Thank you very much for your answer, but I'm a bit confused: I read the link and that CALIBRE_TEMP_DIR is not an actual directory, but an envoronment variable, which I don't know what it is... I clicked then on "HowTo: Set an Environment Variable in Mac OS X - launchd.plist", but with the same result: I don0t know what those codes are and where or how should I write them
However, since you say it is a matter of temporary files, It may be cleanmymmac's fault. On this app I see I can exclude some folders. I you could tell me where those temporary files not to be deleted are stored, I could give a try
