Hadoop 简明教程

Hadoop - Command Reference

在 "$HADOOP_HOME/bin/hadoop fs" 中还有更多命令未在此处演示，尽管这些基本操作将帮助您入门。不带任何附加参数运行 ./bin/hadoop dfs 将列出 FsShell 系统可以运行的所有命令。此外，如果您遇到困难，*$HADOOP_HOME/bin/hadoop fs -help * commandName 命令将显示有关所讨论操作的简短使用方法摘要。

There are many more commands in "$HADOOP_HOME/bin/hadoop fs" than are demonstrated here, although these basic operations will get you started. Running ./bin/hadoop dfs with no additional arguments will list all the commands that can be run with the FsShell system. Furthermore, *$HADOOP_HOME/bin/hadoop fs -help * commandName will display a short usage summary for the operation in question, if you are stuck.

所有操作的表格如下所示。针对参数使用了以下约定 -

A table of all the operations is shown below. The following conventions are used for parameters −

"<path>" means any file or directory name.
"<path>..." means one or more file or directory names.
"<file>" means any filename.
"<src>" and "<dest>" are path names in a directed operation.
"<localSrc>" and "<localDest>" are paths as above, but on the local file system.

所有其他文件和路径名称指的是 HDFS 内的对象。

All other files and path names refer to the objects inside HDFS.

Sr.No	Command & Description
1	-ls <path> Lists the contents of the directory specified by path, showing the names, permissions, owner, size and modification date for each entry.
2	-lsr <path> Behaves like -ls, but recursively displays entries in all subdirectories of path.
3	-du <path> Shows disk usage, in bytes, for all the files which match path; filenames are reported with the full HDFS protocol prefix.
4	-dus <path> Like -du, but prints a summary of disk usage of all files/directories in the path.
5	-mv <src><dest> Moves the file or directory indicated by src to dest, within HDFS.
6	-cp <src> <dest> Copies the file or directory identified by src to dest, within HDFS.
7	-rm <path> Removes the file or empty directory identified by path.
8	-rmr <path> Removes the file or directory identified by path. Recursively deletes any child entries (i.e., files or subdirectories of path).
9	-put <localSrc> <dest> Copies the file or directory from the local file system identified by localSrc to dest within the DFS.
10	-copyFromLocal <localSrc> <dest> Identical to -put
11	-moveFromLocal <localSrc> <dest> Copies the file or directory from the local file system identified by localSrc to dest within HDFS, and then deletes the local copy on success.
12	-get [-crc] <src> <localDest> Copies the file or directory in HDFS identified by src to the local file system path identified by localDest.
13	-getmerge <src> <localDest> Retrieves all files that match the path src in HDFS, and copies them to a single, merged file in the local file system identified by localDest.
14	-cat <filen-ame> Displays the contents of filename on stdout.
15	-copyToLocal <src> <localDest> Identical to -get
16	-moveToLocal <src> <localDest> Works like -get, but deletes the HDFS copy on success.
17	-mkdir <path> Creates a directory named path in HDFS. Creates any parent directories in path that are missing (e.g., mkdir -p in Linux).
18	-setrep [-R] [-w] rep <path> Sets the target replication factor for files identified by path to rep. (The actual replication factor will move toward the target over time)
19	-touchz <path> Creates a file at path containing the current time as a timestamp. Fails if a file already exists at path, unless the file is already size 0.
20	-test -[ezd] <path> Returns 1 if path exists; has zero length; or is a directory or 0 otherwise.
21	-stat [format] <path> Prints information about path. Format is a string which accepts file size in blocks (%b), filename (%n), block size (%o), replication (%r), and modification date (%y, %Y).
22	-tail [-f] <file2name> Shows the last 1KB of file on stdout.
23	-chmod [-R] mode,mode,… <path>… Changes the file permissions associated with one or more objects identified by path…. Performs changes recursively with R. mode is a 3-digit octal mode, or {augo}+/-{rwxX}. Assumes if no scope is specified and does not apply an umask.
24	-chown [-R] [owner][:[group]] <path>… Sets the owning user and/or group for files or directories identified by path…. Sets owner recursively if -R is specified.
25	-chgrp [-R] group <path>… Sets the owning group for files or directories identified by path…. Sets group recursively if -R is specified.
26	-help <cmd-name> Returns usage information for one of the commands listed above. You must omit the leading '-' character in cmd.