systemd-delta: 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/systemd-delta - from package: systemd

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

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