How to check if a group exists and add if it doesn't in Linux Shell Script

Question

this is a summary of what i want my code to do:

if (group exists) then    (add user to group)  else    (create group)    (add user to group)  fi 

I am using the Ubuntu virtual machine but all of the results i have found on similar sites do not work.

Answer 1

The grep statement in the solution of rups has some flaws:

E.g. grepping for a group admin may return true ("group exists") when there is a group lpadmin.

Either fix the grep-query

grep -q -E "^admin:" /etc/group 

or use

if [ $(getent group admin) ]; then   echo "group exists." else   echo "group does not exist." fi