Open the humblebook bundle download page and get the list of download URLs via the inspector's console with
Array.from(document.getElementsByClassName("a")).map(element => element.getAttribute('href')).filter(value => value && value.indexOf('dl.humble') != -1).join('\n')
Touch a files.txt
and fill it with the contents from the oneliner above. Then wget the files with wget -i files.txt
Rename the PDF, epub, and mobi files with
for i in *.epub?*; do mv $i ${i/\?*/}; done
for i in .pdf?; do mv