title: What's the difference between yum -y install and yum install in CentOS
body: <p>I've seen two ways to install packages,for example,squid on CentOS:</p>
  
  <p>1.<code>yum -y install squid</code></p>
  
  <p>2.<code>yum install squid</code></p>
  
  <p>can anyone tell me what's the difference between them ?
  also, I'm using CentOS v.6.6 </p>