blackbox: 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
/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 Debian possible default full paths are:

/usr/bin/blackbox - from package: blackbox

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