generate dynamic variable in unix
 

S1= 23450
J=1

I would like to get print value as below

echo $SJ
23450

s2= 23490

J=2

echo $S2
23490

but how can I achive in unix shell using echo statement, I am using such logic in loop and J is the counter.

What you are asking for can be done in bash but is messy and potentially dangerous. An array solution would be better:

I think you need the eval
try
eval echo \$S$J

(and be careful s2 and S2 are not the same)