fai-make-nfsroot: 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/sbin/fai-make-nfsroot - from package: fai-server

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