falrun: 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/falrun - from package: falconpl

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

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