bf_copy-bdb: 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/bf_copy-bdb - from package: bogofilter-bdb

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

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