update-python-modules: 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/sbin/update-python-modules - from package: python-support

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

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