Reconnect Raspberry Pi to headless Wi-Fi network using flags, useful if the device does not automatically connect on boot.

reconnect-pi.sh

#!/bin/bash

echo "[-] Running reconnect-pi.sh@faisaln..."

while getopts ":n:u:p:c" opt; do
  case $opt in
    n)
      network_name="$OPTARG"
      ;;
    u)
      network_username="$OPTARG"
      ;;
    p)
      network_password="$OPTARG"
      ;;
    c)
      ca_cert_path="$OPTARG"
      ;;
    \?)
      echo "Invalid option: -$OPTARG" >&2
      exit 1
      ;;
    :)
      echo "Option -$OPTARG requires an argument." >&2
      exit 1
      ;;
  esac
done

echo "[1] Validating current network..."
if ping -c 1 0 &> /dev/null; then
    echo "[1] Connected to $(iwgetid -r || echo 'ethernet')."
    if tailscale status &> /dev/null; then
        echo "[2] Tailscale is already running. Skipping Tailscale setup..."
        if ! iwgetid -r || iwgetid -r | grep -q "Faisal N"; then
            echo "[3] Setting up headless network..."
            if [[ -z "$network_name" ]]; then
                while true; do
                    read -p "[3] Network name: " network_name
                    if [[ -n "$network_name" ]]; then
                        break
                    else
                        echo "[3] Network name required."
                    fi
                done
            fi
            found=false
            if command -v nmcli &> /dev/null; then
                nmcli device wifi rescan >/dev/null 2>&1 || true
                if nmcli -t -f SSID device wifi list | grep -xFq "$network_name"; then
                    found=true
                fi
            fi
            if [ "$found" = false ]; then
                if sudo iwlist wlan0 scan | grep -qw "$network_name"; then
                    found=true
                fi
            fi
            if $found; then
                echo "[3] $network_name network found. Creating..."
                existing_connections=$(nmcli -t -f NAME connection show | grep -w "$network_name")
                if [ -n "$existing_connections" ]; then
                    echo "[3] Existing connection for $network_name found. Attempting to connect..."
                    sudo nmcli connection up "$network_name" ifname wlan0
                    sleep 10
                    if nmcli -t -f NAME connection show --active | grep -qw "$network_name"; then
                        echo "[3] Connected to network $network_name."
                        exit 0
                    else
                        echo "[3] Removing existing connections for $network_name..."
                        echo "$existing_connections" | while IFS= read -r conn; do
                            sudo nmcli connection delete "$conn"
                            echo "[3] Deleted connection: $conn"
                        done
                    fi
                fi
                if [[ -z "$network_password" ]]; then
                    while true; do
                        read -sp "[3] Enter password for $network_name: " network_password
                        if [[ -n "$network_password" ]]; then
                            break
                        else
                            echo "[3] Network password required."
                        fi
                    done
                fi
                if [[ "$network_name" == *"wpa"* ]]; then
                    echo "[3] WPA network found."
                    if [[ -z "$network_username" ]]; then
                        while true; do
                            read -p "[3] Enter username for $network_name: " network_username
                            if [[ -n "$network_username" ]]; then
                                break
                            else
                                echo "[3] Network username required."
                            fi
                        done
                    fi
                    if [[ -n "$ca_cert_path" ]]; then
                        if [[ ! -f "$ca_cert_path" ]]; then
                            echo "[3] CA certificate file not found at $ca_cert_path. Exiting."
                            exit 1
                        fi
                        sudo bash -c 'cat <<EOF > /etc/wpa_supplicant/wpa_supplicant.conf
network={
ssid="'"$network_name"'"
key_mgmt=WPA-EAP
eap=PEAP
identity="'"$network_username"'"
password="'"$network_password"'"
phase1="peaplabel=1"
phase2="auth=MSCHAPV2"
ca_cert="/etc/wpa_supplicant/ca-cert.pem"
}
EOF'
                    else
                        sudo bash -c 'cat <<EOF > /etc/wpa_supplicant/wpa_supplicant.conf
network={
ssid="'"$network_name"'"
key_mgmt=WPA-EAP
eap=PEAP
identity="'"$network_username"'"
password="'"$network_password"'"
phase1="peaplabel=1"
phase2="auth=MSCHAPV2"
ca_cert="/etc/wpa_supplicant/empty-ca.pem"
}
EOF'
                        sudo touch /etc/wpa_supplicant/empty-ca.pem
                    fi
                else
                    sudo bash -c 'cat <<EOF > /etc/wpa_supplicant/wpa_supplicant.conf
network={
ssid="'"$network_name"'"
psk="'"$network_password"'"
}x  
EOF'
                fi
                if [[ "$network_name" == *"wpa"* ]]; then
                    sudo nmcli connection add type wifi ifname wlan0 \
                        con-name "$network_name" ssid "$network_name" \
                        802-11-wireless.mode infrastructure \
                        802-11-wireless-security.key-mgmt WPA-EAP \
                        802-1x.eap peap \
                        802-1x.identity "$network_username" \
                        802-1x.password "$network_password" \
                        802-1x.phase2-auth mschapv2 \
                        $ca_opt \
                        connection.autoconnect yes
                else
                    sudo nmcli connection add type wifi ifname wlan0 con-name $network_name ssid "$network_name" 802-11-wireless.mode infrastructure
                    sudo nmcli connection modify $network_name \
                        802-1x.identity "$network_username" \
                        802-1x.password "$network_password" \
                        802-11-wireless-security.psk "$network_password"
                fi
                sudo nmcli connection modify $network_name connection.autoconnect yes
                echo "[3] Connecting to $network_name..."
                sudo nmcli connection up $network_name ifname wlan0
                sleep 10
                if nmcli -t -f NAME connection show --active | grep -qw "$network_name"; then
                    echo "[3] Connected to network $network_name."
                else
                    echo "[3] Failed to connect to network $network_name. Please check your credentials and try again."
                    exit 1
                fi
            else
                echo "[3] $network_name network not found. Please ensure the network is available."
                exit 1
            fi
        else
            echo "[3] Already connected to headless network, skipping network setup..."
        fi
    fi
    echo "[+] reconnect-pi.sh completed."
    exit 0
else
    echo "[1] No internet connection found. Connect to the internet and try again."
    exit 1
fi

echo "[-] reconnect-pi.sh aborted."