memdump: 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/memdump - from package: libmemcached10
/usr/bin/memdump - from package: libmemcached

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

On Debian possible default full paths are:

/usr/sbin/memdump - from package: memdump

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

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