Chapter 2 shell operation of hfds

2.1 Basic grammar

hadoop fs  Specific commands 

or

hdfs dfs  Specific commands 

2.2 The command of

The specific command is as follows

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] <localsrc> ... <dst>]
	[-copyToLocal [-p] [-ignoreCrc] [-crc] <src> ... <localdst>]
	[-count [-q] [-h] [-v] [-x] <path> ...]
	[-cp [-f] [-p | -p[topax]] <src> ... <dst>]
	[-createSnapshot <snapshotDir> [<snapshotName>]]
	[-deleteSnapshot <snapshotDir> <snapshotName>]
	[-df [-h] [<path> ...]]
	[-du [-s] [-h] [-x] <path> ...]
	[-expunge]
	[-find <path> ... <expression> ...]
	[-get [-p] [-ignoreCrc] [-crc] <src> ... <localdst>]
	[-getfacl [-R] <path>]
	[-getfattr [-R] {
    -n name | -d} [-e en] <path>]
	[-getmerge [-nl] <src> <localdst>]
	[-help [cmd ...]]
	[-ls [-C] [-d] [-h] [-q] [-R] [-t] [-S] [-r] [-u] [<path> ...]]
	[-mkdir [-p] <path> ...]
	[-moveFromLocal <localsrc> ... <dst>]
	[-moveToLocal <src> <localdst>]
	[-mv <src> ... <dst>]
	[-put [-f] [-p] [-l] <localsrc> ... <dst>]
	[-renameSnapshot <snapshotDir> <oldName> <newName>]
	[-rm [-f] [-r|-R] [-skipTrash] <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> ...]
	[-usage [cmd ...]]

Generic options supported are
-conf <configuration file>     specify an application configuration file
-D <property=value>            use value for given property
-fs <local|namenode:port>      specify a namenode
-jt <local|resourcemanager:port>    specify a ResourceManager
-files <comma separated list of files>    specify comma separated files to be copied to the map reduce cluster
-libjars <comma separated list of jars>    specify comma separated jar files to include in the classpath.
-archives <comma separated list of archives>    specify comma separated archives to be unarchived on the compute machines.

The general command line syntax is
bin/hadoop command [genericOptions] [commandOptions]

2.3 Common commands

Be careful ： If you are prompted root Permission cannot write , Please switch to hdfs The user action

2.3.1 -help

Help order

hadoop fs -help rm

or

hdfs dfs -help rm

Be careful ：hadoop Script 、hdfs Script , stay hadoop Installation directory bin Under the table of contents

2.3.2 -ls

Display directory information

hadoop fs -ls /

or

hdfs dfs –ls /

2.3.3 -mkdir

stay hdfs Create directory on

hadoop fs -mkdir -p /teaching/hdfs

or

hdfs dfs -mkdir -p /teaching/hdfs

2.3.4 -moveFromLocal

Cut and paste from local to hdfs

touch test.txt
hadoop fs  -moveFromLocal  ./test.txt  /teaching/hdfs

or

hdfs dfs –moveFromLocal ./test.txt /teaching/hdfs

Be careful ： The execution process is to copy , Delete after , If hdfs If the user does not have permission to delete local files, copy to hdfs To succeed , Deleting local files cannot succeed

2.3.5 -appendToFile

Appends a file to the end of an existing file

touch test2.txt
vi test2.txt
#  Input 
hello hdfs

hadoop fs -appendToFile test2.txt /teaching/hdfs/test.txt

or

hdfds dfs -appendToFile test2.txt /teaching/hdfs/test.txt

2.3.6 -cat

View file contents

hadoop fs -cat /teaching/hdfs/test.txt

or

hdfs dfs –cat /teaching/hdfs/test.txt

2.3.7 -tail

Show file last 1kb Content

hadoop fs -tail /teaching/hdfs/test.txt

or

hdfs dfs -tail /teaching/hdfs/test.txt

2.3.8 -chgrp、-chmod、-chown

Modify the group to which the file belongs 、 jurisdiction 、 user

1. modify HDFS Stored files /teaching/hdfs/tt.txt File group , Default group ：supergroup Options -R Recursive execution

$ hdfs dfs -ls /teaching/hdfs
-rw-r--r--   3 hdfs supergroup         11 2019-08-12 14:40 /teaching/hdfs/tt.txt
$ hdfs dfs -chgrp lubin-group /teaching/hdfs/tt.txt
$ hdfs dfs -ls /teaching/hdfs
-rw-r--r--   3 hdfs lubin-group         11 2019-08-12 14:40 /teaching/hdfs/tt.txt

2. modify HDFS Stored files /teaching/hdfs/tt.txt File permissions

$ hdfs dfs -chmod 666 /teaching/hdfs/tt.txt
$ hdfs dfs -ls /teaching/hdfs
-rw-rw-rw-   3 hdfs lubin-group         11 2019-08-12 14:40 /teaching/hdfs/tt.txt

3. modify HDFS Stored files /teaching/hdfs/tt.txt Users and groups to which the file belongs ,lubin1 For the user ,lubin2 As group

$ hdfs dfs -chown lubin1:lubin2 /teaching/hdfs/tt.txt
$ hdfs dfs -ls /teaching/hdfs/tt.txt
-rw-rw-rw-   3 lubin1 lubin2         11 2019-08-12 14:40 /teaching/hdfs/tt.txt

2.3.9 -copyFromLocal

Copy files from the local file system to hdfs route

hadoop fs -copyFromLocal README.txt /teaching/hdfs

or

hdfs dfs -copyFromLocal test3.txt /teaching/hdfs

2.3.10 -copyToLocal

from hdfs Copy to local

hadoop fs -copyToLocal /teaching/hdfs/test.txt /tmp

or

hdfs dfs –copyToLocal /teaching/hdfs/test.txt /tmp

2.3.11 -cp

from hdfs Copy a path to hdfs The other path

hadoop fs -cp /teaching/hdfs/test3.txt /teaching/hdfs2

or

hdfs dfs -cp /teaching/hdfs/test3.txt /teaching/hdfs2

2.3.12 -mv

stay hdfs Move files in the directory

hadoop fs -mv /teaching/hdfs/tt.txt /teaching/hdfs2

or

hdfs dfs -mv /teaching/hdfs/tt.txt /teaching/hdfs2

2.3.13 -get

Equate to copyToLocal, from hdfs Download files to local

hadoop fs -get /teaching/hdfs/test3.txt /tmp

or

hdfs dfs -get /teaching/hdfs/test3.txt /tmp

2.3.14 -getmerge

Merge and download multiple files （ The contents of multiple files are merged into one file ）, such as hdfs The catalog of /aaa/ There are multiple files under :log.1, log.2,log.3,…

hadoop fs -getmerge  /teaching/hdfs/log*.txt /tmp/log.txt

or

hdfs dfs -getmerge /teaching/hdfs/log*.txt /tmp/log.txt

2.3.15 -put

Equate to copyFromLocal

hadoop fs -put log1.txt /teaching/hdfs

or

hdfs dfs –put log1.txt /teaching/hdfs

2.3.16 -rm

Delete files or folders

hadoop fs -rm /teaching/hdfs2/log1.txt

or

hdfs dfs –rm /teaching/hdfs2/log2.txt

Be careful ： If the user does not have permission to delete , You can delete ：su hdfs -c “hadoop fs -rm /test/test.txt”

2.3.17 -rmdir

Delete empty directory

hadoop fs -rmdir /test

or

hdfs dfs –rmdir /test

Be careful ： The above command can only delete empty directories , Delete non empty employment rm command

2.3.18 -du

Statistics folder size information

hadoop fs -du -s -h /teaching/hdfs

or

hdfs dfs -du -s -h /teaching/hdfs
58  174  /teaching/hdfs

Be careful ：-s Display total （ Abstract ） size , Get rid of -s Then each matching file size is displayed ;
-h Format the size in a human readable way , Not in bytes ;
The first column shows the total file size under the directory , The second column indicates the total storage size of all files in the directory on the cluster （ Related to the number of copies ）, The third column is the directory name of the query

2.3.19 -setrep

Set up hdfs The number of copies of the file in

hadoop fs -setrep 10 /teaching/hdfs/test.txt

or

hdfs dfs –setrep 2 /teaching/hdfs /test.txt

The number of copies set is only recorded in NameNode In the metadata of , Whether there really will be so many copies , Have to see DataNode The number of . Because there is only 3 device , Most are 3 Copies , If set to 10, Only the number of nodes increases to 10 When the machine , Number of copies 10.