How does a Single file get stored in HDFS

Here is a neat diagram showing how file is split and stored in HDFS

MapReduce Architecture !

Hello,

I feel better than reading books, Images speaks louder !!
Just have a complete look and then study from Hadoop Definitive Guide.

Hadoop Basic Commands

Hadoop Commands
No	Command	Command Usage	Description
1	cat	hadoop dfs -cat <path>	prints the file contents
2	chgrp	hadoop dfs -chgrp [-R] GROUP URI [URI …]	Change group association of files. With -R, make the change recursively through the directory structure. The user must be the owner of files, or else a super-user.
3	chmod	hadoop dfs -chmod [-R] <MODE[,MODE]... | OCTALMODE> URI
4	chown	hadoop dfs -chown [-R] [OWNER][:[GROUP]] URI [URI ]
5	copyFromLocal	hadoop dfs -copyFromLocal <localsrc> URI
6	copyToLocal	hadoop dfs -copyToLocal [-ignorecrc] [-crc] URI
7	count	hadoop dfs -count [-q] <paths>
8	cp	hadoop dfs -cp URI [URI …] <dest>
9	du	hadoop dfs -du URI [URI …]	Get size of each file in dir
10	dus	hadoop dfs -dus URI [URI …]	Gets total file size
11	expunge	hadoop dfs -expunge	Empty the Trash
12	get	hadoop dfs -get [-ignorecrc] [-crc] <src> <localdst>
13	getmerge	hadoop dfs -getmerge <src> <localdst> [addnl]	Takes a source directory and a destination file as input and concatenates files in src into the destination local file. Optionally addnl can be set to enable adding a newline character at the end of each file
14	ls	hadoop dfs -ls path
15	lsr	hadoop dfs -lsr <args>	Recursive version of ls. Similar to Unix ls -R
16	mkdir
17	moveFromLocal
18	moveToLocal
19	mv
20	put
21	rm
22	rmr	hadoop dfs -rmr [-skipTrash] URI [URI …]
23	setrep	hadoop dfs -setrep [-R] <path>	Changes the replication factor of a file. -R option is for recursively increasing the replication factor of files within a directory.
24	stat	hadoop dfs -stat URI [URI …]
25	tail	hadoop dfs -tail [-f] URI	Displays last kilobyte of the file to stdout. -f option can be used as in Unix
26	test	hadoop dfs -test -[ezd] URI	e check to see if the file exists. Return 0 if true. z check to see if the file is zero length. Return 0 if true. -d check to see if the path is directory. Return 0 if true
27	text	hadoop dfs -text <src>	Takes a source file and outputs the file in text format
28	touchz	hadoop dfs -touchz URI [URI …]	Create a file of zero length.
29	jar	hadoop jar	The hadoop jar command runs a JAR file.
30	fsck	hadoop fsck	HDFS supports the fsck command to check for various inconsistencies. It it is designed for reporting problems with various files, for example, missing blocks for a file or under-replicated blocks.
31	job	hadoop job -list

Basic Linux Commands

Commands in linux
Command	Meaning
ls	Will list the items in files
ll	Will list the items vertically
cat	Will help to read the file mentioned in command.
cd ..	Will one directory back
diff	print line difference in files. Not the entire string
grep	grep 'abc ' /chitrank/txt . Search abc text in txt files
grep -v	grep -v 'abc' /chitrank/txt . Not condition of above grep
grep -i	ingnore case
grep -w	to search on given word
cat /chitrank/input/*  | grep -i 'a'	Grep commands with pipe
cat /chitrank/input/*  | grep -l 'a'	to list the file with given word
grep --color 'a'	Will show matches in color
mkdir	will make directory
cd /folder/file	will move to that file directory
awk	find or replace text
chmod	change the access of files or directory // fullacess chmod ug+rwx file.txt  // revoke chmod g-rwx file.txt // give access chmod -R ug+rwx file.txt
chown	change user and group ownership
adduser	add a new user
echo	display message on console
cnp	comapre two files
mv	move file
passwd	modify user password
pwd	print working dir
tar	to
useradd	add new user account
nano	to open editor and make files
sort	to sort file
unzip	unzip a flie
top	find the programs running
kill	kill a task
man	diplays main page
tail	print last lines in file
less	prints less number of outputs
su	switch to other user. Root can switch widout password
yum	to install apche using yum
rpm	to install apche using rpm
date	prints date
get	get file from other loc
put	put file to other loc
find	find files using file name
ssh	remote accesss
cut	cut some part from files
tr	replaces some pattern and changes file output format // tr -s '|' ',' < Ret_MediaTP | cut -f1-28 -d, > MediaTp__Ret.txt
	To find File name
	find . -type f -printf "%f\n" > /home/hduser1/chitrank/freshseq