wmacpi-cli: 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/wmacpi-cli - from package: wmacpi

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

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