shinken-discovery: 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/sbin/shinken-discovery - from package: shinken

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

On Debian possible default full paths are:

/usr/bin/shinken-discovery - from package: shinken-common

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

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