luci: 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/luci - from package: luci

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

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