Use executable calling syntax from external file

[crowndip]

Is your feature request related to a problem? Please describe.
My multifunction printer defaults to the automatic document feeder. I want it to scan from flatbed.
i can use option "--source flatbed" when calling the scanning program

Describe the solution you'd like
Crete a scanner.conf where the content would be:
sudo scanimage --mode {$this->modes[$mode]} --resolution {$resolution} -x 215 -y 297| pnmtojpeg > /tmp/img

User could then modify the command, like add "--source flatbed" for example
ScannerStorage.php would pull the line from this file to call the scanning program

Describe alternatives you've considered
Users could modify the ScannerStorage.php manually but then it reverts with each app apdate

Additional context