dwfilter: 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/dwfilter - from package: dwdiff

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

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