When I search for software in the Ubuntu Software Center, how do I know whether or not software is trustworthy to download?
On Windows, I came to be careful about downloading just anything because it might be packaged with adware, or possibly even malicious code.
For example, I found the Metadata Anonymization Tool (website here) in the software centre.
All of the software on the Ubuntu Software Center is safe and is maintained / verified, reviewed / developed by known developers (either from Debian or Ubuntu) and that's the reason it is in the Ubuntu repositories.
More risky business is when installing applications from third-party sources which is done by adding the Personal Package Archive (PPA) to your system. After a PPA is added it is trusted by the system and any updated software from that PPA will be updated automatically. Well, if some developer goes rogue and makes a malicious software then that application will come in as an update, if the particular PPA was added. Hence, adding PPAs should be done cautiously.
Read more in the following excellent links.
Case where the user compiles and installs using make/cmake
Generally some libraries, custom compilers and customized applications which are system build and parameter dependent (need configure) are installed that way. Hence, usually these softwares come from known developers, researchers, scientists, companies, GNU developers, etc...
However, exercise caution and use your experience while building softwares from source. Don't just blindly build any piece of code !
I normally presume that all downloads through Ubuntu Software Center is safe. You can use the reviews to check the user feedback of these software.
Also, if you are using external PPA, there is a risk that you are open the doors to unsafe script. Use only the PPAs you trust.
