Hey,

The /user/ directory is owned by "hdfs" with 755 permissions. As a result only hdfs can write to that directory. Unlike unix/linux, hdfs is the superuser and not root. So you would need to do this:

sudo -u hdfs hadoop fs -mkdir /user/,,myfile,,
sudo -u hdfs hadoop fs -put myfile.txt /user/,,/,,

If you want to create a home directory for root so you can store files in his directory, do:

sudo -u hdfs hadoop fs -mkdir /user/root
sudo -u hdfs hadoop fs -chown root /user/root

Then as root you can do "hadoop fs -put file /user/root/".

Hope this helps.

Chris