wash: 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:

/usr/bin/wash - from package: reaver

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

On Debian possible default full paths are:

/usr/bin/wash - from package: reaver

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

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