nose2-3: 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/nose2-3 - from package: python3-nose2

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

Error in other languages:
nose2-3: bevel nie gevind nie
nose2-3: comandă negăsită
nose2-3: comando não encontrado
nose2-3: commande introuvable
nose2-3: command not found
nose2-3: käsku ei ole
nose2-3: không tìm thấy lệnh
nose2-3: komanda nerasta
nose2-3: Kommando nicht gefunden.
nose2-3: kommandot finns inte
nose2-3: komut yok
nose2-3: nie znaleziono polecenia
nose2-3: níor aimsíodh an t-ordú
nose2-3: no se encontró la orden
nose2-3: no s'ha trobat l'ordre
nose2-3: opdracht niet gevonden
nose2-3: parancs nem található
nose2-3: perintah tidak ditemukan
nose2-3: príkaz nenájdený
nose2-3: příkaz nenalezen
nose2-3: команда не найдена
nose2-3: командата не е открита
nose2-3: 命令找不到
nose2-3: コマンドが見つかりません