How to use sudo inside a docker container?

Question

Normally, docker containers are run using the user root. I\'d like to use a different user, which is no problem using docker\'s USER directive. But this use

Answer 1

if you want to connect to container and install something
using apt-get
first as above answer from our brother "Tomáš Záluský"

docker exec -u root -t -i container_id /bin/bash

then try to

RUN apt-get update or apt-get 'anything you want'

it worked with me hope it's useful for all