snmpgetnext: 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/snmpgetnext - 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/snmpgetnext - from package: snmp

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

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