tripplite_usb: 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:

/sbin/tripplite_usb - from package: nut

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

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