The command add-apt-repository is used for adding PPA reference to our Ubuntu or Debian systems. For newer installations, this command may not available in your system. Use following commands to add this command utility in your system as per your operating systems.
Ubuntu & Debian Latest Version
The latest version of Ubuntu 18.04, 16.04, 14.04, Debian 9/8, add-apt-repository command utility is available under the software-properties-common package. So use the following command to install it.
sudo apt-get install software-properties-common
Reading package lists... Done Building dependency tree Reading state information... Done The following packages were automatically installed and are no longer required: gir1.2-goa-1.0 gir1.2-snapd-1 Use 'apt autoremove' to remove them. The following NEW packages will be installed: software-properties-common 0 upgraded, 1 newly installed, 0 to remove and 4 not upgraded. Need to get 0 B/9,912 B of archives. After this operation, 197 kB of additional disk space will be used. Selecting previously unselected package software-properties-common. (Reading database ... 186717 files and directories currently installed.) Preparing to unpack .../software-properties-common_0.96.24.32.3_all.deb ... Unpacking software-properties-common (0.96.24.32.3) ... Processing triggers for man-db (2.8.3-2) ... Processing triggers for dbus (1.12.2-1ubuntu1) ... Setting up software-properties-common (0.96.24.32.3) ...
Ubuntu 13.10/Debian 7 and Older Versions
For the Ubuntu 13.10 Systems and Debian 7 (Wheezy) or its earlier versions, add-apt-repository command is available under python-software-properties package. Use the following command to install it.
sudo apt-get install python-software-properties