filterbuilder: 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/share/doc/libhtmlparser-java-doc/examples/bin/filterbuilder - from package: libhtmlparser-java-doc

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

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