wmshutdown: 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/wmshutdown - from package: wmshutdown

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

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