Returning an error value
Even though human-readable error messages are important, we must not forget to return a value to the shell that indicates an error. We have already seen that returning 0 means that everything is okay, while returning something else (most of the time, 1) means that some kind of error did occur. However, we can return more specific values if we want so that other programs relying on our program can read those numbers. For example, we can actually return the
errno variable since it is just an integer. All the macros we have seen, such as
ENOENT, are integers (13 and 2 for
In this recipe, we will learn how to return the
errno numbers to the shell to provide more specific information.
The same set of programs mentioned in the previous recipe apply to this recipe.
How to do it…
In this recipe, we will make the seventh version of our
simple-touch program. Let's get started: