dh_systemd_start: 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/dh_systemd_start - from package: dh-systemd

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

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