fnid: 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/fnid - from package: id-utils

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

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