create new user with specified credentials for limited time and add him to a desired group

create-user-hackt.sh

USERNAME="johndoe"
PASSWD="xxxxxxxx" 
FULLNAME="John Doe"
sudo useradd ${USERNAME} -b /home/hackathon -m -s /bin/bash -e 2023-09-02 -c "${FULLNAME} - guest user for hackathon" && \
echo $USERNAME, ${FULLNAME} " created!"
echo "${USERNAME}:${PASSWD}" | sudo chpasswd && \
        echo "password set for ${USERNAME}"
sudo usermod -a -G grphackt ${USERNAME} && \
        echo "user added to shared group"