How can I fetch a fsImage from a certain namenode/namespace?

[#1]

When there are multiple namespaces, <hdfs dfsadmin -fetchImage> command seems to fetch a fsImage from the default namespace.

What I need is to get fsImages from every namespaces.

How can I pass the target namespace when using dfsadmin command?

[#2]

@Si 

Try below command

hdfs dfsadmin -Dfs.defaultFS=hdfs://<name service> -fetchImage /tmp

Make sure the name service configs are already in place.

The general command line syntax is
bin/hadoop command [genericOptions] [commandOptions]

Generic options supported are
-conf <configuration file> specify an application configuration file
-D <property=value> use value for given property
-fs <local|namenode:port> specify a namenode