Create config source. 

cat << EOF > toolconfig.env
UAT_MANAGEMENT_CAP_CLIENT_SERVER_IOR_URL=http://uat-content-management-server:8080/ior
UAT_MASTER_CAP_CLIENT_SERVER_IOR_URL=http://uat-master-live-server:8080/ior
UAT_REPLICATION_1_CAP_CLIENT_SERVER_IOR_URL=http://uat-master-live-server:8080/ior
UAT_REPLICATION_2_CAP_CLIENT_SERVER_IOR_URL=http://uat-master-live-server:8080/ior
# PROD
PROD_MANAGEMENT_CAP_CLIENT_SERVER_IOR_URL=http://prod-content-management-server:8080/ior
PROD_MASTER_CAP_CLIENT_SERVER_IOR_URL=http://prod-master-live-server:8080/ior
PROD_REPLICATION_1_CAP_CLIENT_SERVER_IOR_URL=http://prod-master-live-server:8080/ior
PROD_REPLICATION_2_CAP_CLIENT_SERVER_IOR_URL=http://prod-master-live-server:8080/ior
EOF

Export content to your host from UAT content-management-server. 

docker run --rm \
  --env-file=toolconfig.env \
  -e CONFD_PREFIX=uat/management \
  --volume $PWD/export:/export \
  coremedia/management-tools confd \
  tools/bincm serverexport -u admin -p admin \
  -r --basedir /export /

In the example above toolconfig.env is passed to docker and the environment variable CONFD_PREFIX is set to uat/management, which translates to the environment variable prefix UAT_MANAGEMENT_. In the env file the connection to the Content Management server is defined using the key UAT_MANAGEMENT_CAP_CLIENT_SERVER_IOR_URL. If the prefix had been set to uat/master the content repository of the master would have been used for the export.