dwb: 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/dwb - from package: dwb

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

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