HDFS 的Shell操作
- 基本语法
bin/hadoop fs 具体命令 OR bin/hadoop dfs 具体命令
dfs是fs的现实类
2. 命令总结
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] <localsrc> ... <dst>]
[-copyToLocal [-f] [-p] [-ignoreCrc] [-crc] <src> ... <localdst>]
[-count [-q] [-h] [-v] [-t [<storage type>]] [-u] [-x] <path> ...]
[-cp [-f] [-p | -p[topax]] [-d] <src> ... <dst>]
[-createSnapshot <snapshotDir> [<snapshotName>]]
[-deleteSnapshot <snapshotDir> <snapshotName>]
[-df [-h] [<path> ...]]
[-du [-s] [-h] [-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] [<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 ...]]
- 具体命令实操
(1)启动Hadoop集群
[root@bigdata111 hadoop-2.8.4]# sbin/start-dfs.sh
[root@bigdata111 hadoop-2.8.4]# sbin/start-yarn.sh
(2)-help :输出这个命令参数
[root@bigdata111 hadoop-2.8.4]# hadoop fs -help rm
-rm [-f] [-r|-R] [-skipTrash] [-safely] <src> ... :
Delete all files that match the specified file pattern. Equivalent to the Unix
command "rm <src>"
-f If the file does not exist, do not display a diagnostic message or
modify the exit status to reflect an error.
-[rR] Recursively deletes directories.
-skipTrash option bypasses trash, if enabled, and immediately deletes <src>.
-safely option requires safety confirmation, if enabled, requires
confirmation before deleting large directory with more than
<hadoop.shell.delete.limit.num.files> files. Delay is expected when
walking over large directory recursively to count the number of
files to be deleted before the confirmation.
(3)-ls:显示目录信息
[root@bigdata111 hadoop-2.8.4]# hadoop fs -ls/
(4)-moveFromLocal:从本地剪切粘贴到hdfs
[root@bigdata111 hadoop-2.8.4]# touch test.txt
[root@bigdata111 hadoop-2.8.4]# hadoop fs -moveFromLocal ./test.txt / software
(5)-appendToFile:追加一个文件到存在文件的末尾
[root@bigdata111 hadoop-2.8.4]# touch test1.txt
[root@bigdata111 hadoop-2.8.4]# hadoop fs -appendToFile test1.txt opt/software/test.txt
(6)-cat :显示文件内容
[root@bigdata111 hadoop-2.8.4]# hadoop fs -cat opt/sofeware/test1.txt
(7)-copyFromLocal(put):从本地系统拷贝文件到hdfs中去
[root@bigdata111 hadoop-2.8.4]# hadoop fs -copyFromLocal test.txt /
(8) -copyToLocal (get):从HDFS拷贝到本地
[root@bigdata111 hadoop-2.8.4]# hadoop fs -copyToLocal opt/software/test.txt
(9)-setrep 设置HDFS中文件的副本数量
[root@bigdata111 hadoop-2.8.4]# hadoop fs -setrep 副本数 opt/software/test.txt
这里设置的副本数只记录在NameNode 的元数据中,否则真的会有这么多副本,还得看NameNode数量,如果是3台设备,最多3个副本,只有节点数增加到10时,副本数才能达到10。
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