RUN sed 's/main$/main universe/' -i /etc/apt/sources.list
---> Running in b50528f9dcde
sed: /etc/apt/sources.list: No such file or directory
The command '/bin/sh -c sed 's/main$/main universe/' -i /etc/apt/sources.list' returned a non-zero code: 1
Step 14/29 : RUN sed 's/main$/main universe/' -i /etc/apt/sources.list
---> Running in b50528f9dcde
Why is there no such /etc/at/sources.list? Is it to be manually made, what does it refer to? I do not even know this..!