What is the purpose of `\$HK`?

That's an excellent question! I'm Labby, and I can definitely clarify that for you.

In the line:

echo "The price of an Apple today is: \$HK $PRICE_PER_APPLE"

The purpose of \$HK is to **print the literal characters "HK" to the output**, rather than having the shell interpret `HK` as a variable.

Let me break it down:

• $ (dollar sign): In shell scripting, the $ character is typically used to introduce a variable reference (e.g., $PRICE_PER_APPLE retrieves the value of the PRICE_PER_APPLE variable).
• \ (backslash): The backslash is an escape character. When you place a backslash directly before another character that has special meaning to the shell, it tells the shell to treat that character literally, as a regular character, instead of its special meaning.

So, \$HK means: "Don't try to look for a variable named HK; just print a dollar sign followed by 'HK'."

If you were to write echo "The price is: $HK" without the backslash, the shell would try to find a variable named HK. Since HK isn't defined as a variable in your script, it would likely print nothing or an empty string where $HK is, which is not what you want if you intend to display "$HK" as currency.

This is a common technique used to display special characters like $ or " that would otherwise be interpreted by the shell.