iw: 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 CentOS possible default full paths are:

/sbin/iw - from package: iw

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/sbin/iw - from package: iw

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

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