silent: 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/silent - from package: emboss

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

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