lite-log hadoop hdfs

Copy Files from Hadoop HDFS to Local

94 views 0 comments about 5 months ago Raymond Tang

Copy file from HDFS to local

Use the following command:

hadoop fs [-copyToLocal [-f] [-p] [-ignoreCrc] [-crc] <src> ... <localdst>]

For example, copy a file from /hdfs-file.txt in HDFS to local /tmp/ using the following command:

hadoop fs -copyToLocal /hdfs-file.txt /tmp/hdfs-file.txt

HDFS CLI

If you forgot any HDFS commands, you can use the following command to list all of them:

hadoop fs

The output will generate all the commands (not all of them are implemented yet):

hadoop fs
Usage: hadoop fs [generic options]
         [-appendToFile <localsrc> ... <dst>]
         [-cat [-ignoreCrc] <src> ...]
         [-checksum <src> ...]
         [-chgrp [-R] GROUP PATH...]
         [-chmod [-R] <MODE[,MODE]... | OCTALMODE> PATH...]
         [-chown [-R] [OWNER][:[GROUP]] PATH...]
         [-copyFromLocal [-f] [-p] [-l] [-d] [-t <thread count>] <localsrc> ... <dst>]
         [-copyToLocal [-f] [-p] [-ignoreCrc] [-crc] <src> ... <localdst>]
         [-count [-q] [-h] [-v] [-t [<storage type>]] [-u] [-x] [-e] <path> ...]
         [-cp [-f] [-p | -p[topax]] [-d] <src> ... <dst>]
         [-createSnapshot <snapshotDir> [<snapshotName>]]
         [-deleteSnapshot <snapshotDir> <snapshotName>]
         [-df [-h] [<path> ...]]
         [-du [-s] [-h] [-v] [-x] <path> ...]
         [-expunge]
         [-find <path> ... <expression> ...]
         [-get [-f] [-p] [-ignoreCrc] [-crc] <src> ... <localdst>]
         [-getfacl [-R] <path>]
         [-getfattr [-R] {-n name | -d} [-e en] <path>]
         [-getmerge [-nl] [-skip-empty-file] <src> <localdst>]
         [-help [cmd ...]]
         [-ls [-C] [-d] [-h] [-q] [-R] [-t] [-S] [-r] [-u] [-e] [<path> ...]]
         [-mkdir [-p] <path> ...]
         [-moveFromLocal <localsrc> ... <dst>]
         [-moveToLocal <src> <localdst>]
         [-mv <src> ... <dst>]
         [-put [-f] [-p] [-l] [-d] <localsrc> ... <dst>]
         [-renameSnapshot <snapshotDir> <oldName> <newName>]
         [-rm [-f] [-r|-R] [-skipTrash] [-safely] <src> ...]
         [-rmdir [--ignore-fail-on-non-empty] <dir> ...]
         [-setfacl [-R] [{-b|-k} {-m|-x <acl_spec>} <path>]|[--set <acl_spec> <path>]]
         [-setfattr {-n name [-v value] | -x name} <path>]
         [-setrep [-R] [-w] <rep> <path> ...]
         [-stat [format] <path> ...]
         [-tail [-f] <file>]
         [-test -[defsz] <path>]
         [-text [-ignoreCrc] <src> ...]
         [-touchz <path> ...]
         [-truncate [-w] <length> <path> ...]
         [-usage [cmd ...]]

Generic options supported are:
-conf <configuration file>        specify an application configuration file
-D <property=value>               define a value for a given property
-fs <file:///|hdfs://namenode:port> specify default filesystem URL to use, overrides 'fs.defaultFS' property from configurations.
-jt <local|resourcemanager:port>  specify a ResourceManager
-files <file1,...>                specify a comma-separated list of files to be copied to the map reduce cluster
-libjars <jar1,...>               specify a comma-separated list of jar files to be included in the classpath
-archives <archive1,...>          specify a comma-separated list of archives to be unarchived on the compute machines

The general command line syntax is:
command [genericOptions] [commandOptions]

If you want to view the detailed syntax for any command, you can try the following command:

hadoop fs -help [command]

For example, run command ‘hadoop fs -help copyToLocal’ will generate the following output:

hadoop fs -help copyToLocal
-copyToLocal [-f] [-p] [-ignoreCrc] [-crc] <src> ... <localdst> :
   Identical to the -get command.

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