Check default domain name is more than zero length

src/freedombone-utils-web

@@ -762,10 +762,12 @@ function update_default_domain {
         fi
 
         if [ -d /etc/dovecot ]; then
-            if ! grep -q "ssl_cert = </etc/ssl/certs/${DEFAULT_DOMAIN_NAME}.pem" /etc/dovecot/conf.d/10-ssl.conf; then
-                sed -i "s|#ssl_cert =.*|ssl_cert = </etc/ssl/certs/${DEFAULT_DOMAIN_NAME}.pem|g" /etc/dovecot/conf.d/10-ssl.conf
-                sed -i "s|ssl_cert =.*|ssl_cert = </etc/ssl/certs/${DEFAULT_DOMAIN_NAME}.pem|g" /etc/dovecot/conf.d/10-ssl.conf
-                systemctl restart dovecot
+            if [ ${#DEFAULT_DOMAIN_NAME} -gt 0 ]; then
+                if ! grep -q "ssl_cert = </etc/ssl/certs/${DEFAULT_DOMAIN_NAME}.pem" /etc/dovecot/conf.d/10-ssl.conf; then
+                    sed -i "s|#ssl_cert =.*|ssl_cert = </etc/ssl/certs/${DEFAULT_DOMAIN_NAME}.pem|g" /etc/dovecot/conf.d/10-ssl.conf
+                    sed -i "s|ssl_cert =.*|ssl_cert = </etc/ssl/certs/${DEFAULT_DOMAIN_NAME}.pem|g" /etc/dovecot/conf.d/10-ssl.conf
+                    systemctl restart dovecot
+                fi
             fi
         fi