Install MySQL on Ubuntu Natty without password prompt and using shell variable as password

Question

I'm trying to install MySQL on Ubuntu Natty from a shell script. However, I keep running into one major issue: when I try to define the password outside of the shell script.

Below is the code to my shell script (which I have saved in /etc/init.d/install_mysql:

export DEBIAN_FRONTEND=noninteractive
echo mysql-server-5.1 mysql-server/root_password password $dbpass | debconf-set-selections
echo mysql-server-5.1 mysql-server/root_password_again password $dbpass | debconf-set-selections
apt-get -y install mysql-server

So what I enter in the terminal is:

dbpass="mysqlpass"
chmod +x /etc/init.d/install_mysql
/etc/init.d/install_mysql

MySQL installs, but it installs without a password, so I can just do something like mysql -uroot to access mysql (which I don't want).

The funny thing is if I put the password in the shell script as regular text, it works ok. So if I my install script is as follows, everything works (i.e. I must specify a password to access mysql):

export DEBIAN_FRONTEND=noninteractive
echo mysql-server-5.1 mysql-server/root_password password mysqlpass | debconf-set-selections
echo mysql-server-5.1 mysql-server/root_password_again password mysqlpass | debconf-set-selections
apt-get -y install mysql-server

Is there a way I can use a shell script variable to define my password in the shell script, instead of entering the password literally?!

Thanks in advance.

EDIT:

I just edited the variable declaration $dbpass="mysqlpass" to dbpass="mysqlpass". It was a typo.

Answer 1

$dbpass="mysqlpass"

Yeah, this is several types of wrong. Variable names don't start with $, and variables won't be passed to the environment of subprocesses unless exported.

dbpass="mysqlpass"
export dbpass

Note that environment variables are not considered a secure mechanism for sharing data; you may want to retool your script to read the password from stdin instead, which would be a bit more secure.

Answer 2

$dbpass="mysqlpass"

should be

dbpass="mysqlpass"

As you've written it, $dbpass will be evaluated, and isn't defined, so comes out as an empty variable, boiling down to

="mysqlpass"

---

well, since it was a typo, then here's the answer:

MySQL looks for the envvar MYSQL_PWD: http://dev.mysql.com/doc/refman/5.0/en/environment-variables.html