njplot: 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/njplot - from package: njplot

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

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