ratfor: 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/ratfor - from package: ratfor

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

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