apcsmart: command not found

Have You tried accessing the binary with the full path?

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/apcsmart - from package: nut

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