qmc-gui: 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
/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/qmc-gui - from package: qmc

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