qtractor: 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/qtractor - from package: qtractor

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

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