n_files: command not found

Have You tried accessing the binary with the full path?

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/lib/fastdnaml/bin/n_files - from package: fastdnaml

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