diodon: 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/diodon - from package: diodon

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

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