Today I got so annyed by firefox's default behaviour of downloading each and every PDF file to my disk that I went searching for a solution until I had the problem fixed. And it seems like I have finally found it. I have linked the solution but here is the fix in short:
go to about:config
change browser.download.open_pdf_attachments_inline to true
After watching other comments I wonder why some people don't get that this was a bug or at the very least, undocumented behavior outside of the Settings GUI. I had to deal many times with file (4).pdf on my Downloads dir. A BIG thank you, OP.
it isn't in right in firefox's settings -> general -> under 'files and applications' ??
'open in firefox' (what you want), vs 'always ask', 'always save' (download) or 'open in default application' (such as adobe reader). actions are configurable for many file types.
I believe even if you choose “Open in Firefox”, it will still download the PDF to the default download directory before opening it inside a Firefox tab. The behavior that OP describes above seems to prevent that downloading (and having the file around in your default download directory).
I don't know whether they fixed it since, but last I checked that option was broken.
No matter what you select, half the time it still downloads the PDF to your drive.
It does not fix the bug, i want to save in tmp & use external application like it did until last year
I don't want to have the same behaviour of chromium browsers, otherwise i would use chromium browsers.
Luckily microsoft updated ms edge on linux to save on tmp the files that you want to open, but you don't want to save. It's the only browser left that does that with a simple check in settings and doesn't require big workarounds. Used to be only firefox to do this... pity
That sounds like browser.download.start_downloads_in_tmp_dir combined with “open with…”. That setting should download to tmp whenever you open it directly in an application. The other setting (browser.download.open_pdf_attachments_inline) should only be enabled if you want to open PDFs in the browser without downloading them.
Iirc, I had to set that firefox doesn't open everything in the browser but downloads the pdfs to disk. It was in the settings.
I really didn't get the idea why I had to save pdfs manually. To me, it feels weird to not save pdfs automatically but I understand you if you rarely safe a pdf.
You can specify where you want the temp download folder to be fyi. It's in the normal settings. Just make a folder in like C:/firefox temp files and have it dump all that shit in there.
Even with browser.download.open_pdf_attachments_inline set to false (default), Firefox already opens PDFs instead of downloading them, thanks to this setting:
For me it still downloads and then opens it in firefox. In the description it clearly says: Choose how Firefox handles the files you download from the web (...). And I don't want it to download the file to my disk in the first place just store it in chache like a regular website.
Because you don't always want to permanently save to the drive the PDFs you find on the internet, often you just need to skim them and that's it, just like a webpage
It keeps being downloaded as a regular download to the default download folder, filling up disk space and the file needs to be deleted by explicit command. With the change it's a temporary download and is erased when cache is purged.
PDFs are particularly annoying like that. On one hand most browsers offer to open them in the browser, but on the other hand it's a "file" rather than a document. Imagine if your browser decided to download all the HTML webpages that you visit to your download folder, instead of the temporary cache. That's how PDFs are handled.
To make it more complicated, sometimes you'll want that and other times you don't.
It's also really annoying in terms of GDPR compliance, because some users gather a lot of PDFs in their download folder without even realising it. I empty my download folder daily, just like the trashcan, just to be sure that I'm not keeping things that I'm not supposed to keep. This is only/mainly due to the browsers handling of the PDF format.