Small problem

hello, i am a newbie and i really need your help

i have an centos 6.5 and i wonder if i can create a list with random 4 letters :


if it can be done , i will really apreciate your help ! THANKS !!!

---------- Post updated at 07:16 AM ---------- Previous update was at 07:13 AM ----------

ohhh...i forgot ....

i want to use all letters....all posibilities.....

Moderator's Comments:

edit by bakunin: when posting file content, terminal output or code always use CODE-tags please. Thank you.