n-m: 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/n-m - from package: python-networkmanager

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

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