Together with the question you are linking, there is another related question in Unix & Linux: Are there naming conventions for variables in shell scripts?.
There you can find a couple of good answers:
Variables that are introduced by the operating system or start up
scripts etc. are usually all in CAPITALS
, these are called
'envrironment variables'.
To prevent your own variables from conflicting with environment
variables, it is a good practice to use lower case
.
Together with a Shell Style Guide link, where you can find:
Naming Conventions
Function Names
▶ Lower-case, with underscores to separate words. Separate libraries
with ::. Parentheses are required after the function name. The keyword
function is optional, but must be used consistently throughout a
project.
Variable Names
▶ As for function names.
Constants and Environment Variable Names
▶ All caps, separated with underscores, declared at the top of the
file.
There is no suggested convention in man bash
, just note the "be careful with uppercase" warning.