mwfilter: 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/mwfilter - from package: emboss

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

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