wihack: 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/wihack - from package: wmii

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

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