I'm a noob in both Docker and Linux and studying a Dockerfile from a shared project I work on. Something I don't understand-- at the top of the Dockerfile we have:

# Never prompts the user for choices on installation/configuration of packages
ENV DEBIAN_FRONTEND=noninteractive

But then in a whole series of later Docker RUN commands, I see that -yqq is appended to all the apt-get commands: apt-get {install,update,upgrade} -yqq .... Since -yqq is supposed to automatically answer questions for apt-get and make it silent, I'm confused as to whether it's redundant. But I'm having a hard time finding straightforward answers, so here are some questions:

  • Does apt-get directly read the value of DEBIAN_FRONTEND and set options accordingly?
  • Are -y and -qq redundant for one or more of apt-get {install,update,upgrade} if DEBIAN_FRONTEND=noninteractive is set?

1 Answer 1


DEBIAN_FRONTEND is read by debconf, which is used to prompt for input in many packages’ maintainer scripts. apt does not take this environment variable into account, so DEBIAN_FRONTEND=noninteractive is not redundant with apt’s -y and -q options.

Various other tools can be involved in package installations; see for example Force non-interactive "dpkg --configure" when using apt-get install.

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