htmlclean: 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/htmlclean - from package: libhtml-clean-perl

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

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