Removing virtualbox-5.1 (5.1.18-114002~Ubuntu~xenial) ...
Purging configuration files for virtualbox-5.1 (5.1.18-114002~Ubuntu~xenial) ...
dpkg: warning: while removing virtualbox-5.1, directory '/usr/lib/virtualbox' not empty so not removed
Processing triggers for desktop-file-utils (0.22-1ubuntu5.1) ...
Processing triggers for bamfdaemon (0.5.3~bzr0+16.04.20160824-0ubuntu1) ...
Rebuilding /usr/share/applications/bamf-2.index...
Processing triggers for gnome-menus (3.13.3-6ubuntu3.1) ...
Processing triggers for mime-support (3.59ubuntu1) ...
Processing triggers for shared-mime-info (1.5-2ubuntu0.1) ...
Processing triggers for hicolor-icon-theme (0.15-0ubuntu1) ...
Setting up ntp (1:4.2.8p4+dfsg-3ubuntu5.4) ...
Installing new version of config file /etc/dhcp/dhclient-exit-hooks.d/ntp ...
/usr/sbin/addgroup: 32: /usr/sbin/addgroup: use: not found
/usr/sbin/addgroup: 33: /usr/sbin/addgroup: use: not found
/usr/sbin/addgroup: 34: /usr/sbin/addgroup: use: not found
/usr/sbin/addgroup: 35: /usr/sbin/addgroup: use: not found
/usr/sbin/addgroup: 38: /usr/sbin/addgroup: my: not found
/usr/sbin/addgroup: 43: /usr/sbin/addgroup: use: not found
/usr/sbin/addgroup: 44: /usr/sbin/addgroup: use: not found
/usr/sbin/addgroup: 45: /usr/sbin/addgroup: use: not found
/usr/sbin/addgroup: 46: /usr/sbin/addgroup: use: not found
/usr/sbin/addgroup: 47: /usr/sbin/addgroup: use: not found
/usr/sbin/addgroup: 52: /usr/sbin/addgroup: BEGIN: not found
/usr/sbin/addgroup: 53: local: not in a function
dpkg: error processing package ntp (--configure):
 subprocess installed post-installation script returned error exit status 2