Use "ImageMagick" which can be installed easily on most UNIX/Linux distros.
Remember that it will go with the standard file listing to determine the order but I believe you can manually specify multiple jpg's in the arguments.
Convert image/jpg to PDF
convert *.jpg yourpdf.pdf
This is a very handy and free tool.
Convert DOC/TXT documents to PDF
If you wanted to convert a .doc file or text of any kind, you could use OpenOffice Writer/Wordprocessor and choose "Export as PDF".
convert, images, jpg, jpeg, pdfuse, quot, imagemagick, installed, unix, linux, distros, listing, determine, manually, specify, multiple, arguments, pdf, yourpdf, txt, documents, text, openoffice, wordprocessor, export,