memping: 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/memping - from package: libmemcached10

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

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