@@ -1408,13 +1408,17 @@ The following environment variables are set for Linux containers:

 Additionally, the operator can **set any environment variable** in the

 container by using one or more `-e` flags, even overriding those mentioned

-above, or already defined by the developer with a Dockerfile `ENV`:

+above, or already defined by the developer with a Dockerfile `ENV`. If the

+operator names an environment variable without specifying a value, then the

+current value of the named variable is propagated into the container's environment:

 ```bash

-$ docker run -e "deep=purple" --rm alpine env

+$ export today=Wednesday

+$ docker run -e "deep=purple" -e today --rm alpine env

 PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin

 HOSTNAME=d2219b854598

 deep=purple

+today=Wednesday

 HOME=/root

 ```