udhcpd: 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/udhcpd - from package: udhcpd

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