nr: 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/nr - from package: netrw

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

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