Chỉnh sửa tệp /etc/hosts bằng bash script như thế nào?

#!/bin/bash
# A script to add, remove, and list entries in the hosts file


# Function to add an entry to the hosts file
add_entry() {
    # Get user input for IP address and server name
    read -p "Enter IP address: " ip_address
    read -p "Enter server name: " server_name

    # Check if the input is not empty
    if [ -z "$ip_address" ] || [ -z "$server_name" ]; then
        echo "IP address and server name cannot be empty."
        exit 1
    fi

    # Append the entry to the hosts file
    echo "$ip_address $server_name" >> /etc/hosts

    echo "Entry added to /etc/hosts: $ip_address $server_name"
}

# Function to remove an entry from the hosts file
remove_entry() {
    # Get user input for IP address or server name to remove
    read -p "Enter IP address or server name to remove: " entry_to_remove

    # Check if the input is not empty
    if [ -z "$entry_to_remove" ]; then
        echo "Entry cannot be empty."
        exit 1
    fi

    # Check if the entry exists in the hosts file
    if grep -q "$entry_to_remove" /etc/hosts; then
        # Remove the entry from the hosts file using sed
        sed -i.bak -e "/$entry_to_remove/d" /etc/hosts

        echo "Entry removed from /etc/hosts: $entry_to_remove"
    else
        echo "Entry does not exist in /etc/hosts: $entry_to_remove"
    fi
}


# Function to list all active entries in the hosts file
list_entries() {
    echo "Non-commented entries in /etc/hosts:"
    grep -E -v '^\s*#' /etc/hosts
}


# Check if the script is executed with root privileges
if [[ $EUID -ne 0 ]]; then
   echo "This script must be run as root."
   exit 1
fi

# Display menu for user choice
echo "1. Add entry"
echo "2. Remove entry"
echo "3. List entries"
read -p "Enter your choice (1, 2, or 3): " choice

case $choice in
    1)
        add_entry
        ;;
    2)
        remove_entry
        ;;
    3)
        list_entries
        ;;
    *)
        echo "Invalid choice. Exiting."
        exit 1
        ;;
esac