Using variables in Reader and Writer configuration?

You can also specify mask.

Is this the correct way?

Is there something else I need to do?

Sorry I do not understand the question
The original question was about dynamic sources.
So we assumed that you want to use a variable inside the file name
So you can load data from different files depending on variable value

Something like this will help a lot

My data looks like this
Screeshot
I want to load only that data not this one.
Screeshot

Or
My directory looks like that
Screeshot
I want to load data only from files which look like that

Or here is my excel file
attachment
Here is how I want to transform it
attachment

I woud like to see the names of the source files in the linked SQL Database tables. So I know where the data comes from.
Is there a possibility to get those names in SQL database tables.

So you have one table which holds all the data and you want to have a field populated with the file name?