py-asterisk: command not found

Have You tried accessing the binary with the full path?

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/py-asterisk - from package: python-asterisk

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