You will most often use Bash functions to make your shell life easier; instead of typing out complex command pipelines, create a function and inject arguments. You'd place these in your bashrc file, ...

At a basic level, parameter expansion means changing Bash syntax into a value—expanding it. For example: echo "$foo" This ...

There are quite a few exit codes used on Linux systems, though no listing you can display when you’re feeling curious. In fact, you won’t see the numeric codes unless you specifically ask for them.