dragon: 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/dragon - from package: kdemultimedia

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

On Debian possible default full paths are:

/usr/bin/dragon - from package: dragonplayer

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

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