mpdtrace: 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/mpdtrace - from package: mpich2

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

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