autopep8: 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/autopep8 - from package: python-autopep8

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

Error in other languages:
autopep8: bevel nie gevind nie
autopep8: comandă negăsită
autopep8: comando não encontrado
autopep8: commande introuvable
autopep8: command not found
autopep8: käsku ei ole
autopep8: không tìm thấy lệnh
autopep8: komanda nerasta
autopep8: Kommando nicht gefunden.
autopep8: kommandot finns inte
autopep8: komut yok
autopep8: nie znaleziono polecenia
autopep8: níor aimsíodh an t-ordú
autopep8: no se encontró la orden
autopep8: no s'ha trobat l'ordre
autopep8: opdracht niet gevonden
autopep8: parancs nem található
autopep8: perintah tidak ditemukan
autopep8: príkaz nenájdený
autopep8: příkaz nenalezen
autopep8: команда не найдена
autopep8: командата не е открита
autopep8: 命令找不到
autopep8: コマンドが見つかりません