s5: 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/s5 - from package: s5

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

Error in other languages:
s5: bevel nie gevind nie
s5: comandă negăsită
s5: comando não encontrado
s5: commande introuvable
s5: command not found
s5: käsku ei ole
s5: không tìm thấy lệnh
s5: komanda nerasta
s5: Kommando nicht gefunden.
s5: kommandot finns inte
s5: komut yok
s5: nie znaleziono polecenia
s5: níor aimsíodh an t-ordú
s5: no se encontró la orden
s5: no s'ha trobat l'ordre
s5: opdracht niet gevonden
s5: parancs nem található
s5: perintah tidak ditemukan
s5: príkaz nenájdený
s5: příkaz nenalezen
s5: команда не найдена
s5: командата не е открита
s5: 命令找不到
s5: コマンドが見つかりません