Bash exit code 0 is truthy, but that's not how the if statement works: if ((0)); then echo 0=true; else echo 0=false; fi if ((1)); then echo 1=true; else echo

Bash exit code 0 is truthy, but that's not how the if statement works: if ((0)); then echo 0=true; else echo 0=false; fi if ((1)); then echo 1=true; else echo 1=false; fi # output 0=false 1=true To work as expected, the if statements should be rewritten as if ((i % 3 == 0 && i % 5 == 0)); then echo FizzBuzz and so on.