jack_freewheel: 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 CentOS possible default full paths are:

/usr/bin/jack_freewheel - from package: jack-audio-connection-kit

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/jack_freewheel - from package: jackd1
/usr/bin/jack_freewheel - from package: jackd2

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

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