I intend to download and install something, but the first pre-requisite says:

You need software-properties-common installed in order to add PPA repositories. If not installed(...)

and then it shows instructions how to install it.

I haven't used my PC in a long time, so I don't know if I installed it before or not. How can I check that out?

2 Answers 2


You can query with apt, for example

apt policy software-properties-common


apt list --installed software-properties*

or with dpkg

dpkg -l software-properties-common

However it won't do any harm to follow the installation instructions - you would just get a message like

software-properties-common is already the newest version (

if it is already installed.


The software-properties-common package provides the add-apt-repository command.

So in this case, just try to run the add-apt-repository command they want you to run. If it works, everything is fine. Otherwise you will get a "Command not found" error message which should probably even advise you on which package to install to get it:

sudo apt install software-properties-common

However, you could also run this command safely if the package is already installed. It will detect this and not reinstall it again.

Other, general ways to find out whether a specific package is installed are described in @steeldriver's answer to this question.

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