easy_install3: 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/easy_install3 - from package: python3-setuptools

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

Error in other languages:
easy_install3: bevel nie gevind nie
easy_install3: comandă negăsită
easy_install3: comando não encontrado
easy_install3: commande introuvable
easy_install3: command not found
easy_install3: käsku ei ole
easy_install3: không tìm thấy lệnh
easy_install3: komanda nerasta
easy_install3: Kommando nicht gefunden.
easy_install3: kommandot finns inte
easy_install3: komut yok
easy_install3: nie znaleziono polecenia
easy_install3: níor aimsíodh an t-ordú
easy_install3: no se encontró la orden
easy_install3: no s'ha trobat l'ordre
easy_install3: opdracht niet gevonden
easy_install3: parancs nem található
easy_install3: perintah tidak ditemukan
easy_install3: príkaz nenájdený
easy_install3: příkaz nenalezen
easy_install3: команда не найдена
easy_install3: командата не е открита
easy_install3: 命令找不到
easy_install3: コマンドが見つかりません