I need a way to build variable in this manner:

variable_$i
Inside a for loop i need to create it.
where i goes from 1 to 30..
and then i need to print them on screen with echo $variable_$i
which is the best way to do this?

echo ${variable}_${i}

curly braces are used to emphesize the actual name of the variable, usually it's not necessary but sometimes a bit confusing constructions are used,

An example:

#!/bin/sh

variable=AA
i=1

while [ i -le 30 ]; do
  echo ${variable}_${i}
  let i=i+1
done

Thanks for your reply.
How can i assign a value to this variable
${variable}_${i}="somestring" is it work?

thread moved to "Shell Programming and Scripting". please watch out to post in the right sub forum!

The way to learn scripting/programming or whatever is to do it yourself, just try it out......

Regards

this is not a one single variables. these are two distinct variables.