I want to write a simple shell script which would
merge some files into one. Every day I create a new file with the stuff that I learnt or changed on my system. The files' names are eg. 10.03.06, 11.03.06, 12.03.06 etc.
In the same directory I have some other files with names containing letters (not numerals), so I wanted grep to pick
all the files with dates as names and cat to merge them in one file with the name eg. history
when I write:
cat | grep [^a-zA-Z] > history
it creates the file history, but it's empty. I mean,
know it can't work but I can't think of anything else

Ideally, later on the script would append only files
from the last week to the history file and would be
run as a weekly cron job.
thanks

Grep searches the contents of files for patterns, not the filenames themselves, unless you are using it in a pipe to filter the output of "ls" or "find".
You could simply use globbing.

cat [[:digit:]][[:digit:]].03.06 >history

If you want to add to the end of the history file, then use ">>" instead of ">".

thanks jschiwal, that's exactly what I meant