Re^4: Is there a way to open a memory file with binmode :raw? (open undef)

trying to figure out why Plack temporary files were being put into the wrong directory

On recent linux system you can find out the original location of the deleted file by examining /proc:

qwurx [shmem] ~> perl
open $fh, "+>", undef or die "Can't create anonymous storage: $!";
$file = "/proc/$$/fd/" . fileno $fh;
print "$file => ", readlink( $file ), $/;
__END__
/proc/26628/fd/3 => /tmp/PerlIO_eVAtFg (deleted)
[download]

On systems which lack /proc/$$/fd it can be quite annoying to find out, specially when the file system is full and a process is just sitting around in IOWAIT. In this condition there's a difference between disk usage of device and file system. Found that on an old Solaris server running a program which employed this trick: create file, get handle, unlink. Took me some time to find out.

perl -le'print map{pack c,($-++?1:13)+ord}split//,ESEL'

Comment on Re^4: Is there a way to open a memory file with binmode :raw? (open undef) Download Code

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Re^5: Is there a way to open a memory file with binmode :raw? (lsof) by tye (Sage) on Oct 13, 2015 at 16:58 UTC
`sudo lsof -p $PID` is what I usually use. Even more likely: `sudo lsof -p $PID \| grep -vw mem` [download] as I usually don't care about the rather large list of shared libraries that the process has open. Also: `sudo lsof /tmp \| grep deleted` [download] But, yes, lacking /proc makes the job harder for lsof. I haven't worked in such an environment recently, but I seem to recall lsof being able to report paths of deleted files that are still open on systems that didn't have /proc. Update: But note that the question that you quoted, "trying to figure out why Plack temporary files were being put into the wrong directory", is not answered by either of these approaches. These can answer "Where is Plack putting temporary files?". I already had the answer to that because I was asking "why". - tye	[reply] [d/l] [select]

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Re^5: Is there a way to open a memory file with binmode :raw? (lsof)
by tye (Sage) on Oct 13, 2015 at 16:58 UTC

sudo lsof -p $PID is what I usually use. Even more likely:

sudo lsof -p $PID | grep -vw mem
[download]

as I usually don't care about the rather large list of shared libraries that the process has open. Also:

sudo lsof /tmp | grep deleted
[download]

But, yes, lacking /proc makes the job harder for lsof. I haven't worked in such an environment recently, but I seem to recall lsof being able to report paths of deleted files that are still open on systems that didn't have /proc.

Update: But note that the question that you quoted, "trying to figure out why Plack temporary files were being put into the wrong directory", is not answered by either of these approaches. These can answer "Where is Plack putting temporary files?". I already had the answer to that because I was asking "why".

- tye

[reply]
[d/l]
[select]