7.4 Odd Letters -- Decoding File Endings
Big Dummy's Guide to the Internet

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      There are a wide variety of compression methods in use.  You can
tell which method was used by the last one to three letters at the end of
a file. Here are some of the more common ones and what you'll need to un-
compress the files they create (most of these decompression programs can
be located through archie).

.txt or .TXT  By itself, this means the file is a document, rather than a
              program.

.ps or .PS    A PostScript document (in Adobe's page description
              language).  You can print this file on any PostScript
              capable printer, or use a previewer, like GNU project's
              GhostScript.

.doc or .DOC  Another common "extension" for documents.  No decompression
              is needed, unless it is followed by:

.Z            This indicates a Unix compression method. To uncompress,
              type

                   uncompress filename.Z

              and hit enter at your host system's command line. If the
              file is a compressed text file, you can read it online by
              instead typing

                   zcat filename.txt.Z |more

              u16.zip is an MS-DOS program that will let you download
              such a file and uncompress it on your own computer. The
              Macintosh equivalent program is called MacCompress (use
              archie to find these).

.zip or .ZIP  These indicate the file has been compressed with a common
              MS-DOS compression program, known as PKZIP (use archie to
              find PKZIP204.EXE).  Many Unix systems will let you un-ZIP
              a file with a program called, well, unzip.

.gz           A Unix version of ZIP.  To uncompress, type

                   gunzip filename.gz

              at your host system's command line.

.zoo or .ZOO  A Unix and MS-DOS compression format.  Use a program called
              zoo to uncompress

.Hqx or .hqx  Mactintosh compression format. Requires the BinHex program.

.shar or      Another Unix format. Use unshar to uncompress.
.Shar

.tar          Another Unix format, often used to compress several related
              files into one large file. Most Unix systems will have a
              program called tar for "un-tarring" such files.  Often, a
              "tarred" file will also be compressed with the gz method,
              so you first have to use uncompress and then tar.

.sit or .Sit  A Mactinosh format that requires the StuffIt program.

.ARC          Another MS-DOS format, which requires the use of the ARC
              or ARCE programs.

.LHZ          Another MS-DOS format; requires the use of LHARC.

     A few last words of caution: Check the size of a file before you get
it. The Net moves data at phenomenal rates of speed.  But that 500,000-
byte file that gets transferred to your host system in a few seconds
could take more than an hour or two to download to your computer if
you're using a 2400-baud modem.  Your host system may also have limits on
the amount of bytes you can store online at any one time.  Also, although
it is really extremely unlikely you will ever get a file infected with a
virus, if you plan to do much downloading over the Net, you'd be wise to
invest in a good anti-viral program, just in case.