I am checking whether a particular apache module is installed using apache2ctl -M. When listing the modules, apache runs a syntax check on the configuration files which prints out "Syntax OK" if everything is fine.

However, this message doesn't seem to be coming from STDOUT or STDERR as it shows even if all output is redirected to /dev/null. i.e.

$ sudo apache2ctl -M
Loaded Modules:
 core_module (static)
 log_config_module (static)
 ...
Syntax OK

$ sudo apache2ctl -M >/dev/null
Syntax OK

How is this being outputted, and is it possible to hide?