bash integer number only

Question

I can't seem to allow single integer input only. If someone puts abc, it will work.

But if someone puts in abc123 or 123abc it will still treat it as a valid integer

# input to be an integer.
validate_integer(){

    if [ !  "$#" -eq "1" ]; then
            error "Please enter one numberic value only"
            return 1
    elif [[ "$1" =~ ^[[:alpha:]]+$ ]]; then
            error "Input must be a NUMBER"
            return 1
    else
            return 0
    fi
}

Refer this. http://stackoverflow.com/questions/2210349/bash-test-whether-string-is-valid-as-an-integer — KeithSmith, Nov 23 '13 at 22:38

score 2 · Answer 1 · answered Nov 23 '13 at 23:44

Change this line:

elif [[ "$1" =~ ^[[:alpha:]]+$ ]]; then

to this:

elif ! [[ "$1" =~ ^[[:digit:]]+$ ]]; then

There, ^[[:digit:]]+$ means the string must be composed of digits from beginning to end, and it must be 1 or more characters long. We negate this with !, to handle the case when the string does not satisfy this condition (not fully numeric).

bash integer number only

1 Answers1