update-metainit: 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-metainit - from package: metainit

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

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