cube4to3: command not found

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

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

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 CentOS possible default full paths are:

/usr/bin/cube4to3 - from package: cube

You may install the required package with command yum install {package}

Error in other languages:
cube4to3: bevel nie gevind nie
cube4to3: comandă negăsită
cube4to3: comando não encontrado
cube4to3: commande introuvable
cube4to3: command not found
cube4to3: käsku ei ole
cube4to3: không tìm thấy lệnh
cube4to3: komanda nerasta
cube4to3: Kommando nicht gefunden.
cube4to3: kommandot finns inte
cube4to3: komut yok
cube4to3: nie znaleziono polecenia
cube4to3: níor aimsíodh an t-ordú
cube4to3: no se encontró la orden
cube4to3: no s'ha trobat l'ordre
cube4to3: opdracht niet gevonden
cube4to3: parancs nem található
cube4to3: perintah tidak ditemukan
cube4to3: príkaz nenájdený
cube4to3: příkaz nenalezen
cube4to3: команда не найдена
cube4to3: командата не е открита
cube4to3: 命令找不到
cube4to3: コマンドが見つかりません