"Dpkg: check that unix package is installed. Bash script: install package if not present" via https://www.thinkplexx.com/learn/howto/linux/packaging/dpkg-check-that-unix-package-is-installed-example-install-package-if-not-present

dpkg-install-package-if-not-present.txt

Dpkg: check that unix package is installed. Bash script: install package if not present
By neokrates, written on May 21, 2010	

Was the package already installed or it still needs to be?

Software:

✔ Ubuntu *

dpkg -s can be used.

# Example: is libasound installed?
dpkg -s libasound2|grep installed

# Here is some logic in bash script, like installing package if it is not there:
problem=$(dpkg -s xulrunner-1.9|grep installed)
echo Checking for libxul: $problem
if [ "" == "$problem" ]; then
     echo "No libxul. Setting up libxul"
     sudo apt-get --force-yes --yes install xulrunner-1.9
fi