update-service: 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/sbin/update-service - from package: daemontools-run
/usr/sbin/update-service - from package: runit

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

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