A report was printed via a session that cannot be done again. The user didn't save the report file. So, they want to have that report file.
We tried to search for tmp files in the server to see if we could get the report that way, but no luck. The tmp files cannot be opened even though we changed the extension to .pdf.
We even tried renamed the extension of the tmp file to .bpf and opened it with bwprint, but only get the xml-like codes as text as a result.
How to reprint a report from tmp file?
or, better, is there any other way to achieve this task?

I guess you tried to reprint it using the Device Queue (ttaad3520m000) and it didn't work?
It may be, that the setup of the printer is not keeping the output. (This is our setup of the display device in LN 10.7. It generated an PDF, but this will be deleted right after printing is completed).

All I can think of, if you have the tmp file and it does contain readable characters, is trying to convert it with an editor (I use Ultraedit, others use Notepad+). So, you will be able to restore most of the printed information, but not the PDF itself.

In 4c4 when we setup users we had a delete delay time for the users. What that did was how long to keep the tmp files before they were deleted. Now as Andreas mentioned you can use the device queue to try to re-print the report - but if I recall on our system after about 2 days you could not reprint from the device queue (could have been 1 day).

Thanks @andreas.toepper and @mark_h.
I did try the Device Queue (ttaad3520m000) but there is no record for that report to reprint. Maybe it is deleted as you suggested.
Is there any other way?

It may depend on the setup of the printer. If you are using DOM (Document Output Management) there may be a directory in BSE/tmp, which holds copies of generated output (it may be call "outbox"). But I think this is related to creating mails from LN with DOM.
Maybe the user downloaded the PDF on his client, then you may want to check the download list of the used browser. I don't think you may find something in the browser cache.

A report was printed via a session that cannot be done again. The user didn't save the report file. So, they want to have that report file.
We tried to search for tmp files in the server to see if we could get the report that way, but no luck. The tmp files cannot be opened even though we changed the extension to .pdf.
We even tried renamed the extension of the tmp file to .bpf and opened it with bwprint, but only get the xml-like codes as text as a result.
How to reprint a report from tmp file?
or, better, is there any other way to achieve this task?tmp files in the $BSE/tmp are "short lived" (depending on sysadmin setup effort) but normally (depeding on device queue) if you have the correct file (grep on content keywords) renaming the file to tmp*.bpf and opening the file in bwprint could work.