Compare floating point numbers using regex in Bash-CodePudding

I need to check if current NTP offset is biger than 2.xxxxx , where xxx is any number for example 2.005596757,2.006086349

offset=$(ntpdate -q 1.2.3.4 | head -1 | cut -d " " -f 6 | sed "s/.$//")
echo $offset

current offset variable is: 0.841816 so need to compare if X.XXXXXX is bigger or equal to 2.XXXXXXXXX , where X is any number in range [0-9]

offset=$(ntpdate -q 10.160.82.10 | head -1 | cut -d " " -f 6 | sed "s/.$//")

        
     if [ $offset -ge ([2] \.?[0-9]*) ]
      then
       echo "offset too high"
     fi

But getting error

./1.sh: line 9: syntax error near unexpected token `('
./1.sh: line 9: `if [ $offset -ge ([2] \.?[0-9]*)|([0-9]*\.[0-9] ) ]'

CodePudding user response：

Why don't you compare only the integer part? Like:

if [ ${offset%.*} -ge 2 ]; then
  echo offset too high
fi

CodePudding user response：

For comparing a floating point number it is better to use awk or perl as bash can only handle integer numbers.

You may consider this awk solution that eliminates head, cut and sed as a bonus:

if ntpdate -q 1.2.3.4 | awk 'NR == 1 && $6 < 2 {exit 1} {exit 0}'; then
   echo 'offset too high'
fi