Shell Programming and Scripting

I am having trouble running a .sh file. The code 'x=${file_name:0:$z-11}' is giving me a bad substitution error. However when I run in BASH it works. Thing is when this goes to production the .sh will not be running in BASH. Is there a way to substring a string not in BASH or a way to invoke BASH and still run the .sh without any pauses. Thanks!

file_name="12366293address.txt"

#Grabs length of file_name string
z=${#file_name}

#Substrings file_name
x=${file_name:0:$z-11}

Edward,
A quick solution is to place the first line in the shell:

Code:

#!/bin/bash

Try first:

Code:

which bash

works great!! Thanks!!!!