These commands are for package install on RaspberryPi OS image.
If you have piaware SD card image, the changes you made in files /etc/default/dump1090-fa and /etc/default/dump978-fa will evaporate when you reboot the Pi
The commands for Piaware SD card image are as follows:
NOTE:
If you are not sure which image you have you have, just check the command prompt in PuTTY terminal
If it is a piaware SD card image, the command prompt is:
pi@piaware:~ $
If it is Raspbian image with package install of piaware & dump1090-fa, the command prompt is:
pi@raspberrypi:~ $