sisu-webrick: 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/sisu-webrick - from package: sisu

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

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