How do I make Docker 'type'? -

i installing composer (a php tool) in docker container, , @ point installation script asks y/n option:

we initialize the application. proceed ? [y/n]  

how make dockerfile predict , answer in time?

you can echo selection , pipe scripts, assume need answer yes, yes, no script, can this: echo "y y n" | php composer.phar install or if want yes or no, can use yes yes y | php composer.phar install or yes n | php composer.phar.install