[Ubuntu] add-apt-repository not found

The following extra packages will be installed:
python-pycurl python3-pycurl python3-software-properties unattended-upgrades
Suggested packages:
libcurl4-gnutls-dev python-pycurl-dbg python3-pycurl-dbg bsd-mailx
mail-transport-agent
The following NEW packages will be installed:
python-pycurl python-software-properties python3-pycurl
python3-software-properties software-properties-common unattended-upgrades