prhodes@troubadour:~/Downloads/pdfs$ find . -name "*.pdf" | wc -l
    18952
    prhodes@troubadour:~/Downloads/pdfs$ find . -name "*.epub" | wc -l
    2385
    prhodes@troubadour:~/Downloads/pdfs$ find . -name "*.djvu" | wc -l
    1384
    prhodes@troubadour:~/Downloads/pdfs$ find . -name "*.mobi" | wc -l
    125