Hi all
HDFS commands examples
View the usage of hadoop fs
# hadoop fs
Enter the following -ls command to view the contents of the user’s root directory in HDFS, which is /user/root:
# hadoop fs -ls
View the contents of the /user directory in HDFS:
# hadoop fs -ls /user
-ls command again, but this time specify the root HDFS folder:
# hadoop fs -ls /
The output should look like:
Found 6 items
drwxrwxrwt – yarn hdfs 0 2013-08-20 13:59 /app-logs
drwxr-xr-x – hdfs hdfs 0 2013-08-20 13:53 /apps
Switch to user:
# su – hdfs
Make a new directory in HDFS named /user/root:
$ hadoop fs -mkdir /user/root
Change the permissions to make root the owner of the directory:
$ hadoop fs -chown root /user/root
Switch back to the root user:
$ exit
Create a directory named sample in HDFS:
hadoop fs -mkdir sample
Verify the folder was created successfully:
# hadoop fs -ls Found 1 items
Create a couple of subdirectories of sample:
# hadoop fs -mkdir sample/sample1
Delete the sample2 folder (and recursively its subcontents)
# hadoop fs -rm -R sample/sample2
run the –ls -R command:
# hadoop fs -ls -R
The directory structure of the output
.Trash
.Trash/Current
.Trash/Current/user
.Trash/Current/user/root
Put a file into the sample folder. Change directories to
/var/log/hadoop/hdfs:
# cd /var/log/hadoop/hdfs
Notice this folder contains a file named hdfs-audit.log:
# tail hdfs-audit.log
Run the following -put command to copy hdfs-audit.log into the sample folder in HDFS:
# hadoop fs -put hdfs-audit.log sample/
Verify the file is in HDFS by listing the contents of sample:
# hadoop fs -ls sample
Copy the hdfs-audit.log file in sample to another folder in HDFS:
# hadoop fs -cp sample/hdfs-audit.log sample/sample1/copy.log
# hadoop fs -getmerge sample /tmp/merged.txt
