Archivers/Compressors/Squeezers V1.00

Contents:



INTRODUCTION

Author: Keith Petersen
File: /pub/msdos/starter/00-files.doc
Revised: March 20, 1994

All about ARC, ARJ, LZH, ZIP, ZOO, LBR, Compressed and Squeezed files.

Some of the files in the SimTel Software Repository MS-DOS collections have been transformed by using one of the standard freely-distributable utilities that either SQueezes, LiBRaries, ARChives, ARJs, LZHs, ZIPs, or ZOOs files. Some files in other collections have been compressed.

This transformation is performed to compress the files to minimize download time, and/or combine several related files into a single easily-managed file. You cannot use or run any of these files without first transforming them back to their original state.

These processed files are specially named with a file type that signifies the transformation. These are:

  .arc   for files archived with PKPAK.EXE
  .arj   for files archived with ARJ.EXE
  .lbr   for files libraried with LU.EXE
  .lzh   for files archived with LHA.EXE
  .zip   for files archived with ZIP.EXE
  .zoo   for files archived with ZOO.EXE
  .?q?   for squeezed files (middle letter is a Q).
  .z     for files compressed with gzip (obsolete)
  .gz    for files compressed with gzip
  .Z     for files compressed with compress


ARC FILES

PKPAK is used to create and maintain file archives. An archive is a group of files collected together into one file in such a way that the individual files may be recovered intact. PKPAK will automatically compress member files when adding them to the archive, and PKUNPAK will expand them upon extraction. For files with the .ARC extension, you must have a copy of file /pub/msdos/archiver/pk361.exe to extract the component files. PK361.EXE is a "self-extracting archive." When you run this program, it will produce PKPAK, PKUNPAK and related documentation. After you end up with a copy of PKUNPAK you can use it to extract files. An example of using PKUNPAK to unpack an ARChive "FILE.ARC" is:

"A> pkunpak file"

You do not need to supply the ARC file type when specifying "file."


ARJ FILES

ARJ is used to create and maintain file archives. An archive is a group of files collected together into one file in such a way that the individual files may be recovered intact. ARJ will automatically compress member files when adding them to the archive, and will expand them upon extraction. For files with the .ARJ extension, you must have a copy of file /pub/msdos/archiver/arj241a.exe to extract the component files. ARJ241A.EXE is a "self-extracting archive." When you run this program, it will produce ARJ and related documentation. After you end up with a copy of ARJ you can use it to extract files. An example of using ARJ to unpack a ARJ archive "FILE.ARJ" is:

"A> arj e file"

You do not need to supply the ARJ file type when specifying "file."


LZH FILES

LHA is used to create and maintain file archives. An archive is a group of files collected together into one file in such a way that the individual files may be recovered intact. LHA will automatically compress member files when adding them to the archive, and will expand them upon extraction. For files with the .LZH extension, you must have a copy of file /pub/msdos/archiver/lha213.exe to extract the component files. LHA213.EXE is a "self-extracting archive." When you run this program, it will produce LHA and related documentation. After you end up with a copy of LHA you can use it to extract files. An example of using LHA to unpack an LZH archive "FILE.LZH" is;

"A> lha e file"

You do not need to supply the LZH file type when specifying "file."


ZIP FILES

ZIP is used to create and maintain file archives. An archive is a group of files collected together into one file in such a way that the individual files may be recovered intact. ZIP will automatically compress member files when adding them to the archive, and UNZIP will expand them upon extraction. For files with the .ZIP extension, you must have a copy of file /pub/msdos/zip/unz51x.exe to extract the component files. UNZ51X.EXE is a "self-extracting archive." When you run this program, it will produce UNZIP.EXE and its documentation. After you end up with a copy of UNZIP you can use it to extract files. An example of using UNZIP to unpack an archive "FILE.ZIP" is:

"A> unzip file"

You do not need to supply the ZIP file type when specifying "file."

The companion program to create ZIP files is /pub/msdos/zip/zip20x.zip. Also available: /pub/msdos/zip/pkz204g.exe - PKWare's fast ZIP and UNZIP programs (a self-extracting archive).


ZOO FILES

ZOO.EXE is an archiving program that is similar to PKPAK and ZIP, but it is not compatible with either. ZOO can produce archives with long pathnames in them (directory names as well as the file name) and it can store comments about each file. If you want to take apart a ZOO archive, you will need a copy of ZOO.EXE. The current version of ZOO is zoo210.exe, which may be found in the /pub/msdos/zoo directory. The zoo syntax for file extraction is:

"A> zoo e file"

You do not need to supply the ZOO file type when specifying "file."


LBR FILES

LU and its relatives (LUP, LUU, LUE, LUT, LU86, LAR etc.), maintain libraries of files. Most LU-type programs do not perform any compression. Because of this, most people will squeeze files before adding them to a library if they want to save space. If you want to remove the component files from an .LBR file, you should have a copy of file /pub/msdos/starter/lue220.com. This will break up the library into its component parts, and optionally unsqueeze any .?Q? files at the same time. The syntax for LUE would be:

"A> lue220 file"

where file was really FILE.LBR. LUU.COM can be used to create a .LBR file.


SQUEEZED FILES

NUSQ.COM is used to unsqueeze, or expand files that have a "Q" as the middle letter of the file type. Such files have been squeezed, or compressed with SQPC.COM or something similar. These programs use Huffman Encoding to reduce the size of the target file. Depending on the distribution of data in a file it can be reduced in size by 5% to 60% by squeezing it. If you download a file with a file type indicating that it is squeezed, you will need file /pub/msdos/starter/nusq110.com to expand it before you can use it. The syntax to unsqueeze a file would be:

"A> nusq110 file.tqt"

where file.tqt was the file you wanted to unsqueeze. You must supply the full file name and type.


COMPRESSED FILES

COMP430D is used to uncompress, or expand files that have a ".Z" file type. Such files have been compressed with a Unix-compatible compress program which uses LZW encoding to reduce the size of the target file. Depending on the distribution of data in a file it can be reduced in size by 25% to 70% by compressing it. If you download a file with a file type indicating that it is compressed, you will need file COMP430D.EXE from /pub/msdos/compress/comp430d.zip to expand it before you can use it. The syntax to uncompress a file would be:

"A> comp430d -d file.Z"

where file.Z was the file you wanted to uncompress. You must supply the full file name and type.


GZIP COMPRESSED FILES

GZIP is used to uncompress, or expand files that have a ".gz" file type. Such files have been compressed with a compress program which uses the same encoding as ZIP to reduce the size of the target file. Depending on the distribution of data in a file it can be reduced in size by 35% to 80% by compressing it with GZIP. You will need file GZIP.EXE from /pub/msdos/compress/gzip124.zip to expand it before you can use it. The syntax to uncompress a file would be:

"A> gzip -d file.gz"

where file.gz was the file you wanted to uncompress. You must supply the full file name and type.


MORE INFORMATION

For more information on ARChives, see the documentation for PKPAK/PKUNPAK which is included in the PK361.EXE file. For more information on ARJ archives, see the documentation for ARJ which is included in the ARJ241.EXE file. For more information on LZH archives, see the documentation for LHA which is included in the LHA213.EXE file. For more information on ZIP archives, see the documentation for UNZIP/ZIP which is included in the UNZ51X.EXE and ZIP20X.ZIP files. For ZOO archives, see the documentation included in ZOO210.EXE and UGUIDE.ZIP. The doc files included with the various LU utilities will explain .LBR's, and LUDEF5.DOC explains the layout of these files in detail.


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