Logical_OR_operator.sh

#! /bin/bash
age=60

# if [ "$age" -gt 18 -o "$age" -lt 30 ]  alternate choise of and opr. 
# if [[ "$age" -gt 18 || "$age" -lt 30 ]]  alternate choise of and opr. 
# if important

if [ "$age" -gt 18 ] || [ "$age" -lt 30 ]
then
    echo "valid age"
    else
    echo "age not valid"
fi