6.2.15 Ensure all groups in /etc/passwd exist in /etc/group (Scored)

Level 1 - Server
Level 1 - Workstation 

Over time, system administration errors and changes can lead to groups being defined in /etc/passwd but not in /etc/group.

Groups defined in the /etc/passwd file but not in the /etc/group file pose a threat to system security since group permissions are not properly managed.

Run the following script and verify no results are returned:

#!/bin/bash 
for i in $(cut -s -d: -f4 /etc/passwd | sort -u ); do
  grep -q -P "^.*?:[^:]*:$i:" /etc/group 
  if [ $? -ne 0 ]; then 
    echo "Group $i is referenced by /etc/passwd but does not exist in /etc/group" 
  fi 
done

Analyze the output of the Audit step above and perform the appropriate action to correct any discrepancies found.