hi,

I need some for shell.
How can modify a file to get
the same lines appended
the same line with some pattern modified
(exemple below)

Thanks for your ...

before:
aaaazzzzaaaa
bbbbzzzzbbbb
cccczzzzcccc
ddddzzzzdddd


after:
aaaazzzzaaaa aaaayyyyaaaa
bbbbzzzzbbbb bbbbyyyybbbb
cccczzzzcccc ccccyyyycccc
ddddzzzzdddd ddddyyyydddd