filename: 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/filename - from package: wcstools

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

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