/tmp on multi-FS set-ups, or: block users from using /tmp?

[Ivan Shmakov <oneingray@gmail.com>]

>>>>> Weldon Goree <weldon@b.rontosaur.us> writes:
>>>>> On Fri, 2012-05-25 at 10:02 -0400, Nikolaus Rath wrote:

 >> I think having / and /tmp share the same file system is a bad idea,
 >> because then writing lots of stuff to /tmp would potentially fill up
 >> the root file system (that typically also includes /var) and then
 >> cause a lot of breakage.

 >> However, if I put /tmp in a separate (on-disk) file system, I have
 >> to decide how much disk space to I want to permanently allocate for
 >> temporary data, in addition to the disk space permanently allocated
 >> for swapping.

[…]

	Somehow, I feel that some of the participants of this discussion
	are missing this very point: having /tmp on disk /doesn't/ mean
	that /all/ the free disk space will be available for it at any
	given time.

	In particular, as Ext2+ filesystems can only be expanded, and
	not reduced (without unmounting), I've got the habit of having
	most of the disk space unallocated, and only expanding the
	filesystems as they grow full.  (Unless, of course, considerable
	amounts of cruft could be identified and removed at that time.)

 > If only ext*fs supported quotas...

	… But that makes me recall a solution to both the /tmp and quota
	issues I've seen somewhere: use ~/tmp/ instead of /tmp.  This
	way, user's temporary files will be subject to exactly the same
	limits as all the other his or her files.

	(Still, we may need to identify the software that ignores TMPDIR
	and tries to write to /tmp unconditionally.)

 > (Snark aside, does tmpfs support quotas yet/will it ever?)

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