update-mime: 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-mime - from package: mime-support

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

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