qshutdown: 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/qshutdown - from package: qshutdown

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

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