net-snmp-create-v3-user: 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/net-snmp-create-v3-user - from package: net-snmp

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

On Debian possible default full paths are:

/usr/bin/net-snmp-create-v3-user - from package: libsnmp-dev

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

Error in other languages:
net-snmp-create-v3-user: bevel nie gevind nie
net-snmp-create-v3-user: comandă negăsită
net-snmp-create-v3-user: comando não encontrado
net-snmp-create-v3-user: commande introuvable
net-snmp-create-v3-user: command not found
net-snmp-create-v3-user: käsku ei ole
net-snmp-create-v3-user: không tìm thấy lệnh
net-snmp-create-v3-user: komanda nerasta
net-snmp-create-v3-user: Kommando nicht gefunden.
net-snmp-create-v3-user: kommandot finns inte
net-snmp-create-v3-user: komut yok
net-snmp-create-v3-user: nie znaleziono polecenia
net-snmp-create-v3-user: níor aimsíodh an t-ordú
net-snmp-create-v3-user: no se encontró la orden
net-snmp-create-v3-user: no s'ha trobat l'ordre
net-snmp-create-v3-user: opdracht niet gevonden
net-snmp-create-v3-user: parancs nem található
net-snmp-create-v3-user: perintah tidak ditemukan
net-snmp-create-v3-user: príkaz nenájdený
net-snmp-create-v3-user: příkaz nenalezen
net-snmp-create-v3-user: команда не найдена
net-snmp-create-v3-user: командата не е открита
net-snmp-create-v3-user: 命令找不到
net-snmp-create-v3-user: コマンドが見つかりません