cube3to4: 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/cube3to4 - from package: cube

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

Error in other languages:
cube3to4: bevel nie gevind nie
cube3to4: comandă negăsită
cube3to4: comando não encontrado
cube3to4: commande introuvable
cube3to4: command not found
cube3to4: käsku ei ole
cube3to4: không tìm thấy lệnh
cube3to4: komanda nerasta
cube3to4: Kommando nicht gefunden.
cube3to4: kommandot finns inte
cube3to4: komut yok
cube3to4: nie znaleziono polecenia
cube3to4: níor aimsíodh an t-ordú
cube3to4: no se encontró la orden
cube3to4: no s'ha trobat l'ordre
cube3to4: opdracht niet gevonden
cube3to4: parancs nem található
cube3to4: perintah tidak ditemukan
cube3to4: príkaz nenájdený
cube3to4: příkaz nenalezen
cube3to4: команда не найдена
cube3to4: командата не е открита
cube3to4: 命令找不到
cube3to4: コマンドが見つかりません