University of Virginia Department of
    Computer Science


Multi-purpose Internet Mail Extensions allow the transmission of files, images, audio, video and other formats using standard internet mail. This frees users from having to encode all their non-textual information into seven-bit ASCII. (When files are "attached" to mail, this is the method that is used.)

One nice feature of Netscape 2.0 is automatic decoding. If you attach an HTML document, graphic file, etc. to mail or news it is automatically displayed below the body of the message. Pine allows you to save attached messages easily, while elm takes a little more coercion.


UUencoding is the conversion of binary data (typically picture, sound, and postscript files) into seven-bit ASCII for transmission within normal electronic mail messages.

A typical encoding command is uuencode file1 file2 >> outfile.uu. Likewise, uudecode file.uu will extract the information. A somewhat more robust decoder is UUDEVIEW.


The UNIX Tape Archive format is used to combine multiple files in many directories into one large convenient file for electronic transfer. Since it was not originally designed for hard disk systems, there are some options that are always necessary:

Use tar xvf file.tar to detar a file (x for extract, v for verbose, f for file). Likewise, tar cf tarfile.tar directory will put all the files in a particular directory into tarfile.tar.


Like its PC counterpart PKZIP, Gzip quickly archives and compresses files for transfer. Other formats besides the popular .gz and .Z of Gzip and .zip of PKZIP are ARC,LHZ and ZOO.


A PC favorite, PKZIP and its related programs allow fast, easy compression and archival of files. Another useful application is Winzip, a powerful Windows-based decompression tool that supports many formats. It also has many useful options, such as "tryout" which allows you to undo changes to the Windows .ini files. The new version for Windows 95 also supports long filenames and works integrally with Microsoft Explorer.

Graphics and Video

Most compression schemes for graphics and video are "lossy", which means that some information is lost during encoding. In order to view XBM, GIF, JPG and the multitude of other graphics formats, a good viewer such as XV is needed. XANIM is a movie player that supports many different movie formats as well as sound. Both it and XV are in /usr/cs/contrib/bin as "xanim" and "xv.310" respectively.

HelpNet was created by the 1995 incoming graduate class. It is only occasionally updated.
Department of Computer Science
School of Engineering, University of Virginia
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Charlottesville, Virginia 22904-4740

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