You can use the convert tool:
convert 1.jpg 1.png 2.txt a.pdf the_new.pdf
This is more a note for me but I hope it helps someone.
I needed to import an OpenOffice Drawing file (.odg) into Google Docs. Unfortunately Google Docs doesn’t open .odg files natively and there isn’t a file format which you can export / save the OpenOffice drawing file as which contains all the information in an editable format. I found the only way to transfer all the information was to:
I hope this helps someone.