Data Validation

Number Validation

Check Digits

Scripts often receive numbers as strings. A validation step should confirm the shape before arithmetic uses the value.

Program

Play the script to choose an input value and see whether the digit check passes.

number_validation.sh 
#!/usr/bin/env bash

input=
if [[ "$input" =~ ^[0-9]+$ ]]; then
    status="number"
else
    status="invalid"
fi
echo "$input:$status"

#!/usr/bin/env bash

input=
if [[ "$input" =~ ^[0-9]+$ ]]; then
    status="number"
else
    status="invalid"
fi
echo "$input:$status"
validation Validation checks input before later logic trusts it.
regex `^[0-9]+$` accepts only one or more digits.
status word A compact status makes validation failures easy to test.