prerex: 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/prerex - from package: prerex

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

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