Installing software from different resources than the Apple AppStore usually causes a warning similar to the following:

(..) cannot be opened because the developer cannot be verified (…)

Using the Finder, this is easy to fix: right-click and open. The following dialog provides a warning but also contains a button to open it nonetheless.

However, sometimes we need to do this from within a shell, e.g. because we installed the tool (which is a commandline tool) using a shell.

The problem is that macOS puts the application or the executable into quarantine. This can be easily fixed with

xattr -d com.apple.quarantine $EXECUTABLE

Please note: This may be related to the Gatekeeper but i do not want to disable it completely (sudo spctl --master-disable) and adding the executable with spctl --add $EXECUTABLE did not work either: Maybe this only works for application bundles.