问题
I want to create a temporary file on linux while making sure that the file will disappear after my program has terminated, even if it got killed or someone performs a hard reboot in the wrong moment. Does tmpfile() handle all this for me?
回答1:
You seem pre-occupied with the idea that files might get left behind some how because of some race condition, I don't see an explanation of why this is a concern.
"A race condition occurs when a program doesn't work as it's supposed to because of an unexpected ordering of events that produces contention over the same resource."
I was assuming that from your comments on other answers your concern was specifically on a dead-lock which is a result of trying to remediate a race-condition ( contention of the shared resource ). It is still not clear what your concern is, calling tmpfile() and having the program exit abnormally before that function gets to call unlink() is the least of your worries if your application is really that fragile.
Given that there isn't any mention of concurrency, threading or other processes sharing this file descriptor to this temp file, I still don't see the possibility for a race condition, maybe the concept of an incomplete logical transaction, but that can be detected and cleaned up.
The correct way to make absolutely sure that any allocated file system resources are cleaned up is not solely on exit of an application but also also on start-up. All my server code, makes sure that everything is cleaned up from a previous run before it starts and makes itself available.
Put your temp files in a sub-dir in /tmp make sure your application cleans this sub-dir on startup and normal shutdown. You can wrap your app start up with a shell script that detects abnormal ( kill -9 ) shutdown based on PID existence and also does clean up activities.
回答2:
If you don't want to use tmpfile(), you can unlink() your file immediately after creating it. It will stay open and present and allocated until it is closed.
But on a hard reboot, a fsck might be needed in order to recover the space. But as this is always the case, it is no special drawback of this approach.
回答3:
according to tmpfile() man page:
The file will be automatically deleted when it is closed or the program terminates.
I have not tested, but it seems it should do what you want.
Moreover:
The default location, if TMPDIR is not set, is /tmp.
Then, when a reboot is produced, /tmp will be empty.
回答4:
EDIT: Yes
I checked the tmpfile source, and it does indeed use glglgl trick, and instantly unlocks the file.
Original:
I would say no. Got killed should work, but I would assume that it can happen, that after a hard reboot (e.g. due to power outtake) the file is still there. But that depends on your Linux distribution and the used settings.
If the temp file is created in a ramdisk, it is gone (there are unix distris out there that e.g. use a ram based tmpfs for temporary files).
Or if you use an environment that has certain policy regarding tmp, it could be also gone (maybe not instant, but often there are policies, like e.g. remove all files in /tmp that are not accessed within one month), but it could be also on a standard file system where such rules are not enforced. In this case the file would stay.
回答5:
The customary approach is to set up a signal handler to clean up if the program is interrupted. This will not handle kill -9 or a physical reboot, which can't be trapped. Create temporary files in /tmp, which is normally cleaned out when the system boots. All that remains then is to teach people not to use kill -9 when they don't need to, but that appears to be an uphill battle.
回答6:
In linux, mktemp command works.
来源：https://stackoverflow.com/questions/9889277/how-to-create-temporary-files-on-linux-that-will-automatically-clean-up-after-th