bash - How to check if a number is within a range in shell

Question

I want to just insert number between two values, and otherwise the script repeated until correct number.

This is my script and it does not work correctly:

validation(){
read number
if [ $number -ge 2 && $number -ls 5 ]; then
    echo "valid number"
    break
else
    echo "not valid number, try again"
fi

}

echo "insert number"
validation
echo "your number is" $number

Answer 1

If you are using Bash, you are better off using the arithmetic expression, ((...)) for readability and flexibility:

if ((number >= 2 && number <= 5)); then
  # your code
fi

To read in a loop until a valid number is entered:

#!/bin/bash

while :; do
  read -p "Enter a number between 2 and 5: " number
  [[ $number =~ ^[0-9]+$ ]] || { echo "Enter a valid number"; continue; }
  if ((number >= 2 && number <= 5)); then
    echo "valid number"
    break
  else
    echo "number out of range, try again"
  fi
done

((number >= 2 && number <= 5)) can also be written as ((2 <= number <= 5)).

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See also:

• Test whether string is a valid integer
• How to use double or single brackets, parentheses, curly braces