dbf-rb: 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/dbf-rb - from package: ruby-dbf

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

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