Loading jdwp with HADOOP_CLIENT_OPTS throws an error

I'm trying to debug 'distcp' by setting any of the following options:

export HADOOP_CLIENT_OPTS="-Xdebug -Xrunjdwp:transport=dt_socket,address=5012,server=y,suspend=n"

export MAPRED_DISTCP_OPTS="-Xdebug -Xrunjdwp:transport=dt_socket,address=5012,server=y,suspend=n"

When I attempt to load jdwp with HADOOP_CLIENT_OPTS, 'NAMENODES' variable in 'start-dfs.sh' is incorrectly set to this value: "Listening for transport dt_socket at address: 5012 localhost".

When I attempt to load jdwp with MAPRED_DISTCP_OPTS, it is not even read by 'start-dfs.sh'

I followed the instructions specified here:

https://hadoop.apache.org/docs/r3.2.0/hadoop-project-dist/hadoop-common/UnixShellGuide.html

Goal is to debug 'distcp' so if there is an alternative way, that works as well.