TMPFS

To avoid SD card wearing these files could be written to a virtual drive in RAM. This guide shows how to set up a 1 MB RAM drive on your Raspberry Pi.

Goal is to have a 1MB directory in RAM for temporarily storage. First create the tmp dir:

sudo mkdir /var/tmp

then edit the fstab file by

 sudo nano /etc/fstab

and add the line

 tmpfs /var/tmp tmpfs nodev,nosuid,size=1M 0 0

save and close the file. Now issue

 sudo mount -a

To check if your operation succeeded issue

 df

which should report (among the other disks) a tmpfs with 1024 1K blocks (=1MB) as /var/tmp

http://www.domoticz.com/wiki/Setting_up_a_RAM_drive_on_Raspberry_Pi