rebuild-pysnmp-mibs: 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/rebuild-pysnmp-mibs - from package: python-pysnmp4-mibs

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

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