apol: 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/apol - from package: setools-gui

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

On Debian possible default full paths are:

/usr/bin/apol - from package: setools-gui

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

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