During logroate, if there comes a log entry, where will this log entry goes? To the rotated file, lost, or to the newly created file?
It depends.
The logrotate process
In RHEL 6 (centos 6), logrotate works like below:
1. Rename the original file. For example, /var/log/messages --> /var/log/messages.1
2. Create a new file. In this example, create an empty /var/log/messages
3. Run post-rotate script. For rsyslog, it would send a HUP signal to rsyslogd.