How can I do float comparison in Bash?

Question

lock_percent=$(echo "scale = 5; $value2*100/$value1" | bc)
value=`echo "$lock_percent" | bc`

    if [[ "$value" > "$8" ]]; then
       echo "Lock Percentage:$value percentage State Critical"
       exit $STATE_CRITICAL
    fi

I am not able to perform a float comparison with this. Where am I going wrong?

Answer 1

Bash itself can't use float. In this case maybe you can multiply by 10 or 100 (etc.) and get integer value which you can compare. Or, you can use bc comparison and return value:

echo "10.2>10.1" | bc

Answer 2

# float number comparison
fcomp() {
    awk -v n1="$1" -v n2="$2" 'BEGIN {if (n1+0<n2+0) exit 0; exit 1}'
}

# test and example
fcomp_test() {
    if fcomp "$1" "$2"; then
       echo "$1<$2"
    else
       echo "$1>=$2"
    fi
}

fcomp_test 0.0 0.1
fcomp_test 0.1 0.1
fcomp_test -0.1 0.1
fcomp_test 1e3 1e4
fcomp_test -1.34e3 1.03e4
fcomp_test ' 0 ' ' 1 '