quiterss: command not found

Have You tried accessing the binary with the full path?

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/quiterss - from package: quiterss

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