hdfs commands

Sudo addgroup hadoop # Add a hadoop GroupSudo usermod-a-g hadoop Larry # Add the current user to the hadoop GroupSudo gedit ETC/sudoers # Add the hadoop group to sudoerHadoop all = (all) All after root all = (all) All Modify hadoop Directory PermissionsSudo chown-r Larry: hadoop/home/Larry/hadoop Sudo chmod-r 755/home/Larry/hadoop Modify HDFS PermissionsSudo bin/hadoop DFS-chmod-r 755/Sudo bin/hadoop DFS-ls/ Modify the

Add a Hadoop group sudo addgroup Hadoop Add the current user Larry to the Hadoop groupsudo usermod-a-G Hadoop Larry Add Hadoop Group to Sudoersudo gedit etc/sudoersHadoop all= (All) after Root all= (all) Modify the permissions for the Hadoop directorysudo chown-r larry:hadoop/home/larry/hadoop Modify permissions for HDFssudo chmod-r 755/home/larry/hadoopsudo bin/hadoop dfs-chmod-r 755/sudo bin/hadoop dfs-ls/ Modify the owner of the HDFs filesudo bin/

Common HDFS file operation commands and precautions The HDFS file system provides a considerable number of shell operation commands, which greatly facilitates programmers and system administrators to view and modify files on HDFS. Furthermore,

Namenode large amount of memory; Seek time exceeds read time;Concurrent write, File random modification: A file can only have one writer; only support appendIv. HDFs ArchitectureMaster Master(only one): can be used to manage HDFs namespaces, manage block mapping information, configure replica policies, handle client read and write requests NameNode : Fsimage and fsedits can be combined regularly, pushed

hdfs:/-cp/test.txt/test2.txt5. Move the file MVHadoop fs-mv hdfs:/test.txt hdfs:/dir/test.txt Hadoop fs-mv/test.txt/dir/test.txt6. Delete files/directories RM 6.1 Deleting the specified file Hadoop fs-rm/a.txt 6.2 Delete all txt files /* . txt 6.3 Recursively delete all files and directories Hadoop fs-rm-r/dir/7. Read the file

HDFs Common commands:Note: The following execution commands are in the bin directory of the Spark installation directory.Path src for file path dist to folder1.-help[cmd] Show Help for commands ./hdfs Dfs-help ls 2.-ls (r) displays all files in the current directory-R layer-by-layer follow-up folder ./

Hadoop FS: Use the widest range of surfaces to manipulate any file system.Hadoop DFS and HDFs DFS: can only operate on HDFs file system-related (including operations with local FS), which is already deprecated, typically using the latter.The following reference is from StackOverflowFollowing is the three commands which appears same but has minute differences

Hadoop FS: Use the widest range of surfaces to manipulate any file system.Hadoop DFS and HDFs DFS: can only operate on HDFs file system-related (including operations with local FS), which is already deprecated, typically using the latter.The following reference is from StackOverflowFollowing is the three commands which appears same but has minute differences

From:http://www.2cto.com/database/201303/198460.htmlHadoop HDFs Common CommandsHadoop common commands:Hadoop FSView all commands supported by Hadoop HDFsHadoop fs–lslisting directory and file informationHadoop FS–LSRLoop lists directories, subdirectories, and file informationHadoop fs–put Test.txt/user/sunlightcsCopy the test.txt of the local file system to the/user/sunlightcs directory of the

under the directory, the X permission indicates that the sub-directory can be accessed from this directory. Unlike the POSIX model, HDFS does not contain sticky, setuid, and setgid. HDFS is designed to process massive data, that is, it can store a large number of files (Tb-level files) on it. After HDFS splits these files, it is stored on different datanode

, soHDFs has a high degree of fault tolerance.3. High data throughput HDFs uses a "one-time write, multiple read" This simple data consistency model, in HDFS , once a file has been created, written, closed, generally do not need to modify, such a simple consistency model, to improve throughput.4. Streaming data access HDFS has a large scale of data processing,

[cmd ...]Management commands for HDFs[Email protected] hadoop-2.7.3]$ bin/HDFs Dfsadminusage:hdfs dfsadminnote:administrative commands can only be run as the HDFs Superuser. [-report [-live] [-dead] [-Decommissioning]] [-safemode ] [-Savenamespace] [-Rolledits] [-restore

1. The command format for HDFS operations is1.1hadoop fs-ls1.2 Hadoop fs-lsr1.3hadoop fs-mkdir1.4hadoop fs-put1.5hadoop fs-get1.6hadoop fs-text1.7hadoop fs-rm1.8hadoop fs-rmr2.hdfs when a block partition of data storage, if the file size exceeds block, then according to block size partition, rather than block sizes, divided into a block, is the actual data size.Permissiondenyexception Insufficient Permissio

Hadoop fs-mkdir/tmp/input new folder on HDFs Hadoop fs-put input1.txt/tmp/input The local file input1.txt to the/tmp/input directory in HDFs Hadoop fs-get input1.txt/tmp/input/input1.txt to pull HDFs files to localHadoop fs-ls/tmp/output lists a directory for HDFsHadoop fs-cat/tmp/ouput/output1.txt viewing files on HDFs