bash: add-apt-repository: command not found

If you are trying to add a ppa repository and get the following error

bash: add-apt-repository: command not found

You need to install python-software-properties, like so

apt-get install python-software-properties

If you have python-software-properties installed and are still getting this error, there is some problem with the package. Uninstall and reinstall it.

apt-get remove python-software-properties --purge && apt-get install python-software-properties

or

apt-get install --reinstall python-software-properties && sudo dpkg-reconfigure python-software-properties