File::Temp.. What am I missing?

devnul has asked for the wisdom of the Perl Monks concerning the following question:

Pulling another all-nighter and am gettin' some unwanted behavior from File::Temp.. Anyone know what I'm missing?

OS is FreeBSD 6.2, PERL is 5.8.8, if that matters

Here is code which reproduces this unwanted behavior:

use strict;
use File::Temp q/tempfile/;


for(my $i=0;$i<50;$i++)
{
  my $tmp = new File::Temp('DIR' => '/tmp', 'UNLINK' => 1);
  sleep(1);
}
[download]

What is going on is that as this script runs I can run "ls -l /tmp" and see the files being created and destroyed. But as soon as I hit ctrl-C to quit, the last temp file it created is still hanging around (otherwise known as the "unwanted behavior").

I would note that removing 'UNLINK' => 1 from the constructor, or using the my ($fh, $filename) = tempname('DIR' => '/tmp', 'UNLINK' => 1); produces the same result. The only reason I changed it from that was in an attempt to debug what is going on.

- dEvNuL

Comment on File::Temp.. What am I missing? Select or Download Code

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Re: File::Temp.. What am I missing? by chromatic (Archbishop) on Sep 29, 2008 at 03:47 UTC
It makes sense to me; you're interrupting a running program before it has a chance to finish. If you want to perform the kind of cleanup that your program doesn't get to (thanks to the interruption), install a signal handler for `SIGINT`. Like graff suggests, you can install a signal handler. Here's an easier approach though: `use strict; use warnings; use File::Temp 'tempfile'; $SIG{INT} = sub { exit }; for (0 .. 50) { my $tmp = File::Temp->new('DIR' => '/tmp', 'UNLINK' => 1); sleep(1); }` [download] With that change, the program will exit normally on `SIGINT`, rather than suffering an immediate exit. `END` and `DESTROY` code will run, which will clean up the temporary files.	[reply] [d/l] [select]
Re: File::Temp.. What am I missing? by graff (Chancellor) on Sep 29, 2008 at 03:38 UTC
Try writing your loop like this: `for(my $i=0;$i<50;$i++) { my $tmp = new File::Temp('DIR' => '/tmp', 'UNLINK' => 1); $SIG{INT} = sub { unlink "/tmp/".$tmp->filename; die }; ## <- add t +his line sleep(1); }` [download] Note that it's important to include the "die" call in the sub that gets assigned to $SIG{INT} -- otherwise, the script won't actually exit on ctrl-C. (Update -- to explain: when you interrupt the script, this will generally be during the sleep call, and unless you declare a signal handler to catch that, the File::Temp module will never get the chance to do its normal clean-up.) Another update -- check the perlipc docs, and your own system's manual regarding signals; you'll probably want to trap other things in addition to SIGINT (e.g. SIGTERM, which is what the shell "kill" command sends by default).	[reply] [d/l]
Re: File::Temp.. What am I missing? by ikegami (Patriarch) on Sep 29, 2008 at 03:57 UTC
On some systems (which should include FreeBSD), deleting the file while it's still open makes the file anonymous. It exists until the file no more file handles reference it. `for (1..50) { my $tmp = File::Temp->new( DIR => '/tmp' ); # Make the file anonymous unlink($tmp); sleep(1); }` [download] The above is still vulnerable to Ctrl-C, but only for a tiny amount of time. By the way, did you notice how much more readable the Perl-style for loop syntax is over the C-style one you used?	[reply] [d/l]