memlockd: 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 Debian possible default full paths are:

/usr/sbin/memlockd - from package: memlockd

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

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