upsrw: 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/bin/upsrw - from package: nut-client

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

On Debian possible default full paths are:

/bin/upsrw - from package: nut-client

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

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