On Hadoop 3.x, we see following "ERROR: Tools helper ///usr/lib/hadoop/libexec/tools/hadoop-distcp.sh was not found." message on the first line of the command output when running Hadoop DistCp.
This message was added by
HADOOP-12857 and it would be an expected behavior.
DistCp calls 'hadoop_add_to_classpath_tools hadoop-distcp' when it starts, and the error is returned because the hadoop-distcp.sh does not exist in the tools directory.
However, that error message confuses us. Since this is not an user end configuration issue, I would think it's better to change the log level to debug (hadoop_debug).