Compare negative numbers in bash [duplicate]

问题

This question already has answers here:

Comparing numbers in Bash (8 answers)

Closed last year.

How can i accomplish number comparison involving negative numbers?

if [[ "-2" > "-1" ]]; then
    echo "-2 >-1"
else
    echo "-2 <=-1"
fi

I also tried

if [ '-2' -lt '-1' ]; then

but the condition always behaves as if -2 would be greater than -1.

The comparisons work when i do not use negative numbers.

I would like a solution in pure bash if possible.

回答1:

Seems to work correctly:

if [[ "-2" -gt "-1" ]]; then
    echo "-2 >-1"
else
    echo "-2 <=-1"
fi

Output:

-2 <=-1

You might want to use ((...)) which enables the expression to be evaluated according to rules of Shell Arithmetic.

$ ((-2 <= -1)) && echo Smaller or equal || echo Larger
Smaller or equal
$ ((-2 <= -3)) && echo Smaller or equal || echo Larger
Larger

回答2:

-lt means less than. And indeed, -2 is less than -1.

Your want to use -gt, greater than.

回答3:

$ a=-2
$ [ $a -le -1 ] && echo "i am lower or equal than -1"
i am lower or equal than -1

or

if [ $a -le -1 ]; then
  echo "i am lower or equal than -1"
fi

To make it "greater than", you need ge (greater or equal) or gt (strictly greater than).

来源：https://stackoverflow.com/questions/17945187/compare-negative-numbers-in-bash