[ale] cleaning out /tmp

[Daniel Kahn Gillmor]

On Mon 2007-09-03 11:45:26 -0400, Michael B. Trausch wrote:

> Hrm.  That's some odd behavior, I would think.  Why would a program
> do that... it would seem that it is saving state in /tmp by doing
> that, but really shouldn't it be using /var/* for that purpose?

That'd be ideal, but not all programs are system-level programs, and
so they don't have designated space in /var for such storage.

For example, the default location for a krb5 credentials cache for a
user with uid 1234 is /tmp/krb5cc_1234.  That ccache is hardly ever
actually held open by a process: it's only briefly scanned (and maybe
updated) upon authentication, then released.  If you were to purge a
user's ccache, they'd suddenly be unable to authenticate to the
systems they expected to.  If i were a user on that system, i'd be
rather frustrated.

If yer gonna be trying to clean the /tmp dir on a live system, you
should have atime turned on for that filesystem, and you should only
remove files that haven't been accessed for > 48 hours or something.

Even easier than cleaning up /tmp manually on reboot is to just mount
it as a tmpfs anyway, so it's only held in RAM (backed by swap, of
course, should it be necessary):

[0 dkg at squeak ~]$ grep /tmp /etc/fstab
tmp /tmp tmpfs nosuid,nodev,mode=1777 0  0
[0 dkg at squeak ~]$ 

hth,

   --dkg
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