ifplugstatus: 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/sbin/ifplugstatus - from package: ifplugd

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

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