mlocate: 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/bin/mlocate - from package: mlocate

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

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