You downloaded Ubuntu (open source software operating system) and now want to verify that the image you have is authentic and not tampered with.
Here’s how you can do that:
Open terminal (CTRL-ALT-T) and go to the folder where you have the Ubuntu file
Here’s the command to verify your file:
echo "xxxxxxxxxx" | shasum -a 256 --check
Make sure you replace xxxxxxxxxx with the version you downloaded
echo “add4614b6fe3bb8e7dddcaab0ea97c476fbd4ffe288f2a4912cb06f1a47dcfa0 *ubuntu-18.04.3-desktop-amd64.iso” | shasum -a 256 --check
If it shows OK you are all set and proceed to use it with confidence. Enjoy!