How can I automate dpkg/apt-get?

Question

I\'m trying to create a script that automatically downloads packages for new servers. However, some things like \'mysql-server\' can not installed automatically cause you ne

Answer 1

Any Debian package which uses debconf to get configuration values can be run unattended. The trick is that debconf will first search for pre-installed answers to any config question which a given package has.

Pre-install config answers

Just create a file in the following format,

# Use one line for each question
package-name question-name question-type answer
package-name question-name question-type really long \
answer here
package-name question-name question-type answer
...

and feed it into the system like so:

$ debconf-set-selections my-selections-file

Now, you're ready to apt-get install, as usual.

One-off

Since this command also reads from stdin, you can do:

$ echo "man-db man-db/auto-update boolean true" | debconf-set-selections

Finding default answers

How do you know which packages use these configuration answers? Well, if you've already installed the package in question interactively, you can query your local system to see what values are currently configured. debconf-get-selections prints a list of all config answers for the current system. For example

$ debconf-get-selections | grep '^man'

returns the following on my system:

man-db  man-db/install-setuid   boolean false
man-db  man-db/auto-update      boolean true

You may need to install the debconf-utils package to make this command available.

Sample

# Preset values to questions which would otherwise be asked while
# installing packages.
# Use debconf-set-selections to install
openssh-server  openssh-server/permit-root-login        boolean false
man-db  man-db/install-setuid   boolean false
man-db  man-db/auto-update      boolean true

Sources

• Anthony Towns' answer & bit-rotting link
• Man debconf-set-selections(1)
• Duplicate answer on ServerFault