rotter: 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/rotter - from package: rotter

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

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