lockdev: 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/sbin/lockdev - from package: lockdev

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

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