What does the dollar sign mean in the sitecore configuration file

Question

I have a parameter in my Sitecore configuration file as shown below. What is the dollar sign used for?

<setting name="MediaFolder" value="$(mediaFolder)"/>

Answer 1

This means that a variable with this name is used, for example:

<sc.variable name="mediaFolder" value="/upload" />

At the beginning of the Sitecore.config file, you can find several variables:

<sc.variable name="dataFolder" value="/data" />
<sc.variable name="mediaFolder" value="/upload" />
<sc.variable name="tempFolder" value="/temp" />

You can use them later in configuration files as follows:

<DumpFile>$(dataFolder)/diagnostics/counters.{date}.{time}.{processid}.txt</DumpFile>

<setting name="MediaFolder" value="$(mediaFolder)" />

Answer 2

$ means the value ...

<setting name="MediaFolder" value="$(mediaFolder)" />

here $ (mediaFolder): value of the mediaFolder variable.

A variable can be defined:

<sc.variable name="mediaFolder" value="/data" />