unix utilities

A utility in Unix is considered to be a standard application program which is included with most Unix systems. Unix contains many utilities; technically speaking almost all commands could be considered utilities. Therefore anyone who has ever logged onto a Unix system has used one of its utilities in some way or another. Some utilities are very simple operations while others are complex programs which contain their own sets of commands. While not true of all utilities, the majority of Unix utilities fall into one of three categories: editors, filters, and communication programs.
Editors are used for creating and modifying text files. Ed, Ex, Vi, and Emacs are the standard Unix editors. Many systems may also have other popular word processors such as WordPerfect and Word. Ed and Ex are called line editors because they display and edit only one line at a time, while Vi and Emacs are considered full-screen editors. All the standar...