systemd-cat: 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-cat - from package: systemd

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

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