Pls need advice on forging custom diclists

[heretolearn]

What is the easiest way to do such operations :
1-pick all 8 chars long words from a list file and create a new one with them only.
2- append a couple predefined pre or suffix to these words (123, 111, 007 for example)

I would rather do this in a linux terminal but i dont mind using a windows gui app.

Thank you, any help is greatly appreciated.