Suntar is the simplest and cheapest way to communicate
data between a Macintosh and a UNIX machine, provided you
have a physical medium which may be connected to both
machines (usually a 720 or 1440K disk, but also tape
units or removable disks). It reads and writes disks in
the UNIX tar format, automatically converting plain text
files and the MacBinary and BinHex 4.0 formats, used in
public domain archives to store Macintosh files in UNIX
files. It's also a powerful file format converter.