filext: 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/filext - from package: wcstools

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

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