if [ ! -f myfile ]
then
   cat <<EOF > myfile
server {
    listen 80 default_server;
    listen [::]:80 default_server;
    server_name $server ;
    root /usr/share/nginx/html;
}
EOF
fi

##read from A file write to B file

sed -i -e '1r new_file' -e 'wq' file

sed -e '2s/^/#/' -e '5s/^/#/' -e '7s/^/#/'  file

 sed '/:8080;/s/^/#/g'  file