$$ is an internal variable, it stores the process ID of the script itself or the current bash instance.
Here is an example use case
<pre class="wp-block-code">```
echo $$
The output prompted.
```
darryl@Darryl-PC$ echo $$
8
```
```
$$ is an internal variable, it stores the process ID of the script itself or the current bash instance.
Here is an example use case
<pre class="wp-block-code">```
echo $$
The output prompted.
```
darryl@Darryl-PC$ echo $$
8
```
```