bash shell script two variables in for loop

Question

I am new to shell scripting. so kindly bear with me if my doubt is too silly.

I have png images in 2 different directories and an executable which takes an images f

Answer 1

If you don't mind going off the beaten path (bash), the Tool Command Language (TCL) has such a loop construct:

#!/usr/bin/env tclsh

set list1 [glob dir1/*]
set list2 [glob dir2/*]

foreach item1 $list1 item2 $list2 {
    exec command_name $item1 $item2
}

Basically, the loop reads: for each item1 taken from list1, and item2 taken from list2. You can then replace command_name with your own command.