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Note: This introduction is aimed at providing an internet user with the basic information they need to be able to upload and download files across the internet. It is not a technical discussion on the algorithms involved in compression. Coverage of compression theory can be found in almost every computer science data structures textbook. |
C:\> pkzip
PKZIP (R) FAST! Create/Update Utility Version 2.04g 02-01-93
Copr. 1989-1993 PKWARE Inc. All Rights Reserved. Shareware Version
PKZIP Reg. U.S. Pat. and Tm. Off. Patent No. 5,051,745
PKZIP /h[1] for basic help PKZIP /h[2|3|4] for other help screens.
Usage: PKZIP [options] zipfile [@list] [files...]
Simple Usage: PKZIP zipfile file(s)...
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Program ----------------- | |
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New zipfile to create ---------- |
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File(s) you wish to compress ----------
The above usage is only a very basic example of PKZIP's capability.
Press 2 for more options (including spanning & formatting), press 3 for
advanced options, 4 for trouble shooting options, any other key to quit help.
If you use PKZIP on a regular basis you are strongly encouraged to register
it. With a full registration of US $47.00 you will receive a comprehensive
printed manual, the latest version of PKZIP, PKUNZIP & PKSFX software, and
when available, the next version of the software. See the documentation for
commercial and distribution licensing info. Send check or money order to:
PKWARE, Inc.
9025 N. Deerwood Drive
Brown Deer, WI 53223
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GZIP.EXE GNU Zip for MSDOS |
SQZ.EXE Current version: SQZ1083E.EXE |
ARC.EXE Current version: PK361.EXE |
LHA.EXE Current version: LHA213.EXE |
% gzip -h gzip 1.2.2 (17 Jun 93) usage: gzip [-cdfhlLnrtvV19] [-S suffix] [file ...] -c --stdout write on standard output, keep original files unchanged -d --decompress decompress -f --force force overwrite of output file and compress links -h --help give this help -l --list list .gz file contents -L --license display software license -n --no-name do not save or restore the original name -q --quiet suppress all warnings -r --recurse recurse through directories -S .suf --suffix .suf use suffix .suf instead of .gz -t --test test compressed file integrity -v --verbose verbose mode -V --version display version number -1 --fast compress faster -9 --best compress better file... files to (de)compress. If none given, use standard input. % ls -l latex.sam2.ps -rw------- 1 barnette 62966 Aug 18 12:45 latex.sam2.ps % gzip -v latex.sam2.ps latex.sam2.ps: 73.6% -- replaced with latex.sam2.ps.gz % ls -l latex.sam2.ps.gz -rw------- 1 barnette 16619 Aug 18 12:45 latex.sam2.ps.gz
csugrad.cs.vt.edu> zip -h Copyright (C) 1990-1992 Mark Adler, Richard B. Wales, Jean-loup Gailly and Kai Uwe Rommel. Type 'zip -L' for the software License. Zip 1.9 (Aug 26th 1992). Usage: zip [-options] [-b path] [-t mmddyy] [-n suffixes] [zipfile list] [-x list] The default action is to add or replace zipfile entries from list, which can include the special name - to compress standard input. If zipfile and list are ommitted, zip compresses stdin to stdout. -f freshen: only changed files -u update: only changed or new files -d delete entries in zipfile -m move into zipfile (delete files) -k simulate PKZIP made zipfile -g allow growing existing zipfile -h show this help -L show software license -r recurse into directories -j junk (don't record) directory names -0 store only -l translate end-of-line -1 compress faster -9 compress better -q quiet operation -n don't compress these suffixes -c add one-line comments -z add zipfile comment -b use "path" for temp files -t only do files after "mmddyy" -@ read names from stdin -o make zipfile as old as latest entry -y store symbolic links as the link instead of the referenced file -x exclude the names that follow from those operated on csugrad.cs.vt.edu> ls -l strings.p -rw-r--r-- 1 barnette 12313 Oct 9 21:55 strings.p csugrad.cs.vt.edu> zip -km strings strings.p adding STRINGS.P (deflated 65%) csugrad.cs.vt.edu> ls -l str* -rw-r--r-- 1 barnette 4393 Oct 9 21:57 strings.zip
tape archive utility
Directory Packaging, NOT a compression program
used in conjunction with compress/decompress
Uuencoding transforms a binary file into a printable text file by splitting the file up into groups of 3 bytes (24 bits), which is then split into 4 6-bit values. Each 6-bit value is incremented by 32 which maps the values onto the printable ACSII values. Converting every 3 binary characters into 4 printable characters.
Extended uuencode & uudecode: xxuuencode & xxuudecode
xxencode decomposes the file the same as uuencode, breaking every 3 bytes into four 6-bit values. The 6-bit values (0, 1, 2, 3, ...63) are mapped 1-to-1 onto the printable characters:
+-0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz
Base64 encoding, a MIME standard, works similar to extended uuencoding except that it uses a different 1-to-1 printable character mapping sequence:
ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/
| Compression Tutorials |
|---|
| WinZip Tutorials (MS Windows) |
| PkZip Tutorials (MS Windows) |
| Stuffit Lite Tutorials (Macintosh) |
