Send a request to the website 'http://www.random.org/strings/' with the user agent "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.87 Safari/537.36", accept header "application/json", and parameters "num=1, len=32, digits=on, upperalpha=on, loweralpha=on, unique=on, format=plain, rnd=new". Then, remove all characters except for alphanumeric characters and fold the result into 16 character strings. Finally, take the first string from the result.
curl -A "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.87 Safari/537.36" -H "Accept: application/json" 'http://www.random.org/strings/?num=1&len=32&digits=on&upperalpha=on&loweralpha=on&unique=on&format=plain&rnd=new' | tr -dc "[:alpha:][:digit:]" | fold -w 16 | head -n 1