pdftotext not found in CentOS
pdftotext is a tool in Linux that would extract any text readable, which was formatted prior from PDF. When you arrive on not able to find this helpful tools from Linux of your favorite distro, you can find it in the net for poppler utils which comprises the pdftotext binary file. It's codebase is base on XPdf 3.0. For CentOS, do yum install poppler* which would install the developer package, poppler package, and the util package of poppler. Hope this helps ;-).