Inside double-quotes, a *
is a literal *
character. To use it to match "any character except /
" it must be outside of the double-quotes. Try these two commands in Terminal to see the difference:
ls "$HOME/Desktop/*"
...and:
ls "$HOME/Desktop/"*
So your command needs to be:
"/System/Library/Automator/Combine PDF Pages.action/Contents/MacOS/join" -o "$HOME/Documents/Dropbox/JL IMAC backup of important systems files/Natural Readers/Combined PDF.pdf" "$HOME/Documents/Dropbox/JL IMAC backup of important systems files/Natural Readers/"*.pdf
(I've tidied up the quoting/escaping a bit -- while you can mix-and-match double-quoted strings and \
-escaping, it's easier to read and troubleshoot if you pick one or the other when you can.)