memhog: 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/memhog - from package: numactl

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

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