iasl: 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/iasl - from package: iasl

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

On Debian possible default full paths are:

/usr/bin/iasl - from package: acpica-tools

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

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