subtraction in linux shell if

Question

In linux bash shell, how to subtract a variable from another in if? I've tried the following:

#!/bin/bash
start=0
end=1
if [ end - start -eq 1 ]; then
    echo "right"
fi

It doesn't work.

Answer 1

Since you specifically mentioned bash, use its arithmetic support:

#!/bin/bash
start=0
end=1
if ((end - start == 1)); then
    echo "right"
fi

Answer 2

Do something something like as shown below:

#!/bin/bash
start=0
end=1
if [ `expr $end - $start` -eq 1 ]; then
    echo "right"
fi