Findex: 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/Findex - from package: ferret-vis

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

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