You should play around testing your with your shell and the test command, if you better use 1 or 2 brackets on each side, which kind of arithmetic operators you can use (-eq, -gt, <=, ==, =, <>, ...) and if you can use something similar to typeset to declare variable values as integer for example, which your shell doesn't seem to know.

I tried sh/bash, ksh and each of them knows "typeset" for example. What OS are you on and what kind of shell are you using (I saw the shebang, but check the package's/binary's version maybe)?