kshutdown: 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/kshutdown - from package: kshutdown

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

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