diracparser: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH

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/diracparser - from package: mkvtoolnix

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