mpdkilljob: 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/mpdkilljob - from package: mpich2

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

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