prank: 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/prank - from package: prank

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

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