update-passwd: 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/update-passwd - from package: base-passwd

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

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