Including not only $HOME, $PWD etc but any other you have defined.
Let's say in bash I have several variables: POD3_1, POD3_A, POD3_2, POD3_B, etc. Each of the variables names begins with "POD3".
I'm writing a macro where if the defined variables have a certain prefix some line was to be written. To achieve this how do I loop through a list of defined variables and check their prefixes?
Ex: m4 -Da=1 -Db=2 -Dhud-a=123 -Dhud-b=1452 file.macro
Here the variables that start with 'hud' need to be processed differently.