acpiexec: 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 Debian possible default full paths are:

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

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

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