Busybox ash (Almquist shell) shell and Debian dash (Debian Almquist shell) are lightweight Unix shell and they are a variant of System V.4 variant of the Bourne shell. Ash/dash shell is known to be very small and is used mainly in embedded (ash) devices and installation scripts (Debian/Ubuntu setup).
Unfortunately they do not support arrays, which could be really a problem in many cases. But we can simulate the arrays with eval function.
So if you need to write a ash/dash script let’s say for an installation script of Ubuntu or Debian or a script for an embedded device, which uses busybox or even you do not want to use arrays in bash, you can follow the consepts below – create variable with a “name” concatenated with a number.

• 1) Set a variable

  It can be done with two ways:

  1. for myi in 0 1 2 ; do
         setvar mvar$myi "Payload: $myi"
     done
     

  2. for myi in 0 1 2 ; do
         eval mvar$myi=\"Payload: $myi\"
     done
     

  This will create variables with names:

  mvar1, mvar2, mvar3

  and they can be used in any place of your script after the creation of the variables using “eval” or accessing them with the names.

  * bash shell do not support the command “setvar”, so for bash scripts use only eval version.

• 2) Use a variable

1. using “eval”

   for myi in 0 1 2 ; do
       eval echo \$mvar$myi
   done
   
   myi=1
   eval newvar="\$mvar$myi"
   echo $newvar
   

2. direct access

   echo $mvar2
   $mvar2="Payload 20"
   echo $mvar2