Linux and Unix Shell Programming

Chapter 22. Creating screen input

Screen input or data input is the ability to take input (from the keyboard in our case) then validate the input. If it’s OK accept it, if not throw it back out.

We have seen functions that test for certain conditions; for example the length of a string; whether a string is either numeric or character based. We will be using these functions amongst others in this chapter.

In this chapter we will cover:

• validating input;

• adding, deleting, amending and viewing records; and

• working file update scripts.

This chapter may be a bit heavy going at the first read, so you may want to scan it first, then come back later. Validation can be fairly code-intensive, but to catch all possible errors, the code has to test for at ...