C++ System Programming Cookbook

How it works...

In step 1, the cp command failed, as file and file2 don't exist. By querying echo $?, we get the error code; in this case, it is 1. This is particularly useful when writing bash scripts where we might need to check for a particular condition.

In step 2, the script just lists the does_not_exist.txt file and reads the error code returned. If all goes fine, it prints an acknowledgment message and returns 0. Otherwise, it returns the error code 11.

By running the script, we get the output as follows:

Here, we notice a couple of things:

• We logged our error string.
• The error code is the one we had set in the script.

Under the hood, ...