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I'm trying to write a configuration script for new servers, and one of the first steps is to install a series of required packages, such as MySQL, phpMyAdmin, etc. using apt-get install However, when dpkg tries to configure them it asks you for a few options, such as MySQL root password, phpMyAdmin passwords, what server to use, etc.

Since I will likely be passing this script on to co-workers who are unlikely to read the prompts, and my desire to simply start it and walk away, I'd like to know how to pass in a series of "default" answers/values for it to use. This might include usernames/passwords/other dynamic values passed on command line.

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I realize that having passwords in a script is a security issue, but I'm willing to ignore it, particularly in the more general sense of installing packages that an answer to this would imply.

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2 Answers 2

up vote 19 down vote accepted

Use debconf's configuration preseeding.

Do a test install to get the values that you want:

root@test1:~# apt-get install mysql-server

..and set the root password when prompted during the install.

Then you can check what the debconf settings look like for what you just installed:

root@test1:~# debconf-get-selections | grep mysql-server
mysql-server-5.5        mysql-server/root_password_again        password
mysql-server-5.5        mysql-server/root_password      password
mysql-server-5.5        mysql-server/error_setting_password     error
mysql-server-5.5        mysql-server-5.5/postrm_remove_databases        boolean false
mysql-server-5.5        mysql-server-5.5/start_on_boot  boolean true
mysql-server-5.5        mysql-server-5.5/nis_warning    note
mysql-server-5.5        mysql-server-5.5/really_downgrade       boolean false
mysql-server-5.5        mysql-server/password_mismatch  error
mysql-server-5.5        mysql-server/no_upgrade_when_using_ndb  error

There's some noise there, but the important part is the password settings.

Then, for a fresh install, you can avoid the prompts completely by setting the password beforehand:

root@test2:~# echo "mysql-server-5.5 mysql-server/root_password_again password Som3Passw0rd" | debconf-set-selections
root@test2:~# echo "mysql-server-5.5 mysql-server/root_password password Som3Passw0rd" | debconf-set-selections
root@test2:~# apt-get install mysql-server

No prompts at all during that install.

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4  
sudo apt-get install debconf-utils as necessary. –  Andrew Jul 13 '12 at 5:45
    
This looks like exactly what I was looking for, thanks! I'll give it a try shortly. –  Slokun Jul 13 '12 at 18:26
    
Aside from a known error with phpMyAdmin not accepting a pre-seeded MySQL root password, this works perfectly! –  Slokun Jul 13 '12 at 20:21
    
just wondering, is there a way to get possible debconf settings from the package system without installing the packages? –  stefan.at.wpf Sep 2 '12 at 21:05
export DEBIAN_FRONTEND=noninteractive
apt-get -q -y install _packages_
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Do you have a reference for what's reading $DEBIAN_FRONTEND? –  Andrew Jul 13 '12 at 3:50
    
This has been a part of Debian for so long that I think only Ian could really tell you when it was added. –  Michael Hampton Jul 13 '12 at 4:13
    
@Andrew It's read by debconf, which is what actually deals with the questions. –  mgorven Jul 13 '12 at 4:50
    
@mgorven Ahh, I've not gone much deeper than dpkg before. –  Andrew Jul 13 '12 at 5:43

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