kmix: 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/kmix - from package: kdemultimedia

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

On Debian possible default full paths are:

/usr/bin/kmix - from package: kmix

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

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