snmpd: 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/sbin/snmpd - from package: net-snmp

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

On Debian possible default full paths are:

/usr/sbin/snmpd - from package: snmpd

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

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