vnc4config: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/vnc4config - from package: vnc4server

You may install the required package with command apt-get install {package}
Error in other languages:
vnc4config: bevel nie gevind nie
vnc4config: comandă negăsită
vnc4config: comando não encontrado
vnc4config: commande introuvable
vnc4config: command not found
vnc4config: käsku ei ole
vnc4config: không tìm thấy lệnh
vnc4config: komanda nerasta
vnc4config: Kommando nicht gefunden.
vnc4config: kommandot finns inte
vnc4config: komut yok
vnc4config: nie znaleziono polecenia
vnc4config: níor aimsíodh an t-ordú
vnc4config: no se encontró la orden
vnc4config: no s'ha trobat l'ordre
vnc4config: opdracht niet gevonden
vnc4config: parancs nem található
vnc4config: perintah tidak ditemukan
vnc4config: príkaz nenájdený
vnc4config: příkaz nenalezen
vnc4config: команда не найдена
vnc4config: командата не е открита
vnc4config: 命令找不到
vnc4config: コマンドが見つかりません