.mh "Foreword" .fo ""- [rn [pn]] -"" The Software Tools Subsystem is a set of program development tools based on the book .ul Software Tools .sb by Brian W. Kernighan and P. J. .xb Plauger. It was originally developed for use on the Prime 400 computer in 1977 and 1978 in the form of several cooperating user programs. [cc]mc | The present Subsystem, the ninth version, is a powerful tool that [cc]mc aids in the effective use of computing resources. .pp The command interpreter, also referred to as the "shell," is a vital part of the Subsystem. It is a program which accepts commands typed by the user on his terminal and converts them into more primitive directions to the computer itself. The user's instructions are expressed in a special medium called the "command language." The greatest part of this document is involved with describing the command language and giving examples of how it is used. .pp Three areas will be covered in the following pages. First, there is a tutorial on the use of the command language. New Subsystem users should read this chapter first. Some minimal knowledge of terminal usage is assumed; if you are unsure of yourself in this area, see Prime's published documentation and the .ul Software Tools Subsystem Tutorial for help. Second, there is a summary of the syntax and semantics of the command language. Experienced users should find this chapter valuable as a reference. Finally, there is a selection of application notes. This chapter is a good source of useful techniques and samples of advanced usage. Experienced users and curious beginners should find it well worthwhile.