Setting up a RAM drive on Raspberry Pi

Introduction

It is strongly believed that excessive writing to the Raspberry Pi's SD card will finally cause it to fail. But the only way to exchange data between Lua and shell scripts is through temporarily files. 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.

For more elaborate instructions, see Moving Log and Temporary Files To a RAM Drive

Setup

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

 pi@raspberrypi ~ $ df
 Filesystem     1K-blocks    Used Available Use% Mounted on
 rootfs           3807952 1814024   1820896  50% /
 /dev/root        3807952 1814024   1820896  50% /
 devtmpfs          183596       0    183596   0% /dev
 tmpfs              38372     268     38104   1% /run
 tmpfs               5120       0      5120   0% /run/lock
 tmpfs              76740       0     76740   0% /run/shm
 /dev/mmcblk0p1     57288   18544     38744  33% /boot
 tmpfs               1024       4      1020   1% /var/tmp

This should give you a small space for your garbage. Instead of writing your tmp files to /tmp, now write them to /var/tmp. And remember that, as is generally the case with RAM drives, data on the drive is lost after a reboot.