Providing parameter defaults
Within bash parameters, there are named spaces in the memory that allow us access to stored values. There are two types of parameters:
Variables
Special parameters
Special parameters are read-only and are pre-set by the shell. Variables are maintained by ourselves as well as bash. In general, when talking about syntax, bash will refer to variables by their family name of parameters.
Variables
Variables are one type of parameter. These can be set by the system or by ourselves. For example, $USER is a variable parameter that is set by the system but can be written by us. As such, it is not a read-only requisite of special parameters.
Special parameters
Special parameters are the second parameter type and are managed by the shell itself and are presented as read-only. We have come across these before in parameters, such as $0 but let's take a look at another $-. We can expand these parameters to gain an understanding of their use, using the echo command:
$ echo "My shell...
