Bash script: specify bc output number format

Question

Greetings!

I uses bс to make some calculations in my script. For example:

bc
scale=6
1/2
.500000

For further usage

Answer 1

Just do all your calculations and output in awk:

float_scale=6
result=$(awk -v scale=$floatscale 'BEGIN { printf "%.*f\n", scale, 1/2 }')

As an alternative, if you'd prefer to use bc and not use AWK alone or with 'bc', Bash's printf supports floating point numbers even though the rest of Bash doesn't.

result=$(echo "scale=$float_scale; $*" | bc -q 2>/dev/null)
result=$(printf '%*.*f' 0 "$float_scale" "$result")

The second line above could instead be:

printf -v $result '%*.*f' 0 "$float_scale" "$result"

Which works kind of like sprintf would and doesn't create a subshell.