If you download a pdf from the journal very often it has a cryptic name.
I guess most of us are using Mendeley etc... but if you need from time to time rename your pdf files, don't forget about pubmex :-)
Pubmex a script to get a fancy paper title based on given DOI or PMID.
If you submit DOI `10.1007/978-1-60761-863-8_2` you will get `Shepherd.Ibba.Bacterial.transfer.RNAs.FEMSMicrobiolRev.2015.pdf`.
You can use Python script to "watch" your folder for pdfs and change their names automatically.
It is very old, I think I wrote the first version 6-7 y ago :-) right now I use Mendeley, but I use the web server from time to time if I want to send a pdf to someone else.
The standalone version is here (https://github.com/m4rx9/pubmex )and the web server is here (http://pubmex.alwaysdata.net/ ).