pysnmpwalk: 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/pysnmpwalk - from package: python-pysnmp4-apps

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

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