bestups: 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/bestups - from package: nut

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

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