gmp3info: 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/gmp3info - from package: mp3info-gtk

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

Error in other languages:
gmp3info: bevel nie gevind nie
gmp3info: comandă negăsită
gmp3info: comando não encontrado
gmp3info: commande introuvable
gmp3info: command not found
gmp3info: käsku ei ole
gmp3info: không tìm thấy lệnh
gmp3info: komanda nerasta
gmp3info: Kommando nicht gefunden.
gmp3info: kommandot finns inte
gmp3info: komut yok
gmp3info: nie znaleziono polecenia
gmp3info: níor aimsíodh an t-ordú
gmp3info: no se encontró la orden
gmp3info: no s'ha trobat l'ordre
gmp3info: opdracht niet gevonden
gmp3info: parancs nem található
gmp3info: perintah tidak ditemukan
gmp3info: príkaz nenájdený
gmp3info: příkaz nenalezen
gmp3info: команда не найдена
gmp3info: командата не е открита
gmp3info: 命令找不到
gmp3info: コマンドが見つかりません