hadoop hdfs dfs 命令讲解
hdfs dfs命令
appendToFile
Usage: hdfs dfs -appendToFile
追加一个或者多个文件到hdfs制定文件中.也可以从命令行读取输入.
· hdfs dfs -appendToFile localfile /user/hadoop/hadoopfile
· hdfs dfs -appendToFile localfile1 localfile2 /user/hadoop/hadoopfile
· hdfs dfs -appendToFile localfile hdfs://nn.example.com/hadoop/hadoopfile
· hdfs dfs -appendToFile - hdfs://nn.example.com/hadoop/hadoopfile Reads the input from stdin.
Exit Code:
Returns 0 on success and 1 on error.
cat
Usage: hdfs dfs -cat URI [URI ...]
查看内容.
Example:
· hdfs dfs -cat hdfs://nn1.example.com/file1 hdfs://nn2.example.com/file2
· hdfs dfs -cat file:///file3 /user/hadoop/file4
Exit Code:
Returns 0 on success and -1 on error.
Chgrp【change group】
Usage: hdfs dfs -chgrp [-R] GROUP URI [URI ...]
修改所属组.
Options
· The -R option will make the change recursively through the directory structure.
chmod
Usage: hdfs dfs -chmod [-R]
修改权限.
Options
· The -R option will make the change recursively through the directory structure.
chown
Usage: hdfs dfs -chown [-R] [OWNER][:[GROUP]] URI [URI ]
修改所有者.
Options
· The -R option will make the change recursively through the directory structure.
copyFromLocal
Usage: hdfs dfs -copyFromLocal
Similar to put command, except that the source is restricted to a local file reference.
Options:
· The -f option will overwrite the destination if it already exists.
copyToLocal
Usage: hdfs dfs -copyToLocal [-ignorecrc] [-crc] URI
Similar to get command, except that the destination is restricted to a local file reference.
count
Usage: hdfs dfs -count [-q] [-h]
列出文件夹数量、文件数量、内容大小. The output columns with -count are: DIR_COUNT, FILE_COUNT, CONTENT_SIZE FILE_NAME
The output columns with -count -q are: QUOTA, REMAINING_QUATA, SPACE_QUOTA, REMAINING_SPACE_QUOTA, DIR_COUNT, FILE_COUNT, CONTENT_SIZE, FILE_NAME
The -h option shows sizes in human readable format.
Example:
· hdfs dfs -count hdfs://nn1.example.com/file1 hdfs://nn2.example.com/file2
· hdfs dfs -count -q hdfs://nn1.example.com/file1
· hdfs dfs -count -q -h hdfs://nn1.example.com/file1
Exit Code:
Returns 0 on success and -1 on error.
cp
Usage: hdfs dfs -cp [-f] [-p | -p[topax]] URI [URI ...]
复制文件(夹)，可以覆盖，可以保留原有权限信息
Options:
· The -f option will overwrite the destination if it already exists.
· The -p option will preserve file attributes [topx] (timestamps, ownership, permission, ACL, XAttr). If -p is specified with no arg, then preserves timestamps, ownership, permission. If -pa is specified, then preserves permission also because ACL is a super-set of permission. Determination of whether raw namespace extended attributes are preserved is independent of the -p flag.
Example:
· hdfs dfs -cp /user/hadoop/file1 /user/hadoop/file2
· hdfs dfs -cp /user/hadoop/file1 /user/hadoop/file2 /user/hadoop/dir
Exit Code:
Returns 0 on success and -1 on error.
du
Usage: hdfs dfs -du [-s] [-h] URI [URI ...]
显示文件(夹)大小.
Options:
· The -s option will result in an aggregate summary of file lengths being displayed, rather than the individual files.
· The -h option will format file sizes in a "human-readable" fashion (e.g 64.0m instead of 67108864)
Example:
· hdfs dfs -du /user/hadoop/dir1 /user/hadoop/file1 hdfs://nn.example.com/user/hadoop/dir1
Exit Code: Returns 0 on success and -1 on error.
dus
Usage: hdfs dfs -dus
Displays a summary of file lengths.
Note: This command is deprecated. Instead use hdfs dfs -du -s.
expunge
Usage: hdfs dfs -expunge
清空回收站.
get
Usage: hdfs dfs -get [-ignorecrc] [-crc]
Copy files to the local file system. Files that fail the CRC check may be copied with the -ignorecrc option. Files and CRCs may be copied using the -crc option.
Example:
· hdfs dfs -get /user/hadoop/file localfile
· hdfs dfs -get hdfs://nn.example.com/user/hadoop/file localfile
Exit Code:
Returns 0 on success and -1 on error.
getfacl
Usage: hdfs dfs -getfacl [-R]
显示权限信息.
Options:
· -R: List the ACLs of all files and directories recursively.
· path: File or directory to list.
Examples:
· hdfs dfs -getfacl /file
· hdfs dfs -getfacl -R /dir
Exit Code:
Returns 0 on success and non-zero on error.
getfattr
Usage: hdfs dfs -getfattr [-R] -n name | -d [-e en]
Displays the extended attribute names and values (if any) for a file or directory.
Options:
· -R: Recursively list the attributes for all files and directories.
· -n name: Dump the named extended attribute value.
· -d: Dump all extended attribute values associated with pathname.
· -e encoding: Encode values after retrieving them. Valid encodings are "text", "hex", and "base64". Values encoded as text strings are enclosed in double quotes ("), and values encoded as hexadecimal and base64 are prefixed with 0x and 0s, respectively.
· path: The file or directory.
Examples:
· hdfs dfs -getfattr -d /file
· hdfs dfs -getfattr -R -n user.myAttr /dir
Exit Code:
Returns 0 on success and non-zero on error.
getmerge
Usage: hdfs dfs -getmerge
合并.
ls
Usage: hdfs dfs -ls [-R]
Options:
· The -R option will return stat recursively through the directory structure.
For a file returns stat on the file with the following format:
permissions number_of_replicas userid groupid filesize modification_date modification_time filename
For a directory it returns list of its direct children as in Unix. A directory is listed as:
permissions userid groupid modification_date modification_time dirname
Example:
· hdfs dfs -ls /user/hadoop/file1
Exit Code:
Returns 0 on success and -1 on error.
lsr
Usage: hdfs dfs -lsr
Recursive version of ls.
Note: This command is deprecated. Instead use hdfs dfs -ls -R
mkdir
Usage: hdfs dfs -mkdir [-p]
Takes path uri's as argument and creates directories.
Options:
· The -p option behavior is much like Unix mkdir -p, creating parent directories along the path.
Example:
· hdfs dfs -mkdir /user/hadoop/dir1 /user/hadoop/dir2
· hdfs dfs -mkdir hdfs://nn1.example.com/user/hadoop/dir hdfs://nn2.example.com/user/hadoop/dir
Exit Code:
Returns 0 on success and -1 on error.
moveFromLocal
Usage: hdfs dfs -moveFromLocal
Similar to put command, except that the source localsrc is deleted after it's copied.
moveToLocal
Usage: hdfs dfs -moveToLocal [-crc]
Displays a "Not implemented yet" message.
mv
Usage: hdfs dfs -mv URI [URI ...]
Moves files from source to destination. This command allows multiple sources as well in which case the destination needs to be a directory. Moving files across file systems is not permitted.
Example:
· hdfs dfs -mv /user/hadoop/file1 /user/hadoop/file2
· hdfs dfs -mv hdfs://nn.example.com/file1 hdfs://nn.example.com/file2 hdfs://nn.example.com/file3 hdfs://nn.example.com/dir1
Exit Code:
Returns 0 on success and -1 on error.
put
Usage: hdfs dfs -put
Copy single src, or multiple srcs from local file system to the destination file system. Also reads input from stdin and writes to destination file system.
· hdfs dfs -put localfile /user/hadoop/hadoopfile
· hdfs dfs -put localfile1 localfile2 /user/hadoop/hadoopdir
· hdfs dfs -put localfile hdfs://nn.example.com/hadoop/hadoopfile
· hdfs dfs -put - hdfs://nn.example.com/hadoop/hadoopfile Reads the input from stdin.
Exit Code:
Returns 0 on success and -1 on error.
rm
Usage: hdfs dfs -rm [-f] [-r|-R] [-skipTrash] URI [URI ...]
Delete files specified as args.
Options:
· The -f option will not display a diagnostic message or modify the exit status to reflect an error if the file does not exist.
· The -R option deletes the directory and any content under it recursively.
· The -r option is equivalent to -R.
· The -skipTrash option will bypass trash, if enabled, and delete the specified file(s) immediately. This can be useful when it is necessary to delete files from an over-quota directory.
Example:
· hdfs dfs -rm hdfs://nn.example.com/file /user/hadoop/emptydir
Exit Code:
Returns 0 on success and -1 on error.
rmr
Usage: hdfs dfs -rmr [-skipTrash] URI [URI ...]
Recursive version of delete.
Note: This command is deprecated. Instead use hdfs dfs -rm -r
setfacl
Usage: hdfs dfs -setfacl [-R] [-b|-k -m|-x
Sets Access Control Lists (ACLs) of files and directories.
Options:
· -b: Remove all but the base ACL entries. The entries for user, group and others are retained for compatibility with permission bits.
· -k: Remove the default ACL.
· -R: Apply operations to all files and directories recursively.
· -m: Modify ACL. New entries are added to the ACL, and existing entries are retained.
· -x: Remove specified ACL entries. Other ACL entries are retained.
· --set: Fully replace the ACL, discarding all existing entries. The acl_spec must include entries for user, group, and others for compatibility with permission bits.
· acl_spec: Comma separated list of ACL entries.
· path: File or directory to modify.
Examples:
· hdfs dfs -setfacl -m user:hadoop:rw- /file
· hdfs dfs -setfacl -x user:hadoop /file
· hdfs dfs -setfacl -b /file
· hdfs dfs -setfacl -k /dir
· hdfs dfs -setfacl --set user::rw-,user:hadoop:rw-,group::r--,other::r-- /file
· hdfs dfs -setfacl -R -m user:hadoop:r-x /dir
· hdfs dfs -setfacl -m default:user:hadoop:r-x /dir
Exit Code:
Returns 0 on success and non-zero on error.
setfattr
Usage: hdfs dfs -setfattr -n name [-v value] | -x name
Sets an extended attribute name and value for a file or directory.
Options:
· -b: Remove all but the base ACL entries. The entries for user, group and others are retained for compatibility with permission bits.
· -n name: The extended attribute name.
· -v value: The extended attribute value. There are three different encoding methods for the value. If the argument is enclosed in double quotes, then the value is the string inside the quotes. If the argument is prefixed with 0x or 0X, then it is taken as a hexadecimal number. If the argument begins with 0s or 0S, then it is taken as a base64 encoding.
· -x name: Remove the extended attribute.
· path: The file or directory.
Examples:
· hdfs dfs -setfattr -n user.myAttr -v myValue /file
· hdfs dfs -setfattr -n user.noValue /file
· hdfs dfs -setfattr -x user.myAttr /file
Exit Code:
Returns 0 on success and non-zero on error.
setrep
Usage: hdfs dfs -setrep [-R] [-w]
Changes the replication factor 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.
Options:
· The -w flag requests that the command wait for the replication to complete. This can potentially take a very long time.
· The -R flag is accepted for backwards compatibility. It has no effect.
Example:
· hdfs dfs -setrep -w 3 /user/hadoop/dir1
Exit Code:
Returns 0 on success and -1 on error.
stat
Usage: hdfs dfs -stat URI [URI ...]
Returns the stat information on the path.
Example:
· hdfs dfs -stat path
Exit Code: Returns 0 on success and -1 on error.
tail
Usage: hdfs dfs -tail [-f] URI
Displays last kilobyte of the file to stdout.
Options:
· The -f option will output appended data as the file grows, as in Unix.
Example:
· hdfs dfs -tail pathname
Exit Code: Returns 0 on success and -1 on error.
test
Usage: hdfs dfs -test -[ezd] URI
Options:
· The -e option will check to see if the file exists, returning 0 if true.
· The -z option will check to see if the file is zero length, returning 0 if true.
· The -d option will check to see if the path is directory, returning 0 if true.
Example:
· hdfs dfs -test -e filename
text
Usage: hdfs dfs -text
Takes a source file and outputs the file in text format. The allowed formats are zip and TextRecordInputStream.
touchz
Usage: hdfs dfs -touchz URI [URI ...]
Create a file of zero length.
Example:
· hdfs dfs -touchz pathname
Exit Code: Returns 0 on success and -1 on error.