Question

I have the following script:

  #!/bin/sh
  r=3
  r=$((r+5))
  echo r

However, I get this error:

Syntax error at line 3: $ unexpected.

I don’t understand what I’m doing wrong. I’m following this online guide to the letter http://www.unixtutorial.org/2008/06/arithmetic-operations-in-unix-scripts/

Answer 1

This sounds fine if you’re using bash, but $((r+5)) might not be supported if you’re using another shell. What does /bin/sh point to? Have you considered replacing it with /bin/bash if it’s available?