[Novalug] where are they?
Mark Smith
mark@winksmith.com
Tue Mar 10 16:50:33 EDT 2015
oh, and as an example:
1. create a 1GB file and note the size of your file system.
dd if=/dev/zero of=/tmp/zero bs=1M count=1000
df -h /tmp/
2. for the file descriptor to remain open:
sleep 1h < /tmp/zero &
3. delete the reference to the file within the directory:
rm /tmp/zero
4. note the file system size has NOT gone done by a GB.
df -h /tmp/
5. kill your 'sleep' thus releasing the open file descriptor. then note
the file system size NOW has gone done by the appropriate amount:
kill %%
df -h /tmp/
On Wed, Mar 11, 2015 at 09:22:43AM +1300, Mark Smith via Novalug wrote:
> On Tue, Mar 10, 2015 at 10:05:01AM -0400, John Franklin via Novalug wrote:
> > A common thing for applications to do is create and open a temp file, then "unlink" it from the filesystem. This both prevents other snooping processes from getting a handle to it and ensures the temp file is freed when the process dies, even if it is from an uncaught SIGKILL.
>
> a useful side-effect of this is that no one else can open and peek into
> your temp file too. you can put whatever you want into it fairly safely.
> there is no filename, so what would you open?
--
Hei konā mai
Mark Smith
mark@winksmith.com
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