Get a few lines of HDFS data

You can use head command in Hadoop too! Syntax would be

hdfs dfs -cat <hdfs_filename> | head -n 3

This will print only three lines from the file.

Native head

hadoop fs -cat /your/file | head

is efficient here, as cat will close the stream as soon as head will finish reading all the lines.

To get the tail there is a special effective command in hadoop:

hadoop fs -tail /your/file

Unfortunately it returns last kilobyte of the data, not a given number of lines.