How to unzip file in hadoop? - hadoop

I was trying to unzip a zip file, stored in Hadoop file system, & store it back in hadoop file system. I tried following commands, but none of them worked.
hadoop fs -cat /tmp/test.zip|gzip -d|hadoop fs -put - /tmp/
hadoop fs -cat /tmp/test.zip|gzip -d|hadoop fs -put - /tmp
hadoop fs -cat /tmp/test.zip|gzip -d|hadoop put - /tmp/
hadoop fs -cat /tmp/test.zip|gzip -d|hadoop put - /tmp
I get errors like gzip: stdin has more than one entry--rest ignored, cat: Unable to write to output stream., Error: Could not find or load main class put on terminal, when I run those commands. Any help?
Edit 1: I don't have access to UI. So, only command lines are allowed. Unzip/gzip utils are installed on my hadoop machine. I'm using Hadoop 2.4.0 version.

To unzip a gzipped (or bzipped) file, I use the following
hdfs dfs -cat /data/<data.gz> | gzip -d | hdfs dfs -put - /data/
If the file sits on your local drive, then
zcat <infile> | hdfs dfs -put - /data/

I use most of the times hdfs fuse mounts for this
So you could just do
$ cd /hdfs_mount/somewhere/
$ unzip file_in_hdfs.zip
http://www.cloudera.com/content/www/en-us/documentation/archive/cdh/4-x/4-7-1/CDH4-Installation-Guide/cdh4ig_topic_28.html
Edit 1/30/16: In case if you use hdfs ACLs: In some cases fuse mounts don't adhere to hdfs ACLs, so you'll be able to do file operations that are permitted by basic unix access privileges. See https://issues.apache.org/jira/browse/HDFS-6255, comments at the bottom that I recently asked to reopen.

To stream the data through a pipe to hadoop, you need to use the hdfs command.
cat mydatafile | hdfs dfs -put - /MY/HADOOP/FILE/PATH/FILENAME.EXTENSION

gzip use -c to read data from stdin
hadoop fs -put doesnt support read the data from stdin
I tried a lots of things and would help.I cant find the zip input support of hadoop.So it left me no choice but download the hadoop file to local fs ,unzip it and upload to hdfs again.

Related

Hadoop: dfs is deprecated but hdfs class not found

I'm new to Hadoop, and am trying to check what data is available in HDFS. However, the dfs command returns a response that indicates the class is deprecated, and that hdfs should be used:
-bash-4.2$ hadoop dfs -ls
DEPRECATED: Use of this script to execute hdfs command is deprecated.
Instead use the hdfs command for it.
ls: `.': No such file or directory
When I try the hdfs command, though, I get what appears to be a Java class lookup error:
-bash-4.2$ hadoop hdfs -ls
Error: Could not find or load main class hdfs
Is there something wrong with my Hadoop setup, or have others encountered this catch-22?
It is hadoop fs or hdfs dfs, then -ls
You can run hdfs dfs -ls / to check the root of HDFS, but you will get .: No such file or directory because the output of echo "hdfs:///user/$(whoami)" does not exist yet, and you need to make it using hadoop fs -mkdir -p hdfs:///user/$(whoami).
That command must be repeated for every user account that attempts to access their HDFS user directory

Store file on hadoop

I want to store some .tbl files in hadoop.
I am using this command: hadoop fs -put customer.tbl
But Im getting:
Usage: java FsShell [- put <localsrc> .. <dst>]
If I do hadoop fs -cat cusomer.tbl
It appears that file does note exist.
It seems like you need to provide local-src and HDFS-dst.
Can you try to add destination?
e.g. hadoop fs -put customer.tbl .
please also try execute "ls" on the HDFS:
hadoop fs -ls
please also try execute "ls" on the HDFS using hdfs command, 'hdfs' should be found under hadoop-version-number/bin/:
hdfs dfs -ls

I am getting errors while copying files from local to hdfs

I am getting error while copying files from local file system to hdfs,
will you please help me regarding this,
I am using this command :
hadoopd fs -put text.txt file
put and copyFromLocal command helps you to copy data from your local system to HDFS,provided you have the permission to do so.
hadoop fs -put /path/to/textfile /path/to/hdfs
OR
hadoop dfs -put /path/to/textfile /path/to/hdfs
Comming to your error:
You typed the above command as
hadoopd fs
use
hadoop dfs -put /text.txt /file
hadoop dfs -put /path/to/local/file /path/to/hdfs/file
You can use following command
hadoop fs -copyFromLocal text.txt <path_to_hdfs_directory_where_you_want_to_keep_text.txt>
Without knowing the specific error you are getting, it's difficult to answer. The other responders posted the proper syntax. However, it is not uncommon to see permission issues when attempting to copy files to HDFS.
By default the user and group are typically "hdfs" and "supergroup". Your user account likely doesn't belong to "supergroup" and will get permission denied errors. Try running the command as:
sudo -u hdfs hadoop fs -put /path/to/local/file /path/to/hdfs/file
or
sudo -u hdfs hadoop dfs -put /path/to/local/file /path/to/hdfs/file
You can get around having to do this by changing the ownership and permission of the destination directory on HDFS to be more permissive.
"DataStreamer Exception: org.apache.hadoop.ipc.RemoteException: java.io.IOException: File /user/hduser/myfile could only be replicated to 0 nodes, instead of 1 at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.getAdditionalBlock". From this I thinrk your data node is not running/properly. Check that in cluster UI.Then try
hadoop dfs -put /path/file /hdfs/file (hadoop YARN)
hadoop fs -copyFromLocal /path/file /hdfs/file (hadoop1.x)

hadoop fs -put command

I have constructed a single-node Hadoop environment on CentOS using the Cloudera CDH repository. When I want to copy a local file to HDFS, I used the command:
sudo -u hdfs hadoop fs -put /root/MyHadoop/file1.txt /
But,the result depressed me:
put: '/root/MyHadoop/file1.txt': No such file or directory
I'm sure this file does exist.
Please help me,Thanks!
As user hdfs, do you have access rights to /root/ (in your local hdd)?. Usually you don't.
You must copy file1.txt to a place where local hdfs user has read rights before trying to copy it to HDFS.
Try:
cp /root/MyHadoop/file1.txt /tmp
chown hdfs:hdfs /tmp/file1.txt
# older versions of Hadoop
sudo -u hdfs hadoop fs -put /tmp/file1.txt /
# newer versions of Hadoop
sudo -u hdfs hdfs dfs -put /tmp/file1.txt /
--- edit:
Take a look at the cleaner roman-nikitchenko's answer bellow.
I had the same situation and here is my solution:
HADOOP_USER_NAME=hdfs hdfs fs -put /root/MyHadoop/file1.txt /
Advantages:
You don't need sudo.
You don't need actually appropriate local user 'hdfs' at all.
You don't need to copy anything or change permissions because of previous points.
try to create a dir in the HDFS by usig: $ hadoop fs -mkdir your_dir
and then put it into it $ hadoop fs -put /root/MyHadoop/file1.txt your_dir
Here is a command for writing df directly to hdfs file system in python script:
df.write.save('path', format='parquet', mode='append')
mode can be append | overwrite
If you want to put in in hdfs using shell use this command:
hdfs dfs -put /local_file_path_location /hadoop_file_path_location
You can then check on localhost:50070 UI for verification

Hadoop -copyFromLocal cannot find input file

sudo -u hdfs hadoop fs -copyFromLocal input.csv input.csv
copyFromLocal: `input.csv': No such file or directory
Can anyone tell me the exact reason why I am getting this kind of error? I gave all permissions to the input.csv file and I even changed the owner to hdfs. I am new to Hadoop and Hbase.
In this case you are trying to read the file as the hdfs user, which may not have permission to view this file. To test, do this:
sudo -u hdfs cat input.csv
If you get permission denied, you either need to change the permissions of this file so the hdfs user can read it (or if it already has read permissions, move the file to a directory that the hdfs user can read), or use a different user that has permission to access the local and the remote directories/files.
You need to make sure that user hdfs has read permission to all the parent directories of input.csv along the path.
syntax: hadoop dfs -copyFromLocal completelocalfilesystempath hdfspath
Example: Let input.csv be in localpath /usr/examples and my hdfs path where it needs to be copied is /usr/input so the command will be
hadoop dfs -copyFromLocal /usr/examples/input.csv /usr/input/
To copy files you can run it like this:
cat input.csv | sudo -u hdfs hadoop fs -put - input.csv

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