Lists the names of all HDFS directories containing data in the specified path.
A path relative to the current default path. The default path is the current working directory.
This example lists the subdirectories in the current directory:
R> hdfs.ls()
[1] "ontime_DB"   "ontime_FILE"   "ontime_R"
The next example lists directories in the parent directory:
R> hdfs.ls("..")
[1] "demo"   "input"   "output"   "sample"   "xq"
This example returns NULL because the specified path is not in HDFS.
R> hdfs.ls("/bin")
NULL