fence_ipmilan: 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/fence_ipmilan - from package: fence-agents

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

On Debian possible default full paths are:

/usr/sbin/fence_ipmilan - from package: fence-agents

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

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