bind /tmp to /dev/shm on Ubuntu

After upgrading my PC to 16G of memory, I thing I can move something to memory instead of keeping them on disk.
Chome is my daily used software, and yes, chrome keep lots of caches. To help speed up chrome, I decide to move chrome's cache to memory for testing.
Here are the steps:

  rm -r ~/.cache/google-chrome
  mkdir /dev/shm
  ln -s /dev/shm/chrome ~/.cache/google-chrome

Yeah, it's simple and it works. So lets go further to bind /tmp to /dev/shm too.
First, open vi or gedit as root.
Then create /etc/init.d/ramdisk.sh

  #!/bin/sh
  # RamDisk tmp
  PATH=/sbin:/bin:/usr/bin:/usr/sbin

  mkdir /dev/shm/tmp
  chmod 1777 /dev/shm/tmp
  mount --bind /dev/shm/tmp /tmp

And make it executable.

  sudo chmod 755 /etc/init.d/ramdisk.sh 

Now, we can just run the script to mount /tmp on /dev/shm/tmp. However it will be restored to default after reboot. So we need to run it on boot.

  cd /etc/rcS.d
  sudo ln -s ../init.d/ramdisk.sh S50ramdisk.sh

Now, it's done. You can also move /var/tmp to /dev/shm to keep temporary files in memory instead of disk but it might have side-effects.
Have fun!

reference:
[教學] /tmp 設到 RadmDisk (tmpfs) 的方法
Change Chrome cache directory in Ubuntu