$ wget https://downloads.wkhtmltopdf.org/0.12/0.12.5/wkhtmltox-0.12.5-1.centos7.x86_64.rpm
$ yum install wkhtmltox-0.12.5-1.centos7.x86_64.rpm
Make sure /usr/local/bin is in $PATH
$ echo $PATH
if not, add it to your .bash_profile
PATH=$PATH:$HOME/bin:/usr/local/bin
$ wkhtmltopdf http://www.google.com google.pdf