shinken-scheduler: 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-scheduler - from package: shinken-scheduler

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

On Debian possible default full paths are:

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

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

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