/tmp is cleaned at boot by the Upstart script /etc/init/mounted-tmp.conf. If you look at that file, you see that there are no ways to tell it not to do his job. However you are free to modify it.

Here's how I'd proceed:

1. At the very end of mounted-tmp.conf (just before end script), place the following:

   
   
   

    touch /tmp/.notclean
   
   

   
   
   

   This way, every time /tmp is mounted, a file .notclean will be created.




2. After the following line (which is the line before the script starts removing files)...

   
   
   

    cd "${MOUNTPOINT}" || exit 1
   
   

   
   
   

   ...check for the existence of .notclean. If the file exists, it means that the computer did not shutdown cleanly.

   
   
   

    cd "${MOUNTPOINT}" || exit 1
   
    [ -f .notclean ] && exit 0
   
   




3. Now you need a new Upstart script that removes .notclean on shutdown. Create /etc/init/mark-tmp-clean.conf and place this code:

   
   
   

    description "some useful description"
   
    start on starting rc
   
    task
   
    script
   
        rm -f /tmp/.notclean
   
    end script