How to find the name of supergroup in hadoop and list all the members of the group?

[#1]

Hi there,

How to find the name of supergroup in hadoop and list all the members of the group?

I know hdfs is the super user in hadoop, but SuperGroup name

[#2]

Is dfs.permissions.superusergroup in hdfs-site.xml what you are looking for?

[#3]

yes. But, how to list all the users in the superusergroup?

I found superusergroup : hdfs in hdfs-site.xml. But, how to find the users in the group hdfs.

[#4 · Accepted solution]

@Jeeva Jeeva - There is a property "dfs.permissions.superusergroup" in hdfs-site.xml which specifies the superusergroup.

Please see below apache guide for HDFS Permissions:

https://hadoop.apache.org/docs/r2.4.1/hadoop-project-dist/hadoop-hdfs/HdfsPermissionsGuide.html

To list all the users belonging to the supergroup, its just like getting users belonging to a group in linux. Below is good article on that:

https://www.cyberciti.biz/faq/linux-list-all-members-of-a-group/

[#5]

Hi Namit Maheshwari,

Thanks for your time to reply. Your answer saved my life and one more question

How to see the members of the superusergroup for a namenode?

In my case, the super user is "hdfs".

I have been asked to find all the members of the superuser group.

/etc/group file is not for the namenode. So, there should be some other way.

[#6]

Hi Jeeva,

Find the superusergroup value in hdfs-site.xml. Lets say for instance this value is 'hadoop'

Once you find that value, you need to do is "grep 'superusergroup:' /etc/group"

i.e if that value is hadoop, it will be:

grep 'hadoop:' /etc/group

This should return you the list of all users belonging to the supergroup.

[#7]

Hi Maheshwari,

Our superusergroup is hdfs

That's what i did. He asked me where i got these members from and i told from /etc/group file. But, Technical Lead said something different. Here is the conversation we had below.

Jeeva:I got it from /etc/group file

Fred: that is correct for this particular server

how about what namenode?

that's where 'hdfs groups' tell you

[#8]

I think what he means is to check the same on the namenode hosts.

[#9]

Could you suggest me how to check on the namenode?

[#10]

You just need to logon to the namenode hosts and run the same grep command on the /etc/group file