prefix: 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/prefix - from package: libapp-options-perl

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

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