In Shell script how can i loop through a variable containing other variables

Using bash

With bash, we can use arrays and indirection:

parentClients=(name1 name2)
effectedClients=(value1 value2)
otherClients=(something1 something2 something3)
client_types=(parentClients effectedClients otherClients)
for client in "${client_types[@]}"
do
   echo "client=$client"
   c=$client[@]
   for ct in "${!c}"
   do
      echo "  ct=$ct"
   done
   echo "done with one set"
done

This produces the output:

client=parentClients
  ct=name1
  ct=name2
done with one set
client=effectedClients
  ct=value1
  ct=value2
done with one set
client=otherClients
  ct=something1
  ct=something2
  ct=something3
done with one set

The statement parentClients=(name1 name2) creates an array named parentClients with values name1 and name2. The expression ${!c} uses indirection to access the array whose name is given by c.

Using POSIX shell

With a POSIX shell, we must use variables instead of arrays and, in place of indirection, we use eval:

parentClients="name1 name2"
effectedClients="value1 value2"
otherClients="something1 something2 something3"
client_types="parentClients effectedClients otherClients"
for client in $client_types
do
   echo "client=$client"
   eval "client_list=\$$client" # Potentially dangerous step
   for ct in $client_list
   do
      echo "  ct=$ct"
   done
   echo "done with one set"
done

Because eval requires some trust in the source of the data, it should be used with caution.

This produces the output:

client=parentClients
  ct=name1
  ct=name2
done with one set
client=effectedClients
  ct=value1
  ct=value2
done with one set
client=otherClients
  ct=something1
  ct=something2
  ct=something3
done with one set