Disable pop-ups for an unattended/non-interactive apt-get install in Ubuntu/Debian

So, here I was writing a script that would automate the installation of a package in Ubuntu 14.04 and all was going swimmingly. Until I ran it. You know how some apt-get installs sometimes involve a technicolor pop-up that asks you for stuff? Well, those pop-ups interrupted my script which didn't proceed further. After much digging, I found that there are a couple of solutions for this:

1. One trick is to set a flag that disables the interactive pop-ups. This can be done like so:

   $ export DEBIAN_FRONTEND=noninteractive
   $ aptitude -y install foopackage
   $ aptitude -y install barpackage
   $ unset DEBIAN_FRONTEND

   IOW, set the flag, perform the install, disable the flag. Disabling the flag can also be done by running dpkg-reconfigure debconf.

   An alternative (and something of a shortcut) is to simply use (all in one line):
   DEBIAN_FRONTEND=noninteractive aptitude -y install foopackage

   Rather nifty :)

2. The other option is relatively more involved and is useful when you want to populate fields rather than accept the defaults.

   $ echo "foo-server foo-server/root_password password ABCDE" | debconf-set-selections
   $ echo "foo-server foo-server/root_password_again password ABCDE" | debconf-set-selections
   $ apt-get -y install foo-server

   The above is what is used to run through the prompts during a typical MySQL installation. IOW, foo=mysql. To get the list of variables for other packages, you will need to install debconf-utils and then run the appropriately named debconf-get-selection foo-server to get details about the structure of the foo-server package.

(BTW, the -y switch in the apt-get and aptitude statements is short for "assume yes for everything" and ensures that we accept the default choice when apt throws up any prompts.)

Hope this helps!