snmptrap: 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/snmptrap - from package: net-snmp-utils

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

On Debian possible default full paths are:

/usr/bin/snmptrap - from package: snmp

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

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