Read/Writing as a different user

gistfile1.txt

» ~  docker run -u nobody -i -t ubuntu touch /tmp/test      
» ~  
» ~  docker ps -l
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES
b360de514896        ubuntu:12.04        touch /tmp/test     5 seconds ago       Exit 0                                  distracted_torvalds   
» ~  docker commit b360de514896
73f2406aa2cd26d503992f9cfc8e28212bb0513f33094f74b34f4ed1e175c7bc
» ~  docker tag 73f2406aa2cd26d503992f9cfc8e28212bb0513f33094f74b34f4ed1e175c7bc nobody-test
» ~  docker run nobody-test ls -l /tmp
total 0
-rw-r--r-- 1 nobody nogroup 0 Feb  7 19:11 test