CODEWITHSUNDEEP
perl
Adrian Smith
Adrian Smith

Reputation: 17553

Delete file on exit

Maybe I'm wrong, but I am convinced there is some facility provided by UNIX and by the C standard library to get the OS to delete a file once a process exits. But I can't remember what it's called (or maybe I imagined it). In my particular case I would like to access this functionality from perl.

Java has the deleteOnExit function but I understand the deletion is done by the JVM as opposed to the OS which means that if the JVM exits uncleanly (e.g. power failure) then the file will never get deleted.

But I understand the facility I am looking for (if it exists), as it is provided by the OS, the OS looks after the file's deletion, presumably doing some cleanup work on OS start in the case of power failure etc., and certainly doing cleanup in the case the process exits uncleanly.

Upvotes: 2

Views: 2845

Answers (5)

ysth
ysth

Reputation: 98388

If you are looking for something that the OS may automatically take care of on restart after power failure, an END block isn't enough, you need to create the file where the OS is expecting a temporary file. And once you are doing that, you should just use one of the File::Temp routines (which even offer the option of opening and immediately unlinking the file for you, if you want).

Upvotes: 5

Geo
Geo

Reputation: 96797

You could do your work in an END block.

Upvotes: 0

Mridul Kashatria
Mridul Kashatria

Reputation: 4187

I think you are looking for a function called tmpfile() which creates file when called and deletes it upon close. check, article

Upvotes: 2

geekosaur
geekosaur

Reputation: 61369

You're looking for atexit(). In Perl this is usually done with END blocks. Java and Perl provide their own because they want to be portable to systems that don't follow the relevant standards (in this case C90).

That said, on Unix the common convention is to open a file and then unlink it; the kernel will delete it when the last reference (which is to say, your file descriptor) is closed. You almost always want to open for read+write.

Upvotes: 2

Chris Eberle
Chris Eberle

Reputation: 48775

A very very simple solution to this (that only works on *nix systems) is to:

  1. Create and open the file (keep the file handle around)
  2. Immediately call unlink on the file
  3. Proceed as normal using the file handle, and exit when you feel like it

Then when your program is complete, the file descriptor is closed and the file is truly deleted. This will even work if the program crashes.

Of course this only works within the context of a single script (i.e. other scripts won't be able to directly manipulate the file, although you COULD pass them the file descriptor).

Upvotes: 10

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