lurker-prune: 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/lurker-prune - from package: lurker

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

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