service_started: 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:

/lib/rc/bin/service_started - from package: openrc

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

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