cube_diff: 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/cube_diff - from package: cube

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

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