Bash script: specify bc output number format

Question

Hello!

I use bc to do some calculations in my script. For instance:

bc
scale=6
1/2
.500000

For further use in my script, I need "0.500000" set to ".500000".

Could you help me customize the bc output format for my case?

Answer 1

In one line:

printf "%0.6f\n" $(bc -q <<< scale=6\;1/2)

Answer 2

Quick and dirty, since it scaleapplies only to decimal digits, and bcdoes not have a sprintf-like function :

$ bc
scale = 6
result = 1 / 2
if (0 <= result && result < 1) {
    print "0"
}
print result;

Answer 3

awk:

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

, bc, AWK "bc", Bash printf , Bash .

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

:

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

sprintf .

Answer 4

, :

float_scale=6

function float_eval()
{
    local stat=0
    local result=0.0
    if [[ $# -gt 0 ]]; then
        result=$(echo "scale=$float_scale; $*" | bc -q | awk '{printf "%f\n", $0}' 2>/dev/null)
        stat=$?
        if [[ $stat -eq 0  &&  -z "$result" ]]; then stat=1; fi
    fi
    echo $result
    return $stat
}

Answer 5

echo "scale=3;12/7" | bc -q | sed 's/^\\./0./;s/0*$//;s/\\.$//'

Answer 6

bc ? bc ?

some_math.bc

scale=6
output=1/2
print output

, :

$ bc -q some_math.bc | awk '{printf "%08f\n", $0}'
0.500000

If I only need an output string for a null value for formatting, I would use awk.