How to check if running as root in a bash script

Question

I\'m writing a script that requires root level permissions, and I want to make it so that if the script is not run as root, it simply echoes \"Please run as root.\" and exit

Answer 1

#!/bin/bash

# GNU bash, version 4.3.46
# Determine if the user executing this script is the root user or not

# Display the UID
echo "Your UID is ${UID}"

if [ "${UID}" -eq 0 ]
then
    echo "You are root"
else
    echo "You are not root user"
fi

Editor's note: If you don't need double brackets, use single ones for code portability.