machinectl: command not found

Have You tried accessing the binary with the full path?

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/machinectl - from package: systemd

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