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4 Layers of AWS Architecture a Quick Answer

I have collected real interview questions on AWS key architecture components. Those are S3, EC2, SQS, and SimpleDB. AWS is one of the most popular skills in the area of Cloud computing. Many companies are recruiting software developers to work on cloud computing.

AWS Key Architecture Components AWS is the top cloud platform. The knowledge of this helpful to learn other cloud platforms. Below are the questions asked in interviews recently.
What are the components involved in AWS?Amazon S3.With this, one can retrieve the key information which is occupied in creating cloud structural design, and the amount of produced information also can be stored in this component that is the consequence of the key specified.Amazon EC2. Helpful to run a large distributed system on the Hadoop cluster. Automatic parallelization and job scheduling can be achieved by this component.Amazon SQS. This component acts as a mediator between different controllers. Also worn for cushioning requirements those are obt…

Hadoop fs (File System) Commands List

List of basic Hadoop hdfs fs File system commands given in this post. These are handy commands. If you remember then you can save lot of time working on Hadoop hdfs.

Hadoop fs (File System) Commands List

The Syntax for Command and the List and Usage.

Hadoop fs -cmd <args>

👉 cmd is a specific command and arg is the variable name. 


Hadoop fs –cat FILE [FILE …]

👉 Displays the files' content. For reading compressed files.


Hadoop fs –chgrp [-R] GROUP PATH [PATH …]

👉 Changes the group association for files and directories. The – R option applies the change recursively. The user must be the files' owner or a superuser.


Hadoop fs –chmod [-R] MODE[,MODE …] PATH [PATH …]

👉 Changes the permissions of files and directories. Like, its Unix equivalent, MODE can be a 3-digit octal mode, or {augo}+/-{rwxX}. The -R option applies the change recursively. The user must be the files' owner or a superuser.


Hadoop fs –chown [-R] [OWNER][:[GROUP]] PATH [PATH…] 

👉 Changes the ownership of files and directories. The –R option applies the change recursively. The user must be a superuser.


Hadoop fs –copyFromLocal LOCALSRC [LOCALSRC …] DST

👉 Identical to put (copy files from the local file system).


Hadoop fs –copyToLocal [-ignorecrc] [-crc] SRC [SRC…] LOCALDST

👉 Identical to get (copy files to the local file system).


Hadoop fs –count [-q] PATH [PATH …]

👉 Displays the number of subdirectories, number of files, number of bytes used, and name for all files/directories identified by PATH. The -qoption displays quota information.


Hadoop fs –cp SRC [SRC …] DST

👉 Copies files from source to destination. If multiple source files are specified, destination must be a directory .


Hadoop fs –du PATH [PATH …]

👉 Displays file sizes. If PATH is a directory, the size of each file in the directory is reported. Filenames are stated with the full URI protocol prefix. Note that although dust and for disk usage, it should not be taken literally, as disk usage depends on block size and replica factors.



Hadoop fs –dus PATH [PATH …]

👉 Like du, but for a directory, dus reports the sum of file sizes in aggregate rather than individually.


Hadoop fs –expunge

👉 Empties the trash. If the trash feature is enabled, when a file is deleted, it is first moved into the temporary. Trash/ folder. The file will be permanently deleted from the. Trash/ folder only after a user-configurable delay. The expunge command forcefully deletes all files from the. Trash/ folder. Note that as long as a file is in the. Trash/ folder, it can be restored by moving it back to its original location.


Hadoop fs –get [-ignorecrc] [-crc] SRC [SRC …] LOCALDST

👉 Copies files to the local filesystem. If multiple source files are specified, a local destination must be a directory. If LOCALDST is -, the files are copied to stdout.

HDFS computes a checksum for each block of each file. The checksums for a file are stored separately in a hidden file. When a file is read from HDFS, the checksums in that hidden file are used to verify the file's integrity. For the get command, the -crc option will copy that hidden checksum file. The - ignore crc option will skip the checksum checking when copying.


Hadoop fs –getmerge SRC [SRC …] LOCALDST [addnl]

👉 Retrieves all files identified by SRC, merges them, and writes the single merged file to LOCALDST in the local filesystem. The option addnl will add a newline character to the end of each file.


Hadoop fs –help [CMD]

👉 Displays usage information for the command CMD. If CMD is omitted, it displays useful information for all commands.


Hadoop fs –ls PATH [PATH …]

👉 Lists files and directories. Each entry shows name, permissions, owner, group, size, and modification date. File entries also show their replication factor.


Hadoop fs –lsr PATH [PATH …]

👉 Recursive version of ls.


Hadoop fs –mkdir PATH [PATH …]

👉 Creates directories. Any missing parent directories are also created (like Unix mkdir –p).


Hadoop fs –moveFromLocal LOCALSRC [LOCALSRC …] DST

👉 Similar to put, except the local source is deleted after it's been successfully copied to HDFS.


Hadoop fs –moveToLocal [-crc] SRC [SRC …] LOCALDST

Displays a "not implemented yet" message.


Hadoop fs –mv SRC [SRC …] DST

👉 Moves files from source(s) to destination. If multiple source files are specified, destination has to be a directory. Moving across filesystems is not permitted.


Hadoop fs –put LOCALSRC [LOCALSRC …] DST

👉 Copies files or directories from local system to destination filesystem. If LOCALSRC is set to -, input is set to stdin and DST must be a file.


Hadoop fs –rm PATH [PATH …]

👉 Deletes files and empty directories.


Hadoop fs –rmr PATH [PATH …]

vRecursive version of rm.


Hadoop fs –setrep [-R] [-w] REP PATH [PATH …]

👉 Sets the target replication factor to REP for given files. The -R option will recursively apply the target replication factor to files in directories identified by PATH. The replication factor will take some time to get to the target. The -w option will wait for the replication factor to match the target.


Hadoop fs –stat [FORMAT] PATH [PATH …]

👉 Displays "statistical" information on files. The FORMAT string is printed exactly but with the following format, specifiers replaced. %b Size of file in blocks %F. The string "directory" or "regular file" depending on file type %n Filename %o Block size %r Replication %y UTC date in yyyy-MM-dd HH:mm:ss format %Y Milliseconds since January 1, 1970 UTC


Hadoop fs –tail [-f] FILE

👉 Displays the last one kilobyte of FILE.


Hadoop fs –test –[ezd] PATH 

👉 Performs one of the following type checks on PATH: -e PATH existence. Returns 0 if PATH exists. -z Empty file. Returns 0 if file length is 0. -d Returns 0 if PATH is a directory.


Hadoop fs –text FILE [FILE …]

👉 Displays the textual content of files. Identical to catif files are text files. Files in known compressed format (gzip and Hadoop's binary sequence file format) are uncompressed first.


Hadoop fs –touchz FILE [FILE …]

👉 Creates files of length 0. Fails if files already exist and have nonzero length.


  1. I feel very grateful that I read this. It is very helpful and very informative and I really learned a lot from it.
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