dwww-convert: 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/sbin/dwww-convert - from package: dwww

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

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