mib2c-update: 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 CentOS possible default full paths are:

/usr/bin/mib2c-update - from package: net-snmp-perl

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

On Debian possible default full paths are:

/usr/bin/mib2c-update - from package: libsnmp-dev

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

Error in other languages:
mib2c-update: bevel nie gevind nie
mib2c-update: comandă negăsită
mib2c-update: comando não encontrado
mib2c-update: commande introuvable
mib2c-update: command not found
mib2c-update: käsku ei ole
mib2c-update: không tìm thấy lệnh
mib2c-update: komanda nerasta
mib2c-update: Kommando nicht gefunden.
mib2c-update: kommandot finns inte
mib2c-update: komut yok
mib2c-update: nie znaleziono polecenia
mib2c-update: níor aimsíodh an t-ordú
mib2c-update: no se encontró la orden
mib2c-update: no s'ha trobat l'ordre
mib2c-update: opdracht niet gevonden
mib2c-update: parancs nem található
mib2c-update: perintah tidak ditemukan
mib2c-update: príkaz nenájdený
mib2c-update: příkaz nenalezen
mib2c-update: команда не найдена
mib2c-update: командата не е открита
mib2c-update: 命令找不到
mib2c-update: コマンドが見つかりません