Bash Quick Start Guide

Fixed or floating-point arithmetic

If you try out a few of the preceding mathematical expressions, you might notice that some of the expanded values seem wrong:

$ printf '%.2f\n' "$((3/2))"
1.00

You may have expected a value such as 1.50 to be returned here, but Bash does not support floating-point or fixed-point arithmetic, only integer arithmetic. Fractional parts for these operations are lost.

If you need to perform arithmetic with non-integers using tools that are highly likely to be available on a POSIX system, your best bets are the bc calculator for fixed-point, or an AWK program for floating-point:

$ bc <<'EOF'
scale=2
3/2
EOF
1.50
$ awk 'BEGIN { printf "%.2f\n", 3/2 }'
1.50

If you have to do a lot of these sorts of operations, you ...