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How to Use Special Keys in UNIX

UNIX operating system has some special keys. These you can use to interrupt the program processing or to resume it. The file management and keys totally different in UNIX kinds of operating systems. 



An example of a UNIX special key and its use.
Special Keys in UNIX much useful to take action  when something happens.

1. Why You Need Program Interruption in UNIX.

A scenario where you made some mistake in the input command and you need to stop the further process. Then you can use the CTRL+C command. It is equal to the DELETE command.

2. List of UNIX Special Keys.

RETURN key 
The RETURN key signifies the end of a line of input. On any terminal, RETURN has a key of its own, or return may be typed by holding down the control key and typing a 'm'.

CTRL-m Key
Hint: Ctrl-m command is equal to RETURN key in Unix systems


DELETE Key
The DELETE key stops a program/command immediately, without waiting for it to finish. DELETE can be achieved equivalently with ctrl-c.
Hint: Ctrl-c Command you can use …

The best helpful HDFS File System Commands (2 of 4)

Hadoop+Big data+Jobs, Apply Now
#Top-Selected-HDFS-file-system-commands
CopyFrom Local
Works similarly to the put command, except that the source is restricted to a local file reference.
hdfs dfs -copyFromLocal URI
hdfs dfs -copyFromLocal input/docs/data2.txt hdfs://localhost/user/rosemary/data2.txt

HDFS Commands Part-1of 4

copyToLocal
Works similarly to the get command, except that the destination is restricted to a local file reference.
hdfs dfs -copyToLocal [-ignorecrc] [-crc] URI
hdfs dfs -copyToLocal data2.txt data2.copy.txt

count
Counts the number of directories, files, and bytes under the paths that match the specified file pattern.
hdfs dfs -count [-q]
hdfs dfs -count hdfs://nn1.example.com/file1 hdfs://nn2.example.com/file2

cp
Copies one or more files from a specified source to a specified destination. If you specify multiple sources, the specified destination must be a directory.
hdfs dfs -cp URI [URI …]
hdfs dfs -cp /user/hadoop/file1 /user/hadoop/file2 /user/hadoop/dir

du
Displays the size of the specified file, or the sizes of files and directories that are contained in the specified directory. If you specify the -s option, displays an aggregate summary of file sizes rather than individual file sizes. If you specify the -h option, formats the file sizes in a "human-readable" way.

hdfs dfs -du [-s] [-h] URI [URI …]
hdfs dfs -du /user/hadoop/dir1 /user/hadoo

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