Bash script that allows you to access an VM remotely via VNC. With the script, you can easily add / change a VNC port in a VM conf file without needing to install VNC server directly on each VM. This has only been tested for Linux guests on a vanilla Proxmox installation.

proxmoxvnc.sh

#!/bin/bash

# ProxmoxVNC
# Use this script to add a VNC port to a Proxmox virtual machine for remote access.
# To access the VM remotely, enter the VM IP address and the port # shown in the
# output of the script. The port # will always start with 59.
#
# You can save and run this script from anywhere on your system.
# This script has only been tested on Linux guest on a vanilla Proxmox installation.
# https://gist.github.com/smithj33

echo
echo Enter VM#:
read vm
echo
echo "======================================================="
echo
echo Checking if VNC port exists...
echo
if grep vnc /etc/pve/local/qemu-server/$vm.conf
then
    port=$(grep vnc /etc/pve/local/qemu-server/$vm.conf | cut -b 20-)
    echo "*****************************"
    echo "VNC Port $port already exists!"
    echo "*****************************"
    echo
    echo "You can access your VM remotely at <Proxmox IP>:59$port"
    echo
    echo "======================================================="
    echo
    echo Would you like to change the port?\(\y/n\)\:
    read response
    echo

    if [[ "$response" = "y" ]]
    then
        sed -i '/vnc/d' /etc/pve/local/qemu-server/$vm.conf
        echo Enter the VNC display# to use\(\2 digits\)\:
        read display
        echo "args: -vnc 0.0.0.0:$display" >> /etc/pve/local/qemu-server/$vm.conf
        echo
        echo "You can access your VM remotely at <Proxmox IP>:59$display"
        echo
        echo "======================================================="
    else
        echo "Goodbye"
        echo
    fi

else
echo "No VNC Port found!"
echo
echo Enter the VNC display# to use\(\2 digits\)\:
read display
echo "args: -vnc 0.0.0.0:$display" >> /etc/pve/local/qemu-server/$vm.conf
echo
echo "You can access your VM remotely at <Proxmox IP>:59$display"
echo
echo "======================================================="

fi