ftwhich: 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/ftwhich - from package: whichman

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

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