Converting images (Jpeg, png, etc) to PDF on linux

Pop up a terminal.

$ sudo apt-get install imagemagick
$ convert img1 [img2...] output.pdf

If your files are already in alphabetical order, bash can automatically expand:

$ convert *.jpg output.pdf

If you want to limit the target file size, play around with -quality VALUE:

$ convert -quality 30 *.jpg output.pdf

Voilà!