systemd: 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:

/bin/systemd - from package: systemd

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

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