stumpish: 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/stumpish - from package: stumpwm

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

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