njb-getusage: 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/njb-getusage - from package: libnjb-tools

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

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