fai-chboot: 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/sbin/fai-chboot - from package: fai-server

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

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