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What online apps/services are there that would save my entries automatically as a Word or PDF file to my Dropbox folder with the title being the current date to archive journals as I write them?
Could not understand the question.. But assuming that you would need drobox to maintain your conflicts between Pdfs .. So for the answer . Try using git to maintain your pdfs.. It would be creating a bare git in one of your drobox folder.. Then adding the remote git add on the local folder in linux or macos .. Your pdfs need to be pushed to remote dropbox repo for your pdf file... So incase, your editing the pdf files, you would need to commit at every stage so that you could be happy with the conflicts.. P.S. You could also use github or any git service provider to achieve the above.
Write on PDF: All You Need to Know
Hope this help.