📄 rfc2839.txt
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. Reception of files into directories or devices to which write access is allowed. . The ability to display a file on the client's screen. . Ability to list files. . Ability to change its working (default) directory. . Ability to delete files to which write or delete access is allowed. . Ability to rename and copy files . Ability to create and remove directories. . The ability to route received files to a specified printer, or to send them as email to a specified address list. . Client control of server parameter settings, within limits established by the server system administrator. . Transmission of variables from client to server or vice versa. . Remote and local script execution. . Remote and local procedure execution.da Cruz & Altman Informational [Page 14]RFC 2839 Internet Kermit Service May 2000 File transfer features include: . Kermit text-mode transfers incorporate not only record-format conversion, but also character-set translation; . Kermit can switch automatically between text and binary mode on a per-file basis when sending groups of files. . A selection of file collision options, including "make backup copy of existing file and accept incoming file", "reject incoming file", "accept incoming file only if newer than existing file", etc. . Numerous methods for selecting the files to be transferred, including pattern matching, lists of filenames (or patterns), exception lists, date and/or size ranges, etc. . Filename conversion and file renaming. . Automatic directory creation if elected and enabled. . Standard mechanisms for directory traversal, allowing transmission of entire directory trees or other file hierarchies even between unlike file systems such as VMS, UNIX, and Windows. . Atomic file movement: optionally, the source file can be deleted (or renamed, or moved) when and only when it has been transferred successfully. . Kermit can retain file attributes including time stamps and permissions (at the user's or system administrator's discretion), even between unlike platforms; . Recovery of interrupted transfers from the point of failure. . File-transfer pipes and filters. Script programming features include: . Macros with parameter substitution. . Built-in and user-defined variables and arrays, with global or local scope.da Cruz & Altman Informational [Page 15]RFC 2839 Internet Kermit Service May 2000 . Built-in and user-defined functions. Built-in functions include: - String functions - Arithmetic functions - Date / time functions - File functions . Input search for multiple simultaneous targets. . IF-ELSE, WHILE, FOR, SWITCH, GOTO, C-like block structure. . Every command returns a completion status that may be tested and used as a basis for subsequent actions.5.3. User Interface The Internet Kermit Service uses the Kermit command and script language, as implemented in Columbia University's C-Kermit communication software [CKB]. This program and its command language are portable to all known varieties of UNIX, as well as to Windows 95/98/NT, OS/2, Digital (Open)VMS, Stratus VOS, Data General AOS/VS, Plan 9, OS-9, QNX, the Commodore Amiga, and other platforms. The C-Kermit command language is a superset of that of other Kermit software programs including MS-DOS Kermit for DOS and Windows 3.x, IBM Mainframe Kermit for VM/CMS, MVS/TSO, CICS, and MUSIC, PDP-11 Kermit for RT-11, RSTS/E, RSX-11, and IAS, and dozens of other Kermit programs. It is far beyond the scope of this document to enumerate, let alone describe, the commands and services of C-Kermit; this is the subject of a 600-page book [CKB], augmented by hundreds of pages of online material. A brief overview is included here. Commands are based on English words. There is no plan at present to support other natural languages (Italian, Portuguese, Norwegian, Russian, Hebrew, Japanese, Cherokee, etc) as alternative bases for command words, since this would reduce the portability of scripts. However, since the command language includes a macro capability, macros may be defined to provide selected commands in different languages if desired. Certain commands can apply either locally or remotely, for example "CD" (Change Directory). The convention is to prefix the command with the word REMOTE if it is to apply remotely. Example: "cd foo" changes to the "foo" directory on the computer where the command was given; "remote cd foo" sends a Kermit packet to the Kermit server requesting it to change its directory to "foo". The commands in this category include:da Cruz & Altman Informational [Page 16]RFC 2839 Internet Kermit Service May 2000 ASSIGN <variable> <value> Assign a value to a variable. CD <directory> Change working directory. COPY <files> <destination> Copy file(s) DELETE <files> Delete file(s) DIRECTORY [ <pattern> ] List file(s) EXIT Exit HELP [ <topic-or-command> ] Display help text MKDIR <directory> Create a directory PRINT <files> Print file(s) PWD Print working directory RENAME <old> <new> Rename file(s) RMDIR <directory> Remove a directory SET <parameter> <value> Change a parameter's value TYPE <file> Display the contents of a file As a convenience, REMOTE commands also have short synonyms: RASSIGN, RCD, RCOPY, RDELETE, and so forth. The basic file transfer commands are: SEND [ modifiers ] <files> Send file(s) (to server) GET [ modifiers ] <files> Get file(s) (from server) These commands take a file name, pattern, or list, plus various optional modifiers, including transfer mode specifiers (text, binary), file selectors (date, size, exception list), aliasing, name and path options, disposition specifiers, and so on. In addition to the commands listed above, the following commands are sent by the client to the server: REMOTE QUERY Get value of variable or procedure BYE Log out and close the connection FINISH Request the server leave server mode Like all Kermit client/server commands, these can be disabled if desired. Of course there are numerous other commands with purely local effect, such as the many scripting commands. These, plus all the commands above, are fully documented in [CKB]. The repertoire grows over time, but never in a way that invalidates existing scripts. The system administrator can allow or forbid access to any of these features, and to the command language as a whole. In the latter case, the IKS may be accessed only as a Kermit server, by giving commands to the client.da Cruz & Altman Informational [Page 17]RFC 2839 Internet Kermit Service May 20006. REFERENCES [TKO] Altman, J. and F. da Cruz, "Telnet Kermit Option", RFC 2840, May 2000. [BCP] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [KER] da Cruz, Frank, "Kermit, A File Transfer Protocol", Digital Press/ Butterworth Heinemann, Newton, MA (1987). 379 pages, ISBN 0-932376-88-6. [CKB] da Cruz, Frank, and Christine M. Gianone, "Using C-Kermit", Second Edition, Digital Press / Butterworth-Heinemann, Woburn, MA (1997). 622 pages, ISBN 1-55558-164-1. [CMG] Gianone, Christine M., "Using MS-DOS Kermit", Second Edition, Digital Press / Butterworth-Heinemann, Woburn, MA (1992). 345 pages, ISBN 1-55558-082-3. [K95] Gianone, Christine M., and Frank da Cruz, "Kermit 95", Manning Publications, Greenwich CT, (1996). 88 pages, ISBN 1-884777- 14-7. [PRF] Huggins, James K., "Kermit Protocol - Formal Specification and Verification", in Boerger, E., "Specification and Validation Methods", Oxford University Press (1995). ISBN 0-19-853854-5. [FTP] Postel, J. and J. Reynolds, "File Transfer Protocol (FTP)", STD 9, RFC 959, October 1985. [TEL] Postel, J. and J. Reynolds, "Telnet Protocol Specification", STD 8, RFC854, May 1983, et seq.; "Telnet Option Specification", STD 8, RFC855, May 1983, et seq. [IAN] Internet Assigned Numbers Authority: http://www.iana.org/numbers.html http://www.iana.org/assignment/port-numbersda Cruz & Altman Informational [Page 18]RFC 2839 Internet Kermit Service May 20007. AUTHORS' ADDRESSES Frank da Cruz EMail: fdc@columbia.edu Jeffrey E. Altman EMail:jaltman@columbia.edu The Kermit Project Columbia University 612 West 115th Street New York NY 10025-7799 USA http://www.columbia.edu/kermit/ http://www.kermit-project.org/da Cruz & Altman Informational [Page 19]RFC 2839 Internet Kermit Service May 20008. Full Copyright Statement Copyright (C) The Internet Society (2000). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.Acknowledgement Funding for the RFC Editor function is currently provided by the Internet Society.da Cruz & Altman Informational [Page 20]
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