seccure-dh: 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/seccure-dh - from package: seccure

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

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