mpginfo: 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/bin/mpginfo - from package: mpgtx

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

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