Cleaning /tmp on boot

[Paul Richards]

Hi,
Is there an easy way to have FreeBSD (RELEASE-5.3) clean /tmp on boot
by means of setting a flag or something in /etc/rc.conf? I'd like to
check before I start manually hacking up my boot scripts to get this
done.

Alternatively, is there something similar to tmpfs from Linux
available on FreeBSD? I've heard about mfs but it statically
allocates memory from the VM, I'd prefer if allocation was done only
as needed on demand.



--
Paul Richards

[Nelis Lamprecht]

On Thu, 24 Feb 2005 12:42:17 +0000, Paul Richards
<paul.richards@gmail.com> wrote:

> Hi,
> Is there an easy way to have FreeBSD (RELEASE-5.3) clean /tmp on boot
> by means of setting a flag or something in /etc/rc.conf? I'd like to
> check before I start manually hacking up my boot scripts to get this
> done.

I believe it's: clear_tmp_enable="YES"


Nelis

[Matthew Seaman]

On Thu, Feb 24, 2005 at 12:42:17PM +0000, Paul Richards wrote:

> Is there an easy way to have FreeBSD (RELEASE-5.3) clean /tmp on boot
> by means of setting a flag or something in /etc/rc.conf? I'd like to
> check before I start manually hacking up my boot scripts to get this
> done.

Add:

clear_tmp_enable="YES"

to /etc/rc.conf. Also consider 'daily_clean_tmps_enable="YES"' in
/etc/periodic.conf, which will enable a daily job to clean out old
files from temporary directories.

> Alternatively, is there something similar to tmpfs from Linux
> available on FreeBSD? I've heard about mfs but it statically
> allocates memory from the VM, I'd prefer if allocation was done only
> as needed on demand.

Yes -- correct, it is called 'mdmfs' under 5.x -- but it isn't
necessarily true that it allocates memory out of VM: depending on the
arguments used when configuring the underlying md(4) device, the
memory can be swap or file backed. When it's used to provide a /tmp
filesystem, it is specifically swap backed. As is explained in the
mdmfs(8) man page. Add the following to /etc/rc.conf to enable using a
memory filesystem for /tmp:

tmpmfs="YES"
tmpsize="128m"

Note that tmpsize should be smaller than the amount of swap space on
your machine -- preferably quite a bit smaller -- or you can end up
with a situation where any user can potentially DoS your server simply
by creating files under /tmp

Cheers,

Matthew

--
Dr Matthew J Seaman MA, D.Phil. 8 Dane Court Manor
School Rd
PGP: [url]http://www.infracaninophile.co.uk/pgpkey[/url] Tilmanstone
Tel: +44 1304 617253 Kent, CT14 0JL UK

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[Giorgos Keramidas]

On 2005-02-24 14:49, Nelis Lamprecht <nlamprecht@gmail.com> wrote:

>On Thu, 24 Feb 2005 12:42:17 +0000, Paul Richards
><paul.richards@gmail.com> wrote:

>> Hi,
>> Is there an easy way to have FreeBSD (RELEASE-5.3) clean /tmp on boot
>> by means of setting a flag or something in /etc/rc.conf? I'd like to
>> check before I start manually hacking up my boot scripts to get this
>> done.

>
> I believe it's: clear_tmp_enable="YES"

True. I'm just replying here to note that this and other tunables of
the rc.d scripts are documented in rc.conf(5):

% man rc.conf

If anyone happens to find an option that is not documented, then it's a
bug of the manpage and the freebsd-doc people will be glad to hear about
it; either with a simple post to the list or (preferably) through a new
problem report submission :-)

- Giorgos

[Lars Kristiansen]

> Alternatively, is there something similar to tmpfs from Linux

> available on FreeBSD? I've heard about mfs but it statically
> allocates memory from the VM, I'd prefer if allocation was done only
> as needed on demand.

Found these:
[url]http://docs.freebsd.org/cgi/mid.cgi?41E01905.3040200[/url]
[url]http://docs.freebsd.org/cgi/mid.cgi?45044.1105365790[/url]

So swap backed memory disks only swaps to disk when necessary.

Wish that could have been mentioned in the handbook or man-pages.
Should I try to PR that? Someone more knowledgeable will do it I hope :-)


--
Hilsen Lars

[Lowell Gilbert]

"Lars Kristiansen" <lars+lister.freebsd@adventuras.no> writes:

> > Alternatively, is there something similar to tmpfs from Linux
> > available on FreeBSD? I've heard about mfs but it statically
> > allocates memory from the VM, I'd prefer if allocation was done only
> > as needed on demand.

>
> Found these:
> [url]http://docs.freebsd.org/cgi/mid.cgi?41E01905.3040200[/url]
> [url]http://docs.freebsd.org/cgi/mid.cgi?45044.1105365790[/url]
>
> So swap backed memory disks only swaps to disk when necessary.
>
> Wish that could have been mentioned in the handbook or man-pages.
> Should I try to PR that? Someone more knowledgeable will do it I hope :-)

--- src/share/man/man4/md.4.ORIG Thu Feb 24 11:51:37 2005
+++ src/share/man/man4/md.4 Thu Feb 24 11:51:51 2005
@@ -50,7 +50,7 @@
This allows for mounting ISO images without the tedious
detour over actual physical media.
.It Cm swap
-Backing store is allocated from swap space.
+Backing store is allocated from virtual memory space.
.El
.Pp
For more information, please see

Feel free to PR.
--
Lowell Gilbert, embedded/networking software engineer, Boston area
[url]http://be-well.ilk.org/~lowell/[/url]

[Lars Kristiansen]

Lowell Gilbert skrev:

>"Lars Kristiansen" <lars+lister.freebsd@adventuras.no> writes:
>
>
>

>>>Alternatively, is there something similar to tmpfs from Linux
>>>available on FreeBSD? I've heard about mfs but it statically
>>>allocates memory from the VM, I'd prefer if allocation was done only
>>>as needed on demand.
>>>
>>>

>>Found these:
>>[url]http://docs.freebsd.org/cgi/mid.cgi?41E01905.3040200[/url]
>>[url]http://docs.freebsd.org/cgi/mid.cgi?45044.1105365790[/url]
>>
>>So swap backed memory disks only swaps to disk when necessary.
>>
>>Wish that could have been mentioned in the handbook or man-pages.
>>Should I try to PR that? Someone more knowledgeable will do it I hope :-)
>>
>>

>
>--- src/share/man/man4/md.4.ORIG Thu Feb 24 11:51:37 2005
>+++ src/share/man/man4/md.4 Thu Feb 24 11:51:51 2005
>@@ -50,7 +50,7 @@
> This allows for mounting ISO images without the tedious
> detour over actual physical media.
> .It Cm swap
>-Backing store is allocated from swap space.
>+Backing store is allocated from virtual memory space.
> .El
> .Pp
> For more information, please see
>
>Feel free to PR.
>
>

Thank you, done. (or tried to)
[url]http://www.freebsd.org/cgi/query-pr.cgi?pr=78041[/url]


--
Still dark.
Hilsen Lars