kmplayer: 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/kmplayer - from package: kmplayer

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

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