Launch YaST:
Choose Category “System”, then “Editor for /etc/sysconfig Files”.

Then open “System” and after that open “Cron”.

Here you find the following Entrys:

CLEAR_TMP_DIRS_AT_BOOTUP = “no”
Change to: “yes”
That means: enable or disable the Cleanup Function global.
Default: “no” (=off!)

TMP_DIRS_TO_CLEAR = “/tmp”
That you can leave.
That means: First List from Folders, that can be deleted.
Default: /tmp

MAX_DAYS_IN_TMP = 0
Change to: “1” (=deletes all Files who are older than 24h)
Means: Max. File Lifetime in days. That is for the Files, defined in TMP_DIRS_TO_CLEAR.
Default: 0 (=disabled)

Close the Editor. You see all changes and you can close the Editor.

Close “YAST”
In the next Systemstart cron cleans up your /tmp.

You can define an second List:

LONG_TMP_DIRS_TO_CLEAR = “”
Means: second Folderlist who can be deleted.
Default: “”
Possible Option: “/var/tmp”

MAX_DAYS_IN_LONG_TMP = 0
Means: Max File Lifetime in days, for all Files who are defined in LONG_TMP_DIRS_TO_CLEAR.
Default: 0 (= disabled)
Possible Option: “28″

Based on Reinhard Haase’s HowTo on: http://tiefenwirkung.wordpress.com/2009/07/19/temporare-dateien-unter-linux/