i want to find unix file created how many days ago?
This will display files in the current directory modified 10 days ago.
find ./ -mtime 10
Afaik there is no create time in Unix/Linux.
There is only
ctime
atime
mtime
which are explained here:
i want to ( systemdate - file_last_update_date ) for specific file...
try this 
# stat infle