tripplite: 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 - from package: nut

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

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