wifi-status: 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/wifi-status - from package: byobu

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

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