cabextract (http://www.kyz.uklinux.net/cabextract.php) is Free Software for unpacking cabinet files in UNIX
libmspack (http://www.kyz.uklinux.net/libmspack/) is an LGPL licensed, portable library for creating and extracting CAB files and other Microsoft formats.
Computer files are so called because they are the computer equivalent of card, paper, or microfiche files in the traditional office environment.
As far as the operating system is concerned, a file is in most cases simply a one-dimensional stream of bytes (whole numbers in the range of 0 to 255), which is treated by the operating system as a single logical unit.
The content of the document file is arranged in a way that the word-processing program understands, but the user chooses the name and location of the file, and she provides the bulk of the information (such as words and text) that will be stored in the file.