dwww-refresh-cache: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH

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-refresh-cache - from package: dwww

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