build-pysnmp-mib: 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

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 CentOS possible default full paths are:

/usr/bin/build-pysnmp-mib - from package: pysnmp

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/build-pysnmp-mib - from package: python-pysnmp4

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