Which user owns the installed plugins?

If you run ./configure --with-user=nagios, then at make install time, the installation will set the ownership of the plugins to the nagios user (similarly for --with-group). If these options are not set, the plugins will be installed with the install user's owner and group permissions - it is your responsibility to set other permissions, if required.

The only exception are root plugins. These are under plugins-root/ and are also installed with the install user's owner and group permissions.

If you run:

$ make install-root

This will set permissions to root, assuming you are either root or using fakeroot. If not, the setuid bit is still set, but the plugin may not work correctly. This is the behaviour used by coreutils for the su binary and is duplicated in this project.