snmpkey: 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
/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/snmpkey - from package: perl-Net-SNMP

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

On Debian possible default full paths are:

/usr/bin/snmpkey - from package: libnet-snmp-perl

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