docker build -t php-htmldiff . docker run -i -t --privileged -v $PWD/docker-ws:/root --workdir=/root php-htmldiff /bin/bash php htmldiff.php old.html new.html > diff.html 
There is a message like below one.(when dokcer build)
Do not run Composer as root/super user! See https://getcomposer.org/root for details