silentjack: 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 Debian possible default full paths are:

/usr/bin/silentjack - from package: silentjack

You may install the required package with command apt-get install {package}

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