echo \fsubstring(\%a)
1277 11.7. Defining Variables on the C-Kermit Command Line
1279 To define variables on the C-Kermit command line, use the -C
1280 command-line option with one or more DEFINE or ASSIGN commands. Note
1281 that the C-Kermit command line must cope with the quoting rules of your
1284 kermit -C "define \\%a foo, define phonenumber 7654321"
1286 In this case we follow UNIX quoting rules by doubling the backslash.
1287 Once C-Kermit starts, the \%a and \m(phonenumber) variables are defined
1288 as indicated and can be used in the normal way.
1290 In DOS or Windows or OS/2 the command would be:
1292 kermit -C "define \%%a foo, define phonenumber 7654321"
1294 Here we need to double the percent sign rather than the backslash
1295 because of DOS shell quoting rules.
1297 11.8. Per-Character Echo Check with the OUTPUT Command
1299 Sometimes the OUTPUT command must be used to send commands or data to a
1300 device in "echoplex" mode, meaning that characters must be sent one at
1301 a time, and the next character can not be sent until the echo from the
1302 previous one has been received. For example, a certain PBX might have
1303 this characteristic. Let's say a Kermit script is used to program the
1304 PBX. If characters are sent too fast, they can be lost. It would seem
1307 SET OUTPUT PACING milliseconds
1309 could be used to take care of this, but the pacing interval is constant
1310 and must be set large enough to allow even the slowest echo to finish.
1311 If the script is large (an actual example is 14,000 lines long), this
1312 can cause it to take hours longer than it needs to.
1314 Here is a macro you can use to OUTPUT a string in an Echoplex
1320 for \%i 1 \flen(\%*) 1 {
1321 asg \%c \fsubstr(\%*,\%i,1)
1327 C-Kermit 7.0 or later is required.
1329 It sends one character at a time and then waits up to 2 seconds for the
1330 character to be echoed back, but continues to the next character as
1331 soon as the echo appears, so no time is wasted. You can add an IF FAIL
1332 clause after the INPUT in case you want to do something special about
1333 failure to detect an echo within the timeout period. Obviously you can
1334 also change the 2-second limit, and adjust the script in any other
1337 11.9. Scripted File Transfer
1339 Sometimes a user complains that when she makes a connection by hand,
1340 logs in, and transfers a file, there are no problems, but when she
1341 scripts the the exact same sequence, the file transfer always fails
1342 after a few packets. Here's a scenario where this can happen:
1344 1. Upon logging in to the remote computer, it sends a "What Are You?"
1346 2. When you log in interactively, your terminal emulator sends the
1347 response. This is invisible to you; you don't know it's happening.
1348 3. When you script the login, and begin a file transfer immediately
1349 upon logging in, the host still sends the "What Are You?" sequence.
1350 Kermit's INPUT ECHO setting is ON by default, so the escape
1351 sequence passes through to the terminal, and the terminal sends its
1352 response. But by this time Kermit has already started the file
1354 4. By default, the local Kermit program examines the keyboard for
1355 interruption characters between every packet. The "What Are You"
1356 response is sitting in the keyboard buffer. Eventually Kermit will
1357 read a character such as "c" that is a valid interruption
1358 character, and the file transfer stops with "User canceled".
1360 The right way to handle this situation is to have your look for the
1361 "What Are You?" sequence and send the response itself, as described in
1362 Using C-Kermit, pp.429-431. Or you can work around it by telling the
1363 local Kermit to "set input echo off" and/or "set transfer interruption
1366 11.10. Hexadecimal arithmetic...
1368 C-Kermit can do both integer and floating-point arithmetic, in both
1369 ordinary algebraic notation and in Lisp S-Expression notation. All
1370 arithmetic operators and functions operate only on decimal numbers. It
1371 is possible, however, to write scripts that operate on hexadecimal
1372 numbers. This is done by converting them to decimal prior to any
1373 arithmetic operations, and then converting them back to hexadecimal for
1376 ; EVALUATE is a command that evaluates an arithmetic expression.
1377 ; See HELP EVALUATE for details. This is just for demonstration.
1378 ; Arithmetic expressions can be used in any context where a number
1379 ; can be used. Also, the special notation:
1381 ; .\%a ::= expression
1383 ; evaluations the expression and assigns the result to the variable.
1385 .\%a := fffe ; Set variable to hex value
1386 set eval old ; See HELP EVAL
1387 eval \fhex2n(\%a) ; Show value of variable
1388 eval \fhex2n(\%a) + 1 ; Show value of expression
1389 eval \fhex2n(\%a) + 2 ; Show value of expression
1390 .\%x ::= \fhex2n(\%a) + 1 ; Assign value of expression to variable
1391 echo \fn2hex(\%x) ; Display variable's value in hex
1392 .\%x ::= \fhex2n(\%a) + 2 : Ditto
1394 .\%x ::= \fhex2n(\%a) | \fhex2n(ffff) ; Similarly for logical OR
1396 .\%x ::= \fhex2n(\%a) & \fhex2n(ffff) ; and logical AND
1399 By the way, you might be tempted to use Kermit's \xnn notation to plug
1400 hex numbers into arithmetic expressions but this doesn't work. That
1401 notation is strictly for bytes (hex representation of character
1402 values), not for numbers.
1406 Escape sequences (or any strings that contain control characters) can't
1407 be used as labels, GOTO targets, or SWITCH cases.
1409 [ [91]Top ] [ [92]Contents ] [ [93]C-Kermit Home ] [ [94]C-Kermit 8.0
1410 Overview ] [ [95]Kermit Home ]
1411 __________________________________________________________________
1413 C-Kermit 8.0 Unix Hints and Tips / [96]The Kermit Project /
1414 [97]kermit@columbia.edu / 30 June 2011
1418 1. http://www.columbia.edu/
1419 2. mailto:kermit@columbia.edu
1420 3. http://www.columbia.edu/kermit/index.html
1421 4. http://www.columbia.edu/kermit/k95.html
1422 5. http://www.columbia.edu/kermit/ckermit.html
1423 6. http://www.columbia.edu/kermit/ckscripts.html
1424 7. http://www.columbia.edu/kermit/current.html
1425 8. http://www.columbia.edu/kermit/whatsnew.html
1426 9. http://www.columbia.edu/kermit/faq.html
1427 10. http://www.columbia.edu/kermit/support.html
1428 11. http://www.columbia.edu/kermit/ckcbwr.html
1429 12. http://www.columbia.edu/kermit/ckubwr.html
1430 13. http://www.columbia.edu/kermit/k95.html
1431 14. http://www.columbia.edu/kermit/ckermit.html
1432 15. http://www.columbia.edu/kermit/ckututor.html
1433 16. http://www.columbia.edu/kermit/ckcbwr.html#x0
1434 17. http://www.columbia.edu/kermit/ckcbwr.html#x1
1435 18. http://www.columbia.edu/kermit/ckcbwr.html#x2
1436 19. http://www.columbia.edu/kermit/ckcbwr.html#x3
1437 20. http://www.columbia.edu/kermit/ckcbwr.html#x4
1438 21. http://www.columbia.edu/kermit/ckcbwr.html#x5
1439 22. http://www.columbia.edu/kermit/ckcbwr.html#x6
1440 23. http://www.columbia.edu/kermit/ckcbwr.html#x7
1441 24. http://www.columbia.edu/kermit/ckcbwr.html#x8
1442 25. http://www.columbia.edu/kermit/ckcbwr.html#x9
1443 26. http://www.columbia.edu/kermit/ckcbwr.html#x10
1444 27. http://www.columbia.edu/kermit/ckcbwr.html#x11
1445 28. http://www.columbia.edu/kermit/ckcbwr.html#top
1446 29. http://www.columbia.edu/kermit/ckcbwr.html#contents
1447 30. http://www.columbia.edu/kermit/ckcbwr.html#x2
1448 31. http://www.columbia.edu/kermit/ckcbwr.html#top
1449 32. http://www.columbia.edu/kermit/ckcbwr.html#contents
1450 33. http://www.columbia.edu/kermit/ckcbwr.html#x2
1451 34. http://www.columbia.edu/kermit/ck60manual.html
1452 35. http://www.columbia.edu/kermit/ckermit2.html
1453 36. http://www.columbia.edu/kermit/ck60manual.html
1454 37. http://www.columbia.edu/kermit/ckermit80.html#x5
1455 38. http://www.columbia.edu/kermit/ckermit80.html
1456 39. http://www.columbia.edu/kermit/ckermit80.html#x2.2
1457 40. http://www.columbia.edu/kermit/ckermit80.html#x8.7.2
1458 41. http://www.columbia.edu/kermit/ckermit80.html#x9
1459 42. http://www.columbia.edu/kermit/ckcbwr.html#top
1460 43. http://www.columbia.edu/kermit/ckcbwr.html#contents
1461 44. http://www.columbia.edu/kermit/ckcbwr.html#x3
1462 45. http://www.columbia.edu/kermit/ckcbwr.html#x1
1463 46. http://www.columbia.edu/kermit/ckcbwr.html#top
1464 47. http://www.columbia.edu/kermit/ckcbwr.html#contents
1465 48. http://www.columbia.edu/kermit/ckcbwr.html#x4
1466 49. http://www.columbia.edu/kermit/ckcbwr.html#x2
1467 50. http://www.columbia.edu/kermit/ckcbwr.html#top
1468 51. http://www.columbia.edu/kermit/ckcbwr.html#contents
1469 52. http://www.columbia.edu/kermit/ckcbwr.html#x5
1470 53. http://www.columbia.edu/kermit/ckcbwr.html#x3
1471 54. ftp://ftp.isi.edu/in-notes/rfc1122.txt
1472 55. http://www.columbia.edu/kermit/ckcbwr.html#top
1473 56. http://www.columbia.edu/kermit/ckcbwr.html#contents
1474 57. http://www.columbia.edu/kermit/ckcbwr.html#x6
1475 58. http://www.columbia.edu/kermit/ckcbwr.html#x4
1476 59. http://www.columbia.edu/kermit/ckcbwr.html#top
1477 60. http://www.columbia.edu/kermit/ckcbwr.html#contents
1478 61. http://www.columbia.edu/kermit/ckcbwr.html#x7
1479 62. http://www.columbia.edu/kermit/ckcbwr.html#x5
1480 63. http://www.columbia.edu/kermit/ck60manual.html
1481 64. http://www.columbia.edu/kermit/ckcbwr.html#x10
1482 65. http://www.columbia.edu/kermit/ckcbwr.html#top
1483 66. http://www.columbia.edu/kermit/ckcbwr.html#contents
1484 67. http://www.columbia.edu/kermit/ckcbwr.html#x8
1485 68. http://www.columbia.edu/kermit/ckcbwr.html#x6
1486 69. ftp://ftp.isi.edu/in-notes/rfc2217.txt
1487 70. http://www.columbia.edu/kermit/ckcbwr.html#top
1488 71. http://www.columbia.edu/kermit/ckcbwr.html#contents
1489 72. http://www.columbia.edu/kermit/ckcbwr.html#x9
1490 73. http://www.columbia.edu/kermit/ckcbwr.html#x7
1491 74. http://www.columbia.edu/kermit/ckcbwr.html#top
1492 75. http://www.columbia.edu/kermit/ckcbwr.html#contents
1493 76. http://www.columbia.edu/kermit/ckcbwr.html#x10
1494 77. http://www.columbia.edu/kermit/ckcbwr.html#x8
1495 78. http://www.columbia.edu/kermit/ckubwr.html
1496 79. http://www.columbia.edu/kermit/ckcbwr.html#top
1497 80. http://www.columbia.edu/kermit/ckcbwr.html#contents
1498 81. http://www.columbia.edu/kermit/ckcbwr.html#x11
1499 82. http://www.columbia.edu/kermit/ckcbwr.html#x9
1500 83. http://www.columbia.edu/kermit/ck60manual.html
1501 84. http://www.columbia.edu/kermit/ckermi70.htm
1502 85. http://www.columbia.edu/kermit/hp48.html
1503 86. http://www.columbia.edu/kermit/ckermit70.html#x4.22
1504 87. http://www.columbia.edu/kermit/ckermit80.html#x15
1505 88. http://www.columbia.edu/kermit/ckcbwr.html#top
1506 89. http://www.columbia.edu/kermit/ckcbwr.html#contents
1507 90. http://www.columbia.edu/kermit/ckcbwr.html#x10
1508 91. http://www.columbia.edu/kermit/ckcbwr.html#top
1509 92. http://www.columbia.edu/kermit/ckcbwr.html#contents
1510 93. http://www.columbia.edu/kermit/ckermit.html
1511 94. http://www.columbia.edu/kermit/ck80.html
1512 95. http://www.columbia.edu/kermit/index.html
1513 96. http://www.columbia.edu/kermit/index.html
1514 97. mailto:kermit@columbia.edu