qtqr: 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/qtqr - from package: qtqr

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

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