I used an alias to generate a log file for an application to produce the log file with time of invoking like this

alias app org_app -log `date| cut -c 5-7,9-10,12-13,15-16,18-19`.log

and I entered in the .cshrc file.
but the date is stored when I invoke the .cshrc file.
so, if in a same session, I invoke the application several times, i get my log file overwritten.

Is there a solution for this?

If you place the alias assignment in single quotes, then the expression will get stored as is. Without the quotes, it will store the evaluation of the expression, which would be good for locking in an evaluated expression to remain static for duration of the session. In the following, the date command will return the same value as your "date|cut".

alias app 'org_app -log `date +%b%d%H%M%S`.log'

To see what is getting stored for the alias, type:
alias app

thanks Jimbo,
that's just what I wanted.
It's wonderful