apcaccess: 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/apcaccess - from package: apcupsd

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

On Debian possible default full paths are:

/sbin/apcaccess - from package: apcupsd

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

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