ardour2: 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/ardour2 - from package: ardour

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

Error in other languages:
ardour2: bevel nie gevind nie
ardour2: comandă negăsită
ardour2: comando não encontrado
ardour2: commande introuvable
ardour2: command not found
ardour2: käsku ei ole
ardour2: không tìm thấy lệnh
ardour2: komanda nerasta
ardour2: Kommando nicht gefunden.
ardour2: kommandot finns inte
ardour2: komut yok
ardour2: nie znaleziono polecenia
ardour2: níor aimsíodh an t-ordú
ardour2: no se encontró la orden
ardour2: no s'ha trobat l'ordre
ardour2: opdracht niet gevonden
ardour2: parancs nem található
ardour2: perintah tidak ditemukan
ardour2: príkaz nenájdený
ardour2: příkaz nenalezen
ardour2: команда не найдена
ardour2: командата не е открита
ardour2: 命令找不到
ardour2: コマンドが見つかりません