HDFS文件命令

HDFS在设计上仿照Linux下的文件操作命令，所以对熟悉Linux文件命令的小伙伴很好上手。另外在Hadoop DFS中没有pwd概念，所有都需要全路径。（本文基于版本2.5 CDH 5.2.1）
列出命令列表、格式和帮助,以及选择一个非参数文件配置的namenode。

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-df [-h] [path …] :
Shows the capacity, free and used space of the filesystem. If the filesystem has
multiple partitions, and no path to a particular partition is specified, then
the status of the root partitions will be shown.

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-mkdir [-p] path … :
Create a directory in specified location.

-p Do not fail if the directory already exists

-rmdir dir … :
Removes the directory entry specified by each directory argument, provided it is
empty.

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-copyFromLocal [-f] [-p] localsrc … dst :
Identical to the -put command.

-copyToLocal [-p] [-ignoreCrc] [-crc] src … localdst :
Identical to the -get command.

-moveFromLocal localsrc …

——————————————————————————– -ls [-d] [-h] [-R] [path …] : List the contents that match the specified file pattern. If path is not specified, the contents of /user/currentUser will be listed. Directory entries are of the form: permissions – userId groupId sizeOfDirectory(in bytes) modificationDate(yyyy-MM-dd HH:mm) directoryName and file entries are of the form: permissions numberOfReplicas userId groupId sizeOfFile(in bytes) modificationDate(yyyy-MM-dd HH:mm) fileName -d Directories are listed as plain files. -h Formats the sizes of files in a human-readable fashion rather than a number of bytes. -R Recursively list the contents of directories.

——————————————————————————– -checksum src … : Dump checksum information for files that match the file pattern src to stdout. Note that this requires a round-trip to a datanode storing each block of the file, and thus is not efficient to run on a large number of files. The checksum of a file depends on its content, block size and the checksum algorithm and parameters used for creating the file.

——————————————————————————– -appendToFile localsrc … dst : Appends the contents of all the given local files to the given dst file. The dst file will be created if it does not exist. If localSrc is -, then the input is read from stdin.

——————————————————————————– -tail [-f] file : Show the last 1KB of the file.

——————————————————————————– -cp [-f] [-p | -p[topax]] src …

——————————————————————————– -count [-q] path … : Count the number of directories, files and bytes under the paths that match the specified file pattern. The output columns are: DIR_COUNT FILE_COUNT CONTENT_SIZE FILE_NAME or QUOTA REMAINING_QUOTA SPACE_QUOTA REMAINING_SPACE_QUOTA DIR_COUNT FILE_COUNT CONTENT_SIZE FILE_NAME -du [-s] [-h] path … : Show the amount of space, in bytes, used by the files that match the specified file pattern. The following flags are optional: -s Rather than showing the size of each individual file that matches the pattern, shows the total (summary) size. -h Formats the sizes of files in a human-readable fashion rather than a number of bytes. Note that, even without the -s option, this only shows size summaries one level deep into a directory. The output is in the form size name(full path)

——————————————————————————– -chgrp [-R] GROUP PATH… : This is equivalent to -chown … :GROUP … -chmod [-R] MODE[,MODE]… | OCTALMODE PATH… : Changes permissions of a file. This works similar to the shell’s chmod command with a few exceptions. -R modifies the files recursively. This is the only option currently supported. MODE Mode is the same as mode used for the shell’s command. The only letters recognized are ‘rwxXt’, e.g. +t,a+r,g-w,+rwx,o=r. OCTALMODE Mode specifed in 3 or 4 digits. If 4 digits, the first may be 1 or 0 to turn the sticky bit on or off, respectively. Unlike the shell command, it is not possible to specify only part of the mode, e.g. 754 is same as u=rwx,g=rx,o=r. If none of ‘augo’ is specified, ‘a’ is assumed and unlike the shell command, no umask is applied. -chown [-R] [OWNER][:[GROUP]] PATH… : Changes owner and group of a file. This is similar to the shell’s chown command with a few exceptions. -R modifies the files recursively. This is the only option currently supported. If only the owner or group is specified, then only the owner or group is modified. The owner and group names may only consist of digits, alphabet, and any of [-_./@a-zA-Z0-9]. The names are case sensitive. WARNING: Avoid using ‘.’ to separate user name and group though Linux allows it. If user names have dots in them and you are using local file system, you might see surprising results since the shell command ‘chown’ is used for local files. -touchz path … : Creates a file of zero length at path with current time as the timestamp of that path. An error is returned if the file exists with non-zero length

——————————————————————————– -test -[defsz] path : Answer various questions about path, with result via exit status. -d return 0 if path is a directory. -e return 0 if path exists. -f return 0 if path is a file. -s return 0 if file path is greater than zero bytes in size. -z return 0 if file path is zero bytes in size, else return 1.

——————————————————————————– -setrep [-R] [-w] rep path … : Set the replication level of a file. If path is a directory then the command recursively changes the replication factor of all files under the directory tree rooted at path. -w It requests that the command waits for the replication to complete. This can potentially take a very long time.