Comment # 1 on bug 1043532 from Larry Finger

I agree that "test -r $config" in /bin/sh is funky. It is true whether symbol
config is defined or not. Your form of the if test does return true/false
correctly.

A bigger question is why your system gets there. Nothing ever sets or exports
symbol 'config', thus this particular if test should always fail.

Please update your system and report what 'sudo systemctl status
vboxadd-service' outputs. On a Leap 42.2 virtual machine, I get

finger@linux-bfk0:~> sudo systemctl status vboxadd-service
root's password:
��� vboxadd-service.service - Start/Stop VirtualBox Guest Linux module
   Loaded: loaded (/etc/init.d/vboxadd-service; enabled; vendor preset:
disabled)
   Active: active (exited) since Fri 2017-06-09 15:28:45 CDT; 30s ago
  Process: 862 ExecStart=/etc/init.d/vboxadd-service start (code=exited,
status=0/SUCCESS)
 Main PID: 862 (code=exited, status=0/SUCCESS)
    Tasks: 8 (limit: 512)
   CGroup: /system.slice/vboxadd-service.service
           ������953 /usr/sbin/VBoxService --pidfile /var/run/vboxadd-service.sh

Jun 09 15:28:45 linux-bfk0 systemd[1]: Started Start/Stop VirtualBox Guest
Linux module.
Jun 09 15:28:45 linux-bfk0 vboxadd-service[862]: vboxadd-service.sh: Starting
VirtualBox Guest Addition service.
Jun 09 15:28:45 linux-bfk0 vboxadd-service.sh[946]: VirtualBox Guest Addition
service started.
finger@linux-bfk0:~>