mkdhparams: 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/sbin/mkdhparams - from package: courier-ssl

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

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