accessing variable name's variable value

[sathiya]

i want to access the variable name's variable value as

a=testing
b=a

how to print by only using variable b.
echo ${$b} --> it should print testing, how to do that..
( i know this echo will say error )

by the above example, if you are not able to understand.
I have the b variable has value "a", which is the variable name "a",
i need to access that variable, by knowing only the second variable name ????

[radoulov]

% a=testing
% b=a
% eval print \$$b
testing

Use printf if your shell does not have the print builtin.

[fox000002]

if using BASH, it can be

a=testing 
b=a
eval echo $$b

[radoulov]

if using BASH, it can be

a=testing 
b=a
eval echo $$b

I believe you meant:

eval echo \$$b

With recent bash versions it could be even:

$ a=testing 
$ b=a
$ printf "%s\n" "${!b}"
testing