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Re: tmpfs and /tmp vs. /dev/shm



Hello

Darin Strait (<darin_strait@yahoo.com>) wrote:

> I'm running kernel 2.6.2 and I'm experimenting with tmpfs.
> 
> I added the following to my fstab:
> 
> tmpfs /tmp tmpfs   size=50m,mode=1777      0  0
> 
> 
> I then rebooted, just to be sure.
> 
> kiyone:/etc# mount
> /dev/hda1 on / type ext3 (rw,errors=remount-ro)
> proc on /proc type proc (rw)
> devpts on /dev/pts type devpts (rw,gid=5,mode=620)
> /dev/hda3 on /home type ext3 (rw)
> tmpfs on /tmp type tmpfs (rw,size=100m,mode=1777)
> tmpfs on /dev/shm type tmpfs (rw)
> sysfs on /sys type sysfs (rw)
> usbfs on /proc/bus/usb type usbfs (rw)
> 
> kiyone:/etc# df -h
> Filesystem            Size  Used Avail Use% Mounted on
> /dev/hda1             1.9G  1.6G  242M  87% /
> /dev/hda3             108G   88G   15G  86% /home
> tmpfs                 100M  608K  100M   1% /tmp
> tmpfs                 157M     0  157M   0% /dev/shm
> 
> 
> Now, I'd noticed the tmpfs filesystem at /dev/shm before. I naively
> assumed that it would evaporate once I modified fstab. Not so.
> 
> So, why do I have two tmpfs file systems?
> 
> Which one should my system be using, and how do I get rid of the other
> one?

The file system mounted on /dev/shm probably gets mounted through some
init script and does not depend on an entry in your fstab. I think the
script is linked to /etc/rcS.d/ and is calles something like kernfs. As
far as I know the script was introduced in Sid some weeks ago. This has
been discussed here before, just take a look at the archive.

best regards
        Andreas Janssen

-- 
Andreas Janssen <andreas.janssen@bigfoot.com>
PGP-Key-ID: 0xDC801674
Registered Linux User #267976
http://www.andreas-janssen.de/debian-tipps.html



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